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Ebru Akagunduz 7269586252 mm, thp: make swapin readahead under down_read of mmap_sem 
Currently khugepaged makes swapin readahead under down_write.  This
patch supplies to make swapin readahead under down_read instead of
down_write.

The patch was tested with a test program that allocates 800MB of memory,
writes to it, and then sleeps.  The system was forced to swap out all.
Afterwards, the test program touches the area by writing, it skips a
page in each 20 pages of the area.

[akpm@linux-foundation.org: update comment to match new code]
[kirill.shutemov@linux.intel.com: passing 'vma' to hugepage_vma_revlidate() is useless]
  Link: http://lkml.kernel.org/r/20160530095058.GA53044@black.fi.intel.com
  Link: http://lkml.kernel.org/r/1466021202-61880-3-git-send-email-kirill.shutemov@linux.intel.com
Link: http://lkml.kernel.org/r/1464335964-6510-4-git-send-email-ebru.akagunduz@gmail.com
Link: http://lkml.kernel.org/r/1466021202-61880-2-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-07-26 16:19:19 -07:00
Ebru Akagunduz 8a966ed746 mm: make swapin readahead to improve thp collapse rate 
This patch makes swapin readahead to improve thp collapse rate.  When
khugepaged scanned pages, there can be a few of the pages in swap area.

With the patch THP can collapse 4kB pages into a THP when there are up
to max_ptes_swap swap ptes in a 2MB range.

The patch was tested with a test program that allocates 400B of memory,
writes to it, and then sleeps.  I force the system to swap out all.
Afterwards, the test program touches the area by writing, it skips a
page in each 20 pages of the area.

Without the patch, system did not swap in readahead.  THP rate was %65
of the program of the memory, it did not change over time.

With this patch, after 10 minutes of waiting khugepaged had collapsed
%99 of the program's memory.

[kirill.shutemov@linux.intel.com: trivial cleanup of exit path of the function]
[kirill.shutemov@linux.intel.com: __collapse_huge_page_swapin(): drop unused 'pte' parameter]
[kirill.shutemov@linux.intel.com: do not hold anon_vma lock during swap in]
Signed-off-by: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Xie XiuQi <xiexiuqi@huawei.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: David Rientjes <rientjes@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-07-26 16:19:19 -07:00
Ebru Akagunduz 70652f6ec0 mm: make optimistic check for swapin readahead 
Introduce a new sysfs integer knob
/sys/kernel/mm/transparent_hugepage/khugepaged/max_ptes_swap which makes
optimistic check for swapin readahead to increase thp collapse rate.
Before getting swapped out pages to memory, checks them and allows up to a
certain number.  It also prints out using tracepoints amount of unmapped
ptes.

[vdavydov@parallels.com: fix scan not aborted on SCAN_EXCEED_SWAP_PTE]
[sfr@canb.auug.org.au: build fix]
  Link: http://lkml.kernel.org/r/20160616154503.65806e12@canb.auug.org.au
Signed-off-by: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Xie XiuQi <xiexiuqi@huawei.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: David Rientjes <rientjes@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-07-26 16:19:19 -07:00
Aneesh Kumar K.V e77b0852b5 mm/mmu_gather: track page size with mmu gather and force flush if page size change 
This allows an arch which needs to do special handing with respect to
different page size when flushing tlb to implement the same in mmu
gather.

Link: http://lkml.kernel.org/r/1465049193-22197-3-git-send-email-aneesh.kumar@linux.vnet.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-07-26 16:19:19 -07:00
Naoya Horiguchi 33f4751e99 mm: thp: move pmd check inside ptl for freeze_page() 
I found a race condition triggering VM_BUG_ON() in freeze_page(), when
running a testcase with 3 processes:
  - process 1: keep writing thp,
  - process 2: keep clearing soft-dirty bits from virtual address of process 1
  - process 3: call migratepages for process 1,

The kernel message is like this:

  kernel BUG at /src/linux-dev/mm/huge_memory.c:3096!
  invalid opcode: 0000 [#1] SMP
  Modules linked in: cfg80211 rfkill crc32c_intel ppdev serio_raw pcspkr virtio_balloon virtio_console parport_pc parport pvpanic acpi_cpufreq tpm_tis tpm i2c_piix4 virtio_blk virtio_net ata_generic pata_acpi floppy virtio_pci virtio_ring virtio
  CPU: 0 PID: 28863 Comm: migratepages Not tainted 4.6.0-v4.6-160602-0827-+ #2
  Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
  task: ffff880037320000 ti: ffff88007cdd0000 task.ti: ffff88007cdd0000
  RIP: 0010:[<ffffffff811f8e06>]  [<ffffffff811f8e06>] split_huge_page_to_list+0x496/0x590
  RSP: 0018:ffff88007cdd3b70  EFLAGS: 00010202
  RAX: 0000000000000001 RBX: ffff88007c7b88c0 RCX: 0000000000000000
  RDX: 0000000000000000 RSI: 0000000700000200 RDI: ffffea0003188000
  RBP: ffff88007cdd3bb8 R08: 0000000000000001 R09: 00003ffffffff000
  R10: ffff880000000000 R11: ffffc000001fffff R12: ffffea0003188000
  R13: ffffea0003188000 R14: 0000000000000000 R15: 0400000000000080
  FS:  00007f8ec241d740(0000) GS:ffff88007dc00000(0000) knlGS:0000000000000000             CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007f8ec1f3ed20 CR3: 000000003707b000 CR4: 00000000000006f0
  Call Trace:
    ? list_del+0xd/0x30
    queue_pages_pte_range+0x4d1/0x590
    __walk_page_range+0x204/0x4e0
    walk_page_range+0x71/0xf0
    queue_pages_range+0x75/0x90
    ? queue_pages_hugetlb+0x190/0x190
    ? new_node_page+0xc0/0xc0
    ? change_prot_numa+0x40/0x40
    migrate_to_node+0x71/0xd0
    do_migrate_pages+0x1c3/0x210
    SyS_migrate_pages+0x261/0x290
    entry_SYSCALL_64_fastpath+0x1a/0xa4
  Code: e8 b0 87 fb ff 0f 0b 48 c7 c6 30 32 9f 81 e8 a2 87 fb ff 0f 0b 48 c7 c6 b8 46 9f 81 e8 94 87 fb ff 0f 0b 85 c0 0f 84 3e fd ff ff <0f> 0b 85 c0 0f 85 a6 00 00 00 48 8b 75 c0 4c 89 f7 41 be f0 ff
  RIP   split_huge_page_to_list+0x496/0x590

I'm not sure of the full scenario of the reproduction, but my debug
showed that split_huge_pmd_address(freeze=true) returned without running
main code of pmd splitting because pmd_present(*pmd) in precheck somehow
returned 0.  If this happens, the subsequent try_to_unmap() fails and
returns non-zero (because page_mapcount() still > 0), and finally
VM_BUG_ON() fires.  This patch tries to fix it by prechecking pmd state
inside ptl.

Link: http://lkml.kernel.org/r/1466990929-7452-1-git-send-email-n-horiguchi@ah.jp.nec.com
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-07-15 14:54:27 +09:00
Huang Ying 9818b8cde6 madvise_free, thp: fix madvise_free_huge_pmd return value after splitting 
madvise_free_huge_pmd should return 0 if the fallback PTE operations are
required.  In madvise_free_huge_pmd, if part pages of THP are discarded,
the THP will be split and fallback PTE operations should be used if
splitting succeeds.  But the original code will make fallback PTE
operations skipped, after splitting succeeds.  Fix that via make
madvise_free_huge_pmd return 0 after splitting successfully, so that the
fallback PTE operations will be done.

Link: http://lkml.kernel.org/r/1467135452-16688-1-git-send-email-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-07-15 14:54:27 +09:00
Linus Torvalds 1f40c49570 libnvdimm for 4.7 
1/ Device DAX for persistent memory:
    Device DAX is the device-centric analogue of Filesystem DAX
    (CONFIG_FS_DAX).  It allows memory ranges to be allocated and mapped
    without need of an intervening file system.  Device DAX is strict,
    precise and predictable.  Specifically this interface:
 
    a) Guarantees fault granularity with respect to a given page size
       (pte, pmd, or pud) set at configuration time.
 
    b) Enforces deterministic behavior by being strict about what fault
       scenarios are supported.
 
    Persistent memory is the first target, but the mechanism is also
    targeted for exclusive allocations of performance/feature differentiated
    memory ranges.
 
 2/ Support for the HPE DSM (device specific method) command formats.
    This enables management of these first generation devices until a
    unified DSM specification materializes.
 
 3/ Further ACPI 6.1 compliance with support for the common dimm
    identifier format.
 
 4/ Various fixes and cleanups across the subsystem.
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Merge tag 'libnvdimm-for-4.7' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

Pull libnvdimm updates from Dan Williams:
 "The bulk of this update was stabilized before the merge window and
  appeared in -next.  The "device dax" implementation was revised this
  week in response to review feedback, and to address failures detected
  by the recently expanded ndctl unit test suite.

  Not included in this pull request are two dax topic branches (dax
  error handling, and dax radix-tree locking).  These topics were
  deferred to get a few more days of -next integration testing, and to
  coordinate a branch baseline with Ted and the ext4 tree.  Vishal and
  Ross will send the error handling and locking topics respectively in
  the next few days.

  This branch has received a positive build result from the kbuild robot
  across 226 configs.

  Summary:

   - Device DAX for persistent memory: Device DAX is the device-centric
     analogue of Filesystem DAX (CONFIG_FS_DAX).  It allows memory
     ranges to be allocated and mapped without need of an intervening
     file system.  Device DAX is strict, precise and predictable.
     Specifically this interface:

      a) Guarantees fault granularity with respect to a given page size
         (pte, pmd, or pud) set at configuration time.

      b) Enforces deterministic behavior by being strict about what
         fault scenarios are supported.

     Persistent memory is the first target, but the mechanism is also
     targeted for exclusive allocations of performance/feature
     differentiated memory ranges.

   - Support for the HPE DSM (device specific method) command formats.
     This enables management of these first generation devices until a
     unified DSM specification materializes.

   - Further ACPI 6.1 compliance with support for the common dimm
     identifier format.

   - Various fixes and cleanups across the subsystem"

* tag 'libnvdimm-for-4.7' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm: (40 commits)
  libnvdimm, dax: fix deletion
  libnvdimm, dax: fix alignment validation
  libnvdimm, dax: autodetect support
  libnvdimm: release ida resources
  Revert "block: enable dax for raw block devices"
  /dev/dax, core: file operations and dax-mmap
  /dev/dax, pmem: direct access to persistent memory
  libnvdimm: stop requiring a driver ->remove() method
  libnvdimm, dax: record the specified alignment of a dax-device instance
  libnvdimm, dax: reserve space to store labels for device-dax
  libnvdimm, dax: introduce device-dax infrastructure
  nfit: add sysfs dimm 'family' and 'dsm_mask' attributes
  tools/testing/nvdimm: ND_CMD_CALL support
  nfit: disable vendor specific commands
  nfit: export subsystem ids as attributes
  nfit: fix format interface code byte order per ACPI6.1
  nfit, libnvdimm: limited/whitelisted dimm command marshaling mechanism
  nfit, libnvdimm: clarify "commands" vs "_DSMs"
  libnvdimm: increase max envelope size for ioctl
  acpi/nfit: Add sysfs "id" for NVDIMM ID
  ...
 2016-05-23 11:18:01 -07:00
Dan Williams dee4107924 /dev/dax, core: file operations and dax-mmap 
The "Device DAX" core enables dax mappings of performance / feature
differentiated memory.  An open mapping or file handle keeps the backing
struct device live, but new mappings are only possible while the device
is enabled.   Faults are handled under rcu_read_lock to synchronize
with the enabled state of the device.

Similar to the filesystem-dax case the backing memory may optionally
have struct page entries.  However, unlike fs-dax there is no support
for private mappings, or mappings that are not backed by media (see
use of zero-page in fs-dax).

Mappings are always guaranteed to match the alignment of the dax_region.
If the dax_region is configured to have a 2MB alignment, all mappings
are guaranteed to be backed by a pmd entry.  Contrast this determinism
with the fs-dax case where pmd mappings are opportunistic.  If userspace
attempts to force a misaligned mapping, the driver will fail the mmap
attempt.  See dax_dev_check_vma() for other scenarios that are rejected,
like MAP_PRIVATE mappings.

Cc: Hannes Reinecke <hare@suse.de>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
 2016-05-20 22:02:55 -07:00
David Rientjes f050897778 mm, thp: khugepaged should scan when sleep value is written 
If a large value is written to scan_sleep_millisecs, for example, that
period must lapse before khugepaged will wake up for periodic
collapsing.

If this value is tuned to 1 day, for example, and then re-tuned to its
default 10s, khugepaged will still wait for a day before scanning again.

This patch causes khugepaged to wakeup immediately when the value is
changed and then sleep until that value is rewritten or the new value
lapses.

Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1605181453200.4786@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-05-20 17:58:30 -07:00
Andrea Arcangeli d5ee7c3bcc mm: thp: split_huge_pmd_address() comment improvement 
Comment is partly wrong, this improves it by including the case of
split_huge_pmd_address() called by try_to_unmap_one if TTU_SPLIT_HUGE_PMD
is set.

Link: http://lkml.kernel.org/r/1462547040-1737-4-git-send-email-aarcange@redhat.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-05-20 17:58:30 -07:00
Yang Shi 340a43bed6 mm: thp: simplify the implementation of mk_huge_pmd() 
The implementation of mk_huge_pmd looks verbose, it could be just
simplified to one line code.

Signed-off-by: Yang Shi <yang.shi@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-05-20 17:58:30 -07:00
Hugh Dickins bf8616d5fa huge mm: move_huge_pmd does not need new_vma 
Remove move_huge_pmd()'s redundant new_vma arg: all it was used for was
a VM_NOHUGEPAGE check on new_vma flags, but the new_vma is cloned from
the old vma, so a trans_huge_pmd in the new_vma will be as acceptable as
it was in the old vma, alignment and size permitting.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Yang Shi <yang.shi@linaro.org>
Cc: Ning Qu <quning@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-05-19 19:12:14 -07:00
Joonsoo Kim 0139aa7b7f mm: rename _count, field of the struct page, to _refcount 
Many developers already know that field for reference count of the
struct page is _count and atomic type.  They would try to handle it
directly and this could break the purpose of page reference count
tracepoint.  To prevent direct _count modification, this patch rename it
to _refcount and add warning message on the code.  After that, developer
who need to handle reference count will find that field should not be
accessed directly.

[akpm@linux-foundation.org: fix comments, per Vlastimil]
[akpm@linux-foundation.org: Documentation/vm/transhuge.txt too]
[sfr@canb.auug.org.au: sync ethernet driver changes]
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Sunil Goutham <sgoutham@cavium.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Manish Chopra <manish.chopra@qlogic.com>
Cc: Yuval Mintz <yuval.mintz@qlogic.com>
Cc: Tariq Toukan <tariqt@mellanox.com>
Cc: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-05-19 19:12:14 -07:00
Andrea Arcangeli 6d0a07edd1 mm: thp: calculate the mapcount correctly for THP pages during WP faults 
This will provide fully accuracy to the mapcount calculation in the
write protect faults, so page pinning will not get broken by false
positive copy-on-writes.

total_mapcount() isn't the right calculation needed in
reuse_swap_page(), so this introduces a page_trans_huge_mapcount()
that is effectively the full accurate return value for page_mapcount()
if dealing with Transparent Hugepages, however we only use the
page_trans_huge_mapcount() during COW faults where it strictly needed,
due to its higher runtime cost.

This also provide at practical zero cost the total_mapcount
information which is needed to know if we can still relocate the page
anon_vma to the local vma. If page_trans_huge_mapcount() returns 1 we
can reuse the page no matter if it's a pte or a pmd_trans_huge
triggering the fault, but we can only relocate the page anon_vma to
the local vma->anon_vma if we're sure it's only this "vma" mapping the
whole THP physical range.

Kirill A. Shutemov discovered the problem with moving the page
anon_vma to the local vma->anon_vma in a previous version of this
patch and another problem in the way page_move_anon_rmap() was called.

Andrew Morton discovered that CONFIG_SWAP=n wouldn't build in a
previous version, because reuse_swap_page must be a macro to call
page_trans_huge_mapcount from swap.h, so this uses a macro again
instead of an inline function. With this change at least it's a less
dangerous usage than it was before, because "page" is used only once
now, while with the previous code reuse_swap_page(page++) would have
called page_mapcount on page+1 and it would have increased page twice
instead of just once.

Dean Luick noticed an uninitialized variable that could result in a
rmap inefficiency for the non-THP case in a previous version.

Mike Marciniszyn said:

: Our RDMA tests are seeing an issue with memory locking that bisects to
: commit 61f5d698cc ("mm: re-enable THP")
:
: The test program registers two rather large MRs (512M) and RDMA
: writes data to a passive peer using the first and RDMA reads it back
: into the second MR and compares that data.  The sizes are chosen randomly
: between 0 and 1024 bytes.
:
: The test will get through a few (<= 4 iterations) and then gets a
: compare error.
:
: Tracing indicates the kernel logical addresses associated with the individual
: pages at registration ARE correct , the data in the "RDMA read response only"
: packets ARE correct.
:
: The "corruption" occurs when the packet crosse two pages that are not physically
: contiguous.   The second page reads back as zero in the program.
:
: It looks like the user VA at the point of the compare error no longer points to
: the same physical address as was registered.
:
: This patch totally resolves the issue!

Link: http://lkml.kernel.org/r/1462547040-1737-2-git-send-email-aarcange@redhat.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: "Kirill A. Shutemov" <kirill@shutemov.name>
Reviewed-by: Dean Luick <dean.luick@intel.com>
Tested-by: Alex Williamson <alex.williamson@redhat.com>
Tested-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Tested-by: Josh Collier <josh.d.collier@intel.com>
Cc: Marc Haber <mh+linux-kernel@zugschlus.de>
Cc: <stable@vger.kernel.org>	[4.5]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-05-12 15:52:50 -07:00
Yang Shi 145bdaa150 mm: thp: correct split_huge_pages file permission 
split_huge_pages doesn't support get method at all, so the read
permission sounds confusing, change the permission to write only.

And, add "\n" to the output of set method to make it more readable.

Signed-off-by: Yang Shi <yang.shi@linaro.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-05-05 17:38:53 -07:00
Konstantin Khlebnikov 3486b85a29 mm/huge_memory: replace VM_NO_THP VM_BUG_ON with actual VMA check 
Khugepaged detects own VMAs by checking vm_file and vm_ops but this way
it cannot distinguish private /dev/zero mappings from other special
mappings like /dev/hpet which has no vm_ops and popultes PTEs in mmap.

This fixes false-positive VM_BUG_ON and prevents installing THP where
they are not expected.

Link: http://lkml.kernel.org/r/CACT4Y+ZmuZMV5CjSFOeXviwQdABAgT7T+StKfTqan9YDtgEi5g@mail.gmail.com
Fixes: 78f11a2557 ("mm: thp: fix /dev/zero MAP_PRIVATE and vm_flags cleanups")
Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-04-28 19:34:04 -07:00
Kirill A. Shutemov aa88b68c3b thp: keep huge zero page pinned until tlb flush 
Andrea has found[1] a race condition on MMU-gather based TLB flush vs
split_huge_page() or shrinker which frees huge zero under us (patch 1/2
and 2/2 respectively).

With new THP refcounting, we don't need patch 1/2: mmu_gather keeps the
page pinned until flush is complete and the pin prevents the page from
being split under us.

We still need patch 2/2.  This is simplified version of Andrea's patch.
We don't need fancy encoding.

[1] http://lkml.kernel.org/r/1447938052-22165-1-git-send-email-aarcange@redhat.com

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-04-28 19:34:04 -07:00
Kirill A. Shutemov 0fda2788b0 thp: fix typo in khugepaged_scan_pmd() 
!PageLRU should lead to SCAN_PAGE_LRU, not SCAN_SCAN_ABORT result.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-03-25 16:37:42 -07:00
Linus Torvalds d5e2d00898 powerpc updates for 4.6 
Highlights:
  - Restructure Linux PTE on Book3S/64 to Radix format from Paul Mackerras
  - Book3s 64 MMU cleanup in preparation for Radix MMU from Aneesh Kumar K.V
  - Add POWER9 cputable entry from Michael Neuling
  - FPU/Altivec/VSX save/restore optimisations from Cyril Bur
  - Add support for new ftrace ABI on ppc64le from Torsten Duwe
 
 Various cleanups & minor fixes from:
  - Adam Buchbinder, Andrew Donnellan, Balbir Singh, Christophe Leroy, Cyril
    Bur, Luis Henriques, Madhavan Srinivasan, Pan Xinhui, Russell Currey,
    Sukadev Bhattiprolu, Suraj Jitindar Singh.
 
 General:
  - atomics: Allow architectures to define their own __atomic_op_* helpers from
    Boqun Feng
  - Implement atomic{, 64}_*_return_* variants and acquire/release/relaxed
    variants for (cmp)xchg from Boqun Feng
  - Add powernv_defconfig from Jeremy Kerr
  - Fix BUG_ON() reporting in real mode from Balbir Singh
  - Add xmon command to dump OPAL msglog from Andrew Donnellan
  - Add xmon command to dump process/task similar to ps(1) from Douglas Miller
  - Clean up memory hotplug failure paths from David Gibson
 
 pci/eeh:
  - Redesign SR-IOV on PowerNV to give absolute isolation between VFs from Wei
    Yang.
  - EEH Support for SRIOV VFs from Wei Yang and Gavin Shan.
  - PCI/IOV: Rename and export virtfn_{add, remove} from Wei Yang
  - PCI: Add pcibios_bus_add_device() weak function from Wei Yang
  - MAINTAINERS: Update EEH details and maintainership from Russell Currey
 
 cxl:
  - Support added to the CXL driver for running on both bare-metal and
    hypervisor systems, from Christophe Lombard and Frederic Barrat.
  - Ignore probes for virtual afu pci devices from Vaibhav Jain
 
 perf:
  - Export Power8 generic and cache events to sysfs from Sukadev Bhattiprolu
  - hv-24x7: Fix usage with chip events, display change in counter values,
    display domain indices in sysfs, eliminate domain suffix in event names,
    from Sukadev Bhattiprolu
 
 Freescale:
  - Updates from Scott: "Highlights include 8xx optimizations, 32-bit checksum
    optimizations, 86xx consolidation, e5500/e6500 cpu hotplug, more fman and
    other dt bits, and minor fixes/cleanup."
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Merge tag 'powerpc-4.6-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc updates from Michael Ellerman:
 "This was delayed a day or two by some build-breakage on old toolchains
  which we've now fixed.

  There's two PCI commits both acked by Bjorn.

  There's one commit to mm/hugepage.c which is (co)authored by Kirill.

  Highlights:
   - Restructure Linux PTE on Book3S/64 to Radix format from Paul
     Mackerras
   - Book3s 64 MMU cleanup in preparation for Radix MMU from Aneesh
     Kumar K.V
   - Add POWER9 cputable entry from Michael Neuling
   - FPU/Altivec/VSX save/restore optimisations from Cyril Bur
   - Add support for new ftrace ABI on ppc64le from Torsten Duwe

  Various cleanups & minor fixes from:
   - Adam Buchbinder, Andrew Donnellan, Balbir Singh, Christophe Leroy,
     Cyril Bur, Luis Henriques, Madhavan Srinivasan, Pan Xinhui, Russell
     Currey, Sukadev Bhattiprolu, Suraj Jitindar Singh.

  General:
   - atomics: Allow architectures to define their own __atomic_op_*
     helpers from Boqun Feng
   - Implement atomic{, 64}_*_return_* variants and acquire/release/
     relaxed variants for (cmp)xchg from Boqun Feng
   - Add powernv_defconfig from Jeremy Kerr
   - Fix BUG_ON() reporting in real mode from Balbir Singh
   - Add xmon command to dump OPAL msglog from Andrew Donnellan
   - Add xmon command to dump process/task similar to ps(1) from Douglas
     Miller
   - Clean up memory hotplug failure paths from David Gibson

  pci/eeh:
   - Redesign SR-IOV on PowerNV to give absolute isolation between VFs
     from Wei Yang.
   - EEH Support for SRIOV VFs from Wei Yang and Gavin Shan.
   - PCI/IOV: Rename and export virtfn_{add, remove} from Wei Yang
   - PCI: Add pcibios_bus_add_device() weak function from Wei Yang
   - MAINTAINERS: Update EEH details and maintainership from Russell
     Currey

  cxl:
   - Support added to the CXL driver for running on both bare-metal and
     hypervisor systems, from Christophe Lombard and Frederic Barrat.
   - Ignore probes for virtual afu pci devices from Vaibhav Jain

  perf:
   - Export Power8 generic and cache events to sysfs from Sukadev
     Bhattiprolu
   - hv-24x7: Fix usage with chip events, display change in counter
     values, display domain indices in sysfs, eliminate domain suffix in
     event names, from Sukadev Bhattiprolu

  Freescale:
   - Updates from Scott: "Highlights include 8xx optimizations, 32-bit
     checksum optimizations, 86xx consolidation, e5500/e6500 cpu
     hotplug, more fman and other dt bits, and minor fixes/cleanup"

* tag 'powerpc-4.6-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (179 commits)
  powerpc: Fix unrecoverable SLB miss during restore_math()
  powerpc/8xx: Fix do_mtspr_cpu6() build on older compilers
  powerpc/rcpm: Fix build break when SMP=n
  powerpc/book3e-64: Use hardcoded mttmr opcode
  powerpc/fsl/dts: Add "jedec,spi-nor" flash compatible
  powerpc/T104xRDB: add tdm riser card node to device tree
  powerpc32: PAGE_EXEC required for inittext
  powerpc/mpc85xx: Add pcsphy nodes to FManV3 device tree
  powerpc/mpc85xx: Add MDIO bus muxing support to the board device tree(s)
  powerpc/86xx: Introduce and use common dtsi
  powerpc/86xx: Update device tree
  powerpc/86xx: Move dts files to fsl directory
  powerpc/86xx: Switch to kconfig fragments approach
  powerpc/86xx: Update defconfigs
  powerpc/86xx: Consolidate common platform code
  powerpc32: Remove one insn in mulhdu
  powerpc32: small optimisation in flush_icache_range()
  powerpc: Simplify test in __dma_sync()
  powerpc32: move xxxxx_dcache_range() functions inline
  powerpc32: Remove clear_pages() and define clear_page() inline
  ...
 2016-03-19 15:38:41 -07:00
Kirill A. Shutemov 5f7377147c thp: fix deadlock in split_huge_pmd() 
split_huge_pmd() tries to munlock page with munlock_vma_page().  That
requires the page to locked.

If the is locked by caller, we would get a deadlock:

	Unable to find swap-space signature
	INFO: task trinity-c85:1907 blocked for more than 120 seconds.
	      Not tainted 4.4.0-00032-gf19d0bdced41-dirty #1606
	"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
	trinity-c85     D ffff88084d997608     0  1907    309 0x00000000
	Call Trace:
	  schedule+0x9f/0x1c0
	  schedule_timeout+0x48e/0x600
	  io_schedule_timeout+0x1c3/0x390
	  bit_wait_io+0x29/0xd0
	  __wait_on_bit_lock+0x94/0x140
	  __lock_page+0x1d4/0x280
	  __split_huge_pmd+0x5a8/0x10f0
	  split_huge_pmd_address+0x1d9/0x230
	  try_to_unmap_one+0x540/0xc70
	  rmap_walk_anon+0x284/0x810
	  rmap_walk_locked+0x11e/0x190
	  try_to_unmap+0x1b1/0x4b0
	  split_huge_page_to_list+0x49d/0x18a0
	  follow_page_mask+0xa36/0xea0
	  SyS_move_pages+0xaf3/0x1570
	  entry_SYSCALL_64_fastpath+0x12/0x6b
	2 locks held by trinity-c85/1907:
	 #0:  (&mm->mmap_sem){++++++}, at:  SyS_move_pages+0x933/0x1570
	 #1:  (&anon_vma->rwsem){++++..}, at:  split_huge_page_to_list+0x402/0x18a0

I don't think the deadlock is triggerable without split_huge_page()
simplifilcation patchset.

But munlock_vma_page() here is wrong: we want to munlock the page
unconditionally, no need in rmap lookup, that munlock_vma_page() does.

Let's use clear_page_mlock() instead.  It can be called under ptl.

Fixes: e90309c9f7 ("thp: allow mlocked THP again")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-03-17 15:09:34 -07:00
Kirill A. Shutemov fec89c109f thp: rewrite freeze_page()/unfreeze_page() with generic rmap walkers 
freeze_page() and unfreeze_page() helpers evolved in rather complex
beasts.  It would be nice to cut complexity of this code.

This patch rewrites freeze_page() using standard try_to_unmap().
unfreeze_page() is rewritten with remove_migration_ptes().

The result is much simpler.

But the new variant is somewhat slower for PTE-mapped THPs.  Current
helpers iterates over VMAs the compound page is mapped to, and then over
ptes within this VMA.  New helpers iterates over small page, then over
VMA the small page mapped to, and only then find relevant pte.

We have short cut for PMD-mapped THP: we directly install migration
entries on PMD split.

I don't think the slowdown is critical, considering how much simpler
result is and that split_huge_page() is quite rare nowadays.  It only
happens due memory pressure or migration.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-03-17 15:09:34 -07:00
Kirill A. Shutemov 2a52bcbcc6 rmap: extend try_to_unmap() to be usable by split_huge_page() 
Add support for two ttu_flags:

  - TTU_SPLIT_HUGE_PMD would split PMD if it's there, before trying to
    unmap page;

  - TTU_RMAP_LOCKED indicates that caller holds relevant rmap lock;

Also, change rwc->done to !page_mapcount() instead of !page_mapped().
try_to_unmap() works on pte level, so we are really interested in the
mappedness of this small page rather than of the compound page it's a
part of.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-03-17 15:09:34 -07:00
Joe Perches 756a025f00 mm: coalesce split strings 
Kernel style prefers a single string over split strings when the string is
'user-visible'.

Miscellanea:

 - Add a missing newline
 - Realign arguments

Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Tejun Heo <tj@kernel.org>	[percpu]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-03-17 15:09:34 -07:00
Joonsoo Kim fe896d1878 mm: introduce page reference manipulation functions 
The success of CMA allocation largely depends on the success of
migration and key factor of it is page reference count.  Until now, page
reference is manipulated by direct calling atomic functions so we cannot
follow up who and where manipulate it.  Then, it is hard to find actual
reason of CMA allocation failure.  CMA allocation should be guaranteed
to succeed so finding offending place is really important.

In this patch, call sites where page reference is manipulated are
converted to introduced wrapper function.  This is preparation step to
add tracepoint to each page reference manipulation function.  With this
facility, we can easily find reason of CMA allocation failure.  There is
no functional change in this patch.

In addition, this patch also converts reference read sites.  It will
help a second step that renames page._count to something else and
prevents later attempt to direct access to it (Suggested by Andrew).

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-03-17 15:09:34 -07:00
Mel Gorman 444eb2a449 mm: thp: set THP defrag by default to madvise and add a stall-free defrag option 
THP defrag is enabled by default to direct reclaim/compact but not wake
kswapd in the event of a THP allocation failure.  The problem is that
THP allocation requests potentially enter reclaim/compaction.  This
potentially incurs a severe stall that is not guaranteed to be offset by
reduced TLB misses.  While there has been considerable effort to reduce
the impact of reclaim/compaction, it is still a high cost and workloads
that should fit in memory fail to do so.  Specifically, a simple
anon/file streaming workload will enter direct reclaim on NUMA at least
even though the working set size is 80% of RAM.  It's been years and
it's time to throw in the towel.

First, this patch defines THP defrag as follows;

 madvise: A failed allocation will direct reclaim/compact if the application requests it
 never:   Neither reclaim/compact nor wake kswapd
 defer:   A failed allocation will wake kswapd/kcompactd
 always:  A failed allocation will direct reclaim/compact (historical behaviour)
          khugepaged defrag will enter direct/reclaim but not wake kswapd.

Next it sets the default defrag option to be "madvise" to only enter
direct reclaim/compaction for applications that specifically requested
it.

Lastly, it removes a check from the page allocator slowpath that is
related to __GFP_THISNODE to allow "defer" to work.  The callers that
really cares are slub/slab and they are updated accordingly.  The slab
one may be surprising because it also corrects a comment as kswapd was
never woken up by that path.

This means that a THP fault will no longer stall for most applications
by default and the ideal for most users that get THP if they are
immediately available.  There are still options for users that prefer a
stall at startup of a new application by either restoring historical
behaviour with "always" or pick a half-way point with "defer" where
kswapd does some of the work in the background and wakes kcompactd if
necessary.  THP defrag for khugepaged remains enabled and will enter
direct/reclaim but no wakeup kswapd or kcompactd.

After this patch a THP allocation failure will quickly fallback and rely
on khugepaged to recover the situation at some time in the future.  In
some cases, this will reduce THP usage but the benefit of THP is hard to
measure and not a universal win where as a stall to reclaim/compaction
is definitely measurable and can be painful.

The first test for this is using "usemem" to read a large file and write
a large anonymous mapping (to avoid the zero page) multiple times.  The
total size of the mappings is 80% of RAM and the benchmark simply
measures how long it takes to complete.  It uses multiple threads to see
if that is a factor.  On UMA, the performance is almost identical so is
not reported but on NUMA, we see this

usemem
                                   4.4.0                 4.4.0
                          kcompactd-v1r1         nodefrag-v1r3
Amean    System-1       102.86 (  0.00%)       46.81 ( 54.50%)
Amean    System-4        37.85 (  0.00%)       34.02 ( 10.12%)
Amean    System-7        48.12 (  0.00%)       46.89 (  2.56%)
Amean    System-12       51.98 (  0.00%)       56.96 ( -9.57%)
Amean    System-21       80.16 (  0.00%)       79.05 (  1.39%)
Amean    System-30      110.71 (  0.00%)      107.17 (  3.20%)
Amean    System-48      127.98 (  0.00%)      124.83 (  2.46%)
Amean    Elapsd-1       185.84 (  0.00%)      105.51 ( 43.23%)
Amean    Elapsd-4        26.19 (  0.00%)       25.58 (  2.33%)
Amean    Elapsd-7        21.65 (  0.00%)       21.62 (  0.16%)
Amean    Elapsd-12       18.58 (  0.00%)       17.94 (  3.43%)
Amean    Elapsd-21       17.53 (  0.00%)       16.60 (  5.33%)
Amean    Elapsd-30       17.45 (  0.00%)       17.13 (  1.84%)
Amean    Elapsd-48       15.40 (  0.00%)       15.27 (  0.82%)

For a single thread, the benchmark completes 43.23% faster with this
patch applied with smaller benefits as the thread increases.  Similar,
notice the large reduction in most cases in system CPU usage.  The
overall CPU time is

               4.4.0       4.4.0
        kcompactd-v1r1 nodefrag-v1r3
User        10357.65    10438.33
System       3988.88     3543.94
Elapsed      2203.01     1634.41

Which is substantial. Now, the reclaim figures

                                 4.4.0       4.4.0
                          kcompactd-v1r1nodefrag-v1r3
Minor Faults                 128458477   278352931
Major Faults                   2174976         225
Swap Ins                      16904701           0
Swap Outs                     17359627           0
Allocation stalls                43611           0
DMA allocs                           0           0
DMA32 allocs                  19832646    19448017
Normal allocs                614488453   580941839
Movable allocs                       0           0
Direct pages scanned          24163800           0
Kswapd pages scanned                 0           0
Kswapd pages reclaimed               0           0
Direct pages reclaimed        20691346           0
Compaction stalls                42263           0
Compaction success                 938           0
Compaction failures              41325           0

This patch eliminates almost all swapping and direct reclaim activity.
There is still overhead but it's from NUMA balancing which does not
identify that it's pointless trying to do anything with this workload.

I also tried the thpscale benchmark which forces a corner case where
compaction can be used heavily and measures the latency of whether base
or huge pages were used

thpscale Fault Latencies
                                       4.4.0                 4.4.0
                              kcompactd-v1r1         nodefrag-v1r3
Amean    fault-base-1      5288.84 (  0.00%)     2817.12 ( 46.73%)
Amean    fault-base-3      6365.53 (  0.00%)     3499.11 ( 45.03%)
Amean    fault-base-5      6526.19 (  0.00%)     4363.06 ( 33.15%)
Amean    fault-base-7      7142.25 (  0.00%)     4858.08 ( 31.98%)
Amean    fault-base-12    13827.64 (  0.00%)    10292.11 ( 25.57%)
Amean    fault-base-18    18235.07 (  0.00%)    13788.84 ( 24.38%)
Amean    fault-base-24    21597.80 (  0.00%)    24388.03 (-12.92%)
Amean    fault-base-30    26754.15 (  0.00%)    19700.55 ( 26.36%)
Amean    fault-base-32    26784.94 (  0.00%)    19513.57 ( 27.15%)
Amean    fault-huge-1      4223.96 (  0.00%)     2178.57 ( 48.42%)
Amean    fault-huge-3      2194.77 (  0.00%)     2149.74 (  2.05%)
Amean    fault-huge-5      2569.60 (  0.00%)     2346.95 (  8.66%)
Amean    fault-huge-7      3612.69 (  0.00%)     2997.70 ( 17.02%)
Amean    fault-huge-12     3301.75 (  0.00%)     6727.02 (-103.74%)
Amean    fault-huge-18     6696.47 (  0.00%)     6685.72 (  0.16%)
Amean    fault-huge-24     8000.72 (  0.00%)     9311.43 (-16.38%)
Amean    fault-huge-30    13305.55 (  0.00%)     9750.45 ( 26.72%)
Amean    fault-huge-32     9981.71 (  0.00%)    10316.06 ( -3.35%)

The average time to fault pages is substantially reduced in the majority
of caseds but with the obvious caveat that fewer THPs are actually used
in this adverse workload

                                   4.4.0                 4.4.0
                          kcompactd-v1r1         nodefrag-v1r3
Percentage huge-1         0.71 (  0.00%)       14.04 (1865.22%)
Percentage huge-3        10.77 (  0.00%)       33.05 (206.85%)
Percentage huge-5        60.39 (  0.00%)       38.51 (-36.23%)
Percentage huge-7        45.97 (  0.00%)       34.57 (-24.79%)
Percentage huge-12       68.12 (  0.00%)       40.07 (-41.17%)
Percentage huge-18       64.93 (  0.00%)       47.82 (-26.35%)
Percentage huge-24       62.69 (  0.00%)       44.23 (-29.44%)
Percentage huge-30       43.49 (  0.00%)       55.38 ( 27.34%)
Percentage huge-32       50.72 (  0.00%)       51.90 (  2.35%)

                                 4.4.0       4.4.0
                          kcompactd-v1r1nodefrag-v1r3
Minor Faults                  37429143    47564000
Major Faults                      1916        1558
Swap Ins                          1466        1079
Swap Outs                      2936863      149626
Allocation stalls                62510           3
DMA allocs                           0           0
DMA32 allocs                   6566458     6401314
Normal allocs                216361697   216538171
Movable allocs                       0           0
Direct pages scanned          25977580       17998
Kswapd pages scanned                 0     3638931
Kswapd pages reclaimed               0      207236
Direct pages reclaimed         8833714          88
Compaction stalls               103349           5
Compaction success                 270           4
Compaction failures             103079           1

Note again that while this does swap as it's an aggressive workload, the
direct relcim activity and allocation stalls is substantially reduced.
There is some kswapd activity but ftrace showed that the kswapd activity
was due to normal wakeups from 4K pages being allocated.
Compaction-related stalls and activity are almost eliminated.

I also tried the stutter benchmark.  For this, I do not have figures for
NUMA but it's something that does impact UMA so I'll report what is
available

stutter
                                 4.4.0                 4.4.0
                        kcompactd-v1r1         nodefrag-v1r3
Min         mmap      7.3571 (  0.00%)      7.3438 (  0.18%)
1st-qrtle   mmap      7.5278 (  0.00%)     17.9200 (-138.05%)
2nd-qrtle   mmap      7.6818 (  0.00%)     21.6055 (-181.25%)
3rd-qrtle   mmap     11.0889 (  0.00%)     21.8881 (-97.39%)
Max-90%     mmap     27.8978 (  0.00%)     22.1632 ( 20.56%)
Max-93%     mmap     28.3202 (  0.00%)     22.3044 ( 21.24%)
Max-95%     mmap     28.5600 (  0.00%)     22.4580 ( 21.37%)
Max-99%     mmap     29.6032 (  0.00%)     25.5216 ( 13.79%)
Max         mmap   4109.7289 (  0.00%)   4813.9832 (-17.14%)
Mean        mmap     12.4474 (  0.00%)     19.3027 (-55.07%)

This benchmark is trying to fault an anonymous mapping while there is a
heavy IO load -- a scenario that desktop users used to complain about
frequently.  This shows a mix because the ideal case of mapping with THP
is not hit as often.  However, note that 99% of the mappings complete
13.79% faster.  The CPU usage here is particularly interesting

               4.4.0       4.4.0
        kcompactd-v1r1nodefrag-v1r3
User           67.50        0.99
System       1327.88       91.30
Elapsed      2079.00     2128.98

And once again we look at the reclaim figures

                                 4.4.0       4.4.0
                          kcompactd-v1r1nodefrag-v1r3
Minor Faults                 335241922  1314582827
Major Faults                       715         819
Swap Ins                             0           0
Swap Outs                            0           0
Allocation stalls               532723           0
DMA allocs                           0           0
DMA32 allocs                1822364341  1177950222
Normal allocs               1815640808  1517844854
Movable allocs                       0           0
Direct pages scanned          21892772           0
Kswapd pages scanned          20015890    41879484
Kswapd pages reclaimed        19961986    41822072
Direct pages reclaimed        21892741           0
Compaction stalls              1065755           0
Compaction success                 514           0
Compaction failures            1065241           0

Allocation stalls and all direct reclaim activity is eliminated as well
as compaction-related stalls.

THP gives impressive gains in some cases but only if they are quickly
available.  We're not going to reach the point where they are completely
free so lets take the costs out of the fast paths finally and defer the
cost to kswapd, kcompactd and khugepaged where it belongs.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-03-17 15:09:34 -07:00
Kirill A. Shutemov f9719a03de thp, vmstats: count deferred split events 
Count how many times we put a THP in split queue.  Currently, it happens
on partial unmap of a THP.

Rapidly growing value can indicate that an application behaves
unfriendly wrt THP: often fault in huge page and then unmap part of it.
This leads to unnecessary memory fragmentation and the application may
require tuning.

The event also can help with debugging kernel [mis-]behaviour.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-03-17 15:09:34 -07:00
Kirill A. Shutemov 8df651c705 thp: cleanup split_huge_page() 
After one of bugfixes to freeze_page(), we don't have freezed pages in
rmap, therefore mapcount of all subpages of freezed THP is zero.  And we
have assert for that.

Let's drop code which deal with non-zero mapcount of subpages.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-03-15 16:55:16 -07:00
Kirill A. Shutemov ff20c2e0ac mm: Some arch may want to use HPAGE_PMD related values as variables 
With next generation power processor, we are having a new mmu model
[1] that require us to maintain a different linux page table format.

Inorder to support both current and future ppc64 systems with a single
kernel we need to make sure kernel can select between different page
table format at runtime. With the new MMU (radix MMU) added, we will
have two different pmd hugepage size 16MB for hash model and 2MB for
Radix model. Hence make HPAGE_PMD related values as a variable.

Actual conversion of HPAGE_PMD to a variable for ppc64 happens in a
followup patch.

[1] http://ibm.biz/power-isa3 (Needs registration).

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
 2016-03-03 21:18:29 +11:00
Michael Ellerman 2527083cb8 powerpc fixes for 4.5 #3 
- eeh: Fix partial hotplug criterion from Gavin Shan
  - mm: Clear the invalid slot information correctly from Aneesh Kumar K.V
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Merge tag 'powerpc-4.5-4' into next

Pull in our current fixes from 4.5, in particular the "Fix Multi hit
ERAT" bug is causing folks some grief when testing next.
 2016-02-25 21:52:58 +11:00
Kirill A. Shutemov 2ac015e293 thp: call pmdp_invalidate() with correct virtual address 
Sebastian Ott and Gerald Schaefer reported random crashes on s390.
It was bisected to my THP refcounting patchset.

The problem is that pmdp_invalidated() called with wrong virtual
address. It got offset up by HPAGE_PMD_SIZE by loop over ptes.

The solution is to introduce new variable to be used in loop and don't
touch 'haddr'.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-and-tested-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Reported-and-tested-by Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-02-24 10:46:30 -08:00
Linus Torvalds e6a1c1e9dd powerpc fixes for 4.5 #2 
- Fix build error on 32-bit with checkpoint restart from Aneesh Kumar
  - Fix dedotify for binutils >= 2.26 from Andreas Schwab
  - Don't trace hcalls on offline CPUs from Denis Kirjanov
  - eeh: Fix stale cached primary bus from Gavin Shan
  - eeh: Fix stale PE primary bus from Gavin Shan
  - mm: Fix Multi hit ERAT cause by recent THP update from Aneesh Kumar K.V
  - ioda: Set "read" permission when "write" is set from Alexey Kardashevskiy
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Merge tag 'powerpc-4.5-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc fixes from Michael Ellerman:
 - Fix build error on 32-bit with checkpoint restart from Aneesh Kumar
 - Fix dedotify for binutils >= 2.26 from Andreas Schwab
 - Don't trace hcalls on offline CPUs from Denis Kirjanov
 - eeh: Fix stale cached primary bus from Gavin Shan
 - eeh: Fix stale PE primary bus from Gavin Shan
 - mm: Fix Multi hit ERAT cause by recent THP update from Aneesh Kumar K.V
 - ioda: Set "read" permission when "write" is set from Alexey Kardashevskiy

* tag 'powerpc-4.5-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/ioda: Set "read" permission when "write" is set
  powerpc/mm: Fix Multi hit ERAT cause by recent THP update
  powerpc/powernv: Fix stale PE primary bus
  powerpc/eeh: Fix stale cached primary bus
  powerpc/pseries: Don't trace hcalls on offline CPUs
  powerpc: Fix dedotify for binutils >= 2.26
  powerpc/book3s_32: Fix build error with checkpoint restart
 2016-02-20 09:22:11 -08:00
Kirill A. Shutemov 69a8ec2d81 thp, dax: do not try to withdraw pgtable from non-anon VMA 
DAX doesn't deposit pgtables when it maps huge pages: nothing to
withdraw. It can lead to crash.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-02-18 16:23:24 -08:00
Aneesh Kumar K.V c777e2a8b6 powerpc/mm: Fix Multi hit ERAT cause by recent THP update 
With ppc64 we use the deposited pgtable_t to store the hash pte slot
information. We should not withdraw the deposited pgtable_t without
marking the pmd none. This ensure that low level hash fault handling
will skip this huge pte and we will handle them at upper levels.

Recent change to pmd splitting changed the above in order to handle the
race between pmd split and exit_mmap. The race is explained below.

Consider following race:

		CPU0				CPU1
shrink_page_list()
  add_to_swap()
    split_huge_page_to_list()
      __split_huge_pmd_locked()
        pmdp_huge_clear_flush_notify()
	// pmd_none() == true
					exit_mmap()
					  unmap_vmas()
					    zap_pmd_range()
					      // no action on pmd since pmd_none() == true
	pmd_populate()

As result the THP will not be freed. The leak is detected by check_mm():

	BUG: Bad rss-counter state mm:ffff880058d2e580 idx:1 val:512

The above required us to not mark pmd none during a pmd split.

The fix for ppc is to clear the huge pte of _PAGE_USER, so that low
level fault handling code skip this pte. At higher level we do take ptl
lock. That should serialze us against the pmd split. Once the lock is
acquired we do check the pmd again using pmd_same. That should always
return false for us and hence we should retry the access. We do the
pmd_same check in all case after taking plt with
THP (do_huge_pmd_wp_page, do_huge_pmd_numa_page and
huge_pmd_set_accessed)

Also make sure we wait for irq disable section in other cpus to finish
before flipping a huge pte entry with a regular pmd entry. Code paths
like find_linux_pte_or_hugepte depend on irq disable to get
a stable pte_t pointer. A parallel thp split need to make sure we
don't convert a pmd pte to a regular pmd entry without waiting for the
irq disable section to finish.

Fixes: eef1b3ba05 ("thp: implement split_huge_pmd()")
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
 2016-02-15 21:10:04 +11:00
Kirill A. Shutemov ae026204a2 thp: make deferred_split_scan() work again 
We need to iterate over split_queue, not local empty list to get
anything split from the shrinker.

Fixes: e3ae19535c ("thp: limit number of object to scan on deferred_split_scan()")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-02-05 18:10:40 -08:00
Matthew Wilcox 12c9d70bd5 mm: fix memory leak in copy_huge_pmd() 
We allocate a pgtable but do not attach it to anything if the PMD is in
a DAX VMA, causing it to leak.

We certainly try to not free pgtables associated with the huge zero page
if the zero page is in a DAX VMA, so I think this is the right solution.
This needs to be properly audited.

Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-02-03 08:28:43 -08:00
Kirill A. Shutemov e3ae19535c thp: limit number of object to scan on deferred_split_scan() 
If we have a lot of pages in queue to be split, deferred_split_scan()
can spend unreasonable amount of time under spinlock with disabled
interrupts.

Let's cap number of pages to split on scan by sc->nr_to_scan.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-02-03 08:28:43 -08:00
Kirill A. Shutemov cb8d68ec16 thp: change deferred_split_count() to return number of THP in queue 
I've got meaning of shrinker::count_objects() wrong: it should return
number of potentially freeable objects, which is not necessary correlate
with freeable memory.

Returning 256 per THP in queue is not reasonable:
shrinker::scan_objects() never called with nr_to_scan > 128 in my setup.

Let's return 1 per THP and correct scan_object accordingly.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-02-03 08:28:43 -08:00
Kirill A. Shutemov a3d0a91850 thp: make split_queue per-node 
Andrea Arcangeli suggested to make split queue per-node to improve
scalability.  Let's do it.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Suggested-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-02-03 08:28:43 -08:00
yalin wang 16fd0fe4aa mm: fix kernel crash in khugepaged thread 
This crash is caused by NULL pointer deference, in page_to_pfn() marco,
when page == NULL :

  Unable to handle kernel NULL pointer dereference at virtual address 00000000
  Internal error: Oops: 94000006 [#1] SMP
  Modules linked in:
  CPU: 1 PID: 26 Comm: khugepaged Tainted: G        W       4.3.0-rc6-next-20151022ajb-00001-g32f3386-dirty #3
  PC is at khugepaged+0x378/0x1af8
  LR is at khugepaged+0x418/0x1af8
  Process khugepaged (pid: 26, stack limit = 0xffffffc079638020)
  Call trace:
    khugepaged+0x378/0x1af8
    kthread+0xdc/0xf4
    ret_from_fork+0xc/0x40
  Code: 35001700 f0002c60 aa0703e3 f9009fa0 (f94000e0)
  ---[ end trace 637503d8e28ae69e  ]---
  Kernel panic - not syncing: Fatal exception
  CPU2: stopping
  CPU: 2 PID: 0 Comm: swapper/2 Tainted: G      D W       4.3.0-rc6-next-20151022ajb-00001-g32f3386-dirty #3
  Hardware name: linux,dummy-virt (DT)

[akpm@linux-foundation.org: fix fat-fingered merge resolution]
Signed-off-by: yalin wang <yalin.wang2010@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-21 17:20:51 -08:00
Kirill A. Shutemov b6ec57f4b9 thp: change pmd_trans_huge_lock() interface to return ptl 
After THP refcounting rework we have only two possible return values
from pmd_trans_huge_lock(): success and failure.  Return-by-pointer for
ptl doesn't make much sense in this case.

Let's convert pmd_trans_huge_lock() to return ptl on success and NULL on
failure.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Minchan Kim <minchan@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-21 17:20:51 -08:00
Kirill A. Shutemov 0b9b6fff7b thp: fix interrupt unsafe locking in split_huge_page() 
split_queue_lock can be taken from interrupt context in some cases, but
I forgot to convert locking in split_huge_page() to interrupt-safe
primitives.

Let's fix this.

lockdep output:

  ======================================================
  [ INFO: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected ]
  4.4.0+ #259 Tainted: G        W
  ------------------------------------------------------
  syz-executor/18183 [HC0[0]:SC0[2]:HE0:SE0] is trying to acquire:
   (split_queue_lock){+.+...}, at: free_transhuge_page+0x24/0x90 mm/huge_memory.c:3436

  and this task is already holding:
   (slock-AF_INET){+.-...}, at: spin_lock_bh include/linux/spinlock.h:307
   (slock-AF_INET){+.-...}, at: lock_sock_fast+0x45/0x120 net/core/sock.c:2462
  which would create a new lock dependency:
   (slock-AF_INET){+.-...} -> (split_queue_lock){+.+...}

  but this new dependency connects a SOFTIRQ-irq-safe lock:
   (slock-AF_INET){+.-...}
  ... which became SOFTIRQ-irq-safe at:
     mark_irqflags kernel/locking/lockdep.c:2799
     __lock_acquire+0xfd8/0x4700 kernel/locking/lockdep.c:3162
     lock_acquire+0x1dc/0x430 kernel/locking/lockdep.c:3585
     __raw_spin_lock include/linux/spinlock_api_smp.h:144
     _raw_spin_lock+0x33/0x50 kernel/locking/spinlock.c:151
     spin_lock include/linux/spinlock.h:302
     udp_queue_rcv_skb+0x781/0x1550 net/ipv4/udp.c:1680
     flush_stack+0x50/0x330 net/ipv6/udp.c:799
     __udp4_lib_mcast_deliver+0x694/0x7f0 net/ipv4/udp.c:1798
     __udp4_lib_rcv+0x17dc/0x23e0 net/ipv4/udp.c:1888
     udp_rcv+0x21/0x30 net/ipv4/udp.c:2108
     ip_local_deliver_finish+0x2b3/0xa50 net/ipv4/ip_input.c:216
     NF_HOOK_THRESH include/linux/netfilter.h:226
     NF_HOOK include/linux/netfilter.h:249
     ip_local_deliver+0x1c4/0x2f0 net/ipv4/ip_input.c:257
     dst_input include/net/dst.h:498
     ip_rcv_finish+0x5ec/0x1730 net/ipv4/ip_input.c:365
     NF_HOOK_THRESH include/linux/netfilter.h:226
     NF_HOOK include/linux/netfilter.h:249
     ip_rcv+0x963/0x1080 net/ipv4/ip_input.c:455
     __netif_receive_skb_core+0x1620/0x2f80 net/core/dev.c:4154
     __netif_receive_skb+0x2a/0x160 net/core/dev.c:4189
     netif_receive_skb_internal+0x1b5/0x390 net/core/dev.c:4217
     napi_skb_finish net/core/dev.c:4542
     napi_gro_receive+0x2bd/0x3c0 net/core/dev.c:4572
     e1000_clean_rx_irq+0x4e2/0x1100 drivers/net/ethernet/intel/e1000e/netdev.c:1038
     e1000_clean+0xa08/0x24a0 drivers/net/ethernet/intel/e1000/e1000_main.c:3819
     napi_poll net/core/dev.c:5074
     net_rx_action+0x7eb/0xdf0 net/core/dev.c:5139
     __do_softirq+0x26a/0x920 kernel/softirq.c:273
     invoke_softirq kernel/softirq.c:350
     irq_exit+0x18f/0x1d0 kernel/softirq.c:391
     exiting_irq ./arch/x86/include/asm/apic.h:659
     do_IRQ+0x86/0x1a0 arch/x86/kernel/irq.c:252
     ret_from_intr+0x0/0x20 arch/x86/entry/entry_64.S:520
     arch_safe_halt ./arch/x86/include/asm/paravirt.h:117
     default_idle+0x52/0x2e0 arch/x86/kernel/process.c:304
     arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:295
     default_idle_call+0x48/0xa0 kernel/sched/idle.c:92
     cpuidle_idle_call kernel/sched/idle.c:156
     cpu_idle_loop kernel/sched/idle.c:252
     cpu_startup_entry+0x554/0x710 kernel/sched/idle.c:300
     rest_init+0x192/0x1a0 init/main.c:412
     start_kernel+0x678/0x69e init/main.c:683
     x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:195
     x86_64_start_kernel+0x158/0x167 arch/x86/kernel/head64.c:184

  to a SOFTIRQ-irq-unsafe lock:
   (split_queue_lock){+.+...}
   which became SOFTIRQ-irq-unsafe at:
     mark_irqflags kernel/locking/lockdep.c:2817
     __lock_acquire+0x146e/0x4700 kernel/locking/lockdep.c:3162
     lock_acquire+0x1dc/0x430 kernel/locking/lockdep.c:3585
     __raw_spin_lock include/linux/spinlock_api_smp.h:144
     _raw_spin_lock+0x33/0x50 kernel/locking/spinlock.c:151
     spin_lock include/linux/spinlock.h:302
     split_huge_page_to_list+0xcc0/0x1c50 mm/huge_memory.c:3399
     split_huge_page include/linux/huge_mm.h:99
     queue_pages_pte_range+0xa38/0xef0 mm/mempolicy.c:507
     walk_pmd_range mm/pagewalk.c:50
     walk_pud_range mm/pagewalk.c:90
     walk_pgd_range mm/pagewalk.c:116
     __walk_page_range+0x653/0xcd0 mm/pagewalk.c:204
     walk_page_range+0xfe/0x2b0 mm/pagewalk.c:281
     queue_pages_range+0xfb/0x130 mm/mempolicy.c:687
     migrate_to_node mm/mempolicy.c:1004
     do_migrate_pages+0x370/0x4e0 mm/mempolicy.c:1109
     SYSC_migrate_pages mm/mempolicy.c:1453
     SyS_migrate_pages+0x640/0x730 mm/mempolicy.c:1374
     entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185

  other info that might help us debug this:

   Possible interrupt unsafe locking scenario:

         CPU0                    CPU1
         ----                    ----
    lock(split_queue_lock);
                                 local_irq_disable();
                                 lock(slock-AF_INET);
                                 lock(split_queue_lock);
    <Interrupt>
      lock(slock-AF_INET);

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-20 17:09:18 -08:00
Arnd Bergmann 629d9d1caf mm: avoid uninitialized variable in tracepoint 
A newly added tracepoint in the hugepage code uses a variable in the
error handling that is not initialized at that point:

include/trace/events/huge_memory.h:81:230: error: 'isolated' may be used uninitialized in this function [-Werror=maybe-uninitialized]

The result is relatively harmless, as the trace data will in rare
cases contain incorrect data.

This works around the problem by adding an explicit initialization.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 7d2eba0557 ("mm: add tracepoint for scanning pages")
Reviewed-by: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-20 09:21:41 -08:00
Linus Torvalds 25eedabe01 vm: fix incorrect unlock error path in madvise_free_huge_pmd 
Commit b8d3c4c300 ("mm/huge_memory.c: don't split THP page when
MADV_FREE syscall is called") introduced this new function, but got the
error handling for when pmd_trans_huge_lock() fails wrong.  In the
failure case, the lock has not been taken, and we should not unlock on
the way out.

Cc: Minchan Kim <minchan@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-17 18:33:15 -08:00
Dan Williams 3565fce3a6 mm, x86: get_user_pages() for dax mappings 
A dax mapping establishes a pte with _PAGE_DEVMAP set when the driver
has established a devm_memremap_pages() mapping, i.e.  when the pfn_t
return from ->direct_access() has PFN_DEV and PFN_MAP set.  Later, when
encountering _PAGE_DEVMAP during a page table walk we lookup and pin a
struct dev_pagemap instance to keep the result of pfn_to_page() valid
until put_page().

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Logan Gunthorpe <logang@deltatee.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Dan Williams 5c7fb56e5e mm, dax: dax-pmd vs thp-pmd vs hugetlbfs-pmd 
A dax-huge-page mapping while it uses some thp helpers is ultimately not
a transparent huge page.  The distinction is especially important in the
get_user_pages() path.  pmd_devmap() is used to distinguish dax-pmds
from pmd_huge() and pmd_trans_huge() which have slightly different
semantics.

Explicitly mark the pmd_trans_huge() helpers that dax needs by adding
pmd_devmap() checks.

[kirill.shutemov@linux.intel.com: fix regression in handling mlocked pages in  __split_huge_pmd()]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Dan Williams f25748e3c3 mm, dax: convert vmf_insert_pfn_pmd() to pfn_t 
Similar to the conversion of vm_insert_mixed() use pfn_t in the
vmf_insert_pfn_pmd() to tag the resulting pte with _PAGE_DEVICE when the
pfn is backed by a devm_memremap_pages() mapping.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Ross Zwisler 01871e59af mm, dax: fix livelock, allow dax pmd mappings to become writeable 
Prior to this change DAX PMD mappings that were made read-only were
never able to be made writable again.  This is because the code in
insert_pfn_pmd() that calls pmd_mkdirty() and pmd_mkwrite() would skip
these calls if the PMD already existed in the page table.

Instead, if we are doing a write always mark the PMD entry as dirty and
writeable.  Without this code we can get into a condition where we mark
the PMD as read-only, and then on a subsequent write fault we get into
an infinite loop of PMD faults where we try unsuccessfully to make the
PMD writeable.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reported-by: Jeff Moyer <jmoyer@redhat.com>
Reported-by: Toshi Kani <toshi.kani@hpe.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Kirill A. Shutemov bd56086f10 thp: fix split_huge_page() after mremap() of THP 
Sasha Levin has reported KASAN out-of-bounds bug[1].  It points to "if
(!is_swap_pte(pte[i]))" in unfreeze_page_vma() as a problematic access.

The cause is that split_huge_page() doesn't handle THP correctly if it's
not allingned to PMD boundary.  It can happen after mremap().

Test-case (not always triggers the bug):

	#define _GNU_SOURCE
	#include <stdio.h>
	#include <stdlib.h>
	#include <sys/mman.h>

	#define MB (1024UL*1024)
	#define SIZE (2*MB)
	#define BASE ((void *)0x400000000000)

	int main()
	{
		char *p;

		p = mmap(BASE, SIZE, PROT_READ | PROT_WRITE,
				MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS | MAP_POPULATE,
				-1, 0);
		if (p == MAP_FAILED)
			perror("mmap"), exit(1);
		p = mremap(BASE, SIZE, SIZE, MREMAP_FIXED | MREMAP_MAYMOVE,
				BASE + SIZE + 8192);
		if (p == MAP_FAILED)
			perror("mremap"), exit(1);
		system("echo 1 > /sys/kernel/debug/split_huge_pages");
		return 0;
	}

The patch fixes freeze and unfreeze paths to handle page table boundary
crossing.

It also makes mapcount vs count check in split_huge_page_to_list()
stricter:
 - after freeze we don't expect any subpage mapped as we remove them
   from rmap when setting up migration entries;
 - count must be 1, meaning only caller has reference to the page;

[1] https://gist.github.com/sashalevin/c67fbea55e7c0576972a

Signed-off-by: Kirill A.  Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Minchan Kim b8d3c4c300 mm/huge_memory.c: don't split THP page when MADV_FREE syscall is called 
We don't need to split THP page when MADV_FREE syscall is called if
[start, len] is aligned with THP size.  The split could be done when VM
decide to free it in reclaim path if memory pressure is heavy.  With
that, we could avoid unnecessary THP split.

For the feature, this patch changes pte dirtness marking logic of THP.
Now, it marks every ptes of pages dirty unconditionally in splitting,
which makes MADV_FREE void.  So, instead, this patch propagates pmd
dirtiness to all pages via PG_dirty and restores pte dirtiness from
PG_dirty.  With this, if pmd is clean(ie, MADV_FREEed) when split
happens(e,g, shrink_page_list), all of pages are clean too so we could
discard them.

Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Shaohua Li <shli@kernel.org>
Cc: <yalin.wang2010@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chen Gang <gang.chen.5i5j@gmail.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Daniel Micay <danielmicay@gmail.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Helge Deller <deller@gmx.de>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Jason Evans <je@fb.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mika Penttil <mika.penttila@nextfour.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Rik van Riel <riel@redhat.com>
Cc: Roland Dreier <roland@kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Shaohua Li <shli@kernel.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Kirill A. Shutemov d965432234 thp: increase split_huge_page() success rate 
During freeze_page(), we remove the page from rmap.  It munlocks the
page if it was mlocked.  clear_page_mlock() uses thelru cache, which
temporary pins the page.

Let's drain the lru cache before checking page's count vs.  mapcount.
The change makes mlocked page split on first attempt, if it was not
pinned by somebody else.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Kirill A. Shutemov 49071d436b thp: add debugfs handle to split all huge pages 
Writing 1 into 'split_huge_pages' will try to find and split all huge
pages in the system.  This is useful for debuging.

[akpm@linux-foundation.org: fix printk text, per Vlastimil]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Kirill A. Shutemov b20ce5e03b mm: prepare page_referenced() and page_idle to new THP refcounting 
Both page_referenced() and page_idle_clear_pte_refs_one() assume that
THP can only be mapped with PMD, so there's no reason to look on PTEs
for PageTransHuge() pages.  That's no true anymore: THP can be mapped
with PTEs too.

The patch removes PageTransHuge() test from the functions and opencode
page table check.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Kirill A. Shutemov e90309c9f7 thp: allow mlocked THP again 
Before THP refcounting rework, THP was not allowed to cross VMA
boundary.  So, if we have THP and we split it, PG_mlocked can be safely
transferred to small pages.

With new THP refcounting and naive approach to mlocking we can end up
with this scenario:
 1. we have a mlocked THP, which belong to one VM_LOCKED VMA.
 2. the process does munlock() on the *part* of the THP:
      - the VMA is split into two, one of them VM_LOCKED;
      - huge PMD split into PTE table;
      - THP is still mlocked;
 3. split_huge_page():
      - it transfers PG_mlocked to *all* small pages regrardless if it
	blong to any VM_LOCKED VMA.

We probably could munlock() all small pages on split_huge_page(), but I
think we have accounting issue already on step two.

Instead of forbidding mlocked pages altogether, we just avoid mlocking
PTE-mapped THPs and munlock THPs on split_huge_pmd().

This means PTE-mapped THPs will be on normal lru lists and will be split
under memory pressure by vmscan.  After the split vmscan will detect
unevictable small pages and mlock them.

With this approach we shouldn't hit situation like described above.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Kirill A. Shutemov 9a982250f7 thp: introduce deferred_split_huge_page() 
Currently we don't split huge page on partial unmap.  It's not an ideal
situation.  It can lead to memory overhead.

Furtunately, we can detect partial unmap on page_remove_rmap().  But we
cannot call split_huge_page() from there due to locking context.

It's also counterproductive to do directly from munmap() codepath: in
many cases we will hit this from exit(2) and splitting the huge page
just to free it up in small pages is not what we really want.

The patch introduce deferred_split_huge_page() which put the huge page
into queue for splitting.  The splitting itself will happen when we get
memory pressure via shrinker interface.  The page will be dropped from
list on freeing through compound page destructor.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Kirill A. Shutemov e9b61f1985 thp: reintroduce split_huge_page() 
This patch adds implementation of split_huge_page() for new
refcountings.

Unlike previous implementation, new split_huge_page() can fail if
somebody holds GUP pin on the page.  It also means that pin on page
would prevent it from bening split under you.  It makes situation in
many places much cleaner.

The basic scheme of split_huge_page():

  - Check that sum of mapcounts of all subpage is equal to page_count()
    plus one (caller pin). Foll off with -EBUSY. This way we can avoid
    useless PMD-splits.

  - Freeze the page counters by splitting all PMD and setup migration
    PTEs.

  - Re-check sum of mapcounts against page_count(). Page's counts are
    stable now. -EBUSY if page is pinned.

  - Split compound page.

  - Unfreeze the page by removing migration entries.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Kirill A. Shutemov ba98828088 thp: add option to setup migration entries during PMD split 
We are going to use migration PTE entries to stabilize page counts.  If
the page is mapped with PMDs we need to split the PMD and setup
migration entries.  It's reasonable to combine these operations to avoid
double-scanning over the page table.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Kirill A. Shutemov eef1b3ba05 thp: implement split_huge_pmd() 
Original split_huge_page() combined two operations: splitting PMDs into
tables of PTEs and splitting underlying compound page.  This patch
implements split_huge_pmd() which split given PMD without splitting
other PMDs this page mapped with or underlying compound page.

Without tail page refcounting, implementation of split_huge_pmd() is
pretty straight-forward.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Kirill A. Shutemov 53f9263bab mm: rework mapcount accounting to enable 4k mapping of THPs 
We're going to allow mapping of individual 4k pages of THP compound.  It
means we need to track mapcount on per small page basis.

Straight-forward approach is to use ->_mapcount in all subpages to track
how many time this subpage is mapped with PMDs or PTEs combined.  But
this is rather expensive: mapping or unmapping of a THP page with PMD
would require HPAGE_PMD_NR atomic operations instead of single we have
now.

The idea is to store separately how many times the page was mapped as
whole -- compound_mapcount.  This frees up ->_mapcount in subpages to
track PTE mapcount.

We use the same approach as with compound page destructor and compound
order to store compound_mapcount: use space in first tail page,
->mapping this time.

Any time we map/unmap whole compound page (THP or hugetlb) -- we
increment/decrement compound_mapcount.  When we map part of compound
page with PTE we operate on ->_mapcount of the subpage.

page_mapcount() counts both: PTE and PMD mappings of the page.

Basically, we have mapcount for a subpage spread over two counters.  It
makes tricky to detect when last mapcount for a page goes away.

We introduced PageDoubleMap() for this.  When we split THP PMD for the
first time and there's other PMD mapping left we offset up ->_mapcount
in all subpages by one and set PG_double_map on the compound page.
These additional references go away with last compound_mapcount.

This approach provides a way to detect when last mapcount goes away on
per small page basis without introducing new overhead for most common
cases.

[akpm@linux-foundation.org: fix typo in comment]
[mhocko@suse.com: ignore partial THP when moving task]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Kirill A. Shutemov 4b471e8898 mm, thp: remove infrastructure for handling splitting PMDs 
With new refcounting we don't need to mark PMDs splitting.  Let's drop
code to handle this.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Kirill A. Shutemov ddc58f27f9 mm: drop tail page refcounting 
Tail page refcounting is utterly complicated and painful to support.

It uses ->_mapcount on tail pages to store how many times this page is
pinned.  get_page() bumps ->_mapcount on tail page in addition to
->_count on head.  This information is required by split_huge_page() to
be able to distribute pins from head of compound page to tails during
the split.

We will need ->_mapcount to account PTE mappings of subpages of the
compound page.  We eliminate need in current meaning of ->_mapcount in
tail pages by forbidding split entirely if the page is pinned.

The only user of tail page refcounting is THP which is marked BROKEN for
now.

Let's drop all this mess.  It makes get_page() and put_page() much
simpler.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Kirill A. Shutemov ad0bed24e9 thp: drop all split_huge_page()-related code 
We will re-introduce new version with new refcounting later in patchset.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Kirill A. Shutemov 122afea962 mm, vmstats: new THP splitting event 
The patch replaces THP_SPLIT with tree events: THP_SPLIT_PAGE,
THP_SPLIT_PAGE_FAILED and THP_SPLIT_PMD.  It reflects the fact that we
are going to be able split PMD without the compound page and that
split_huge_page() can fail.

Signed-off-by: Kirill A.  Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Christoph Lameter <cl@linux.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Kirill A. Shutemov 78ddc53473 thp: rename split_huge_page_pmd() to split_huge_pmd() 
We are going to decouple splitting THP PMD from splitting underlying
compound page.

This patch renames split_huge_page_pmd*() functions to split_huge_pmd*()
to reflect the fact that it doesn't imply page splitting, only PMD.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Kirill A. Shutemov b1caa957ae khugepaged: ignore pmd tables with THP mapped with ptes 
Prepare khugepaged to see compound pages mapped with pte.  For now we
won't collapse the pmd table with such pte.

khugepaged is subject for future rework wrt new refcounting.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Kirill A. Shutemov 7479df6da9 thp, mlock: do not allow huge pages in mlocked area 
With new refcounting THP can belong to several VMAs.  This makes tricky
to track THP pages, when they partially mlocked.  It can lead to leaking
mlocked pages to non-VM_LOCKED vmas and other problems.

With this patch we will split all pages on mlock and avoid
fault-in/collapse new THP in VM_LOCKED vmas.

I've tried alternative approach: do not mark THP pages mlocked and keep
them on normal LRUs.  This way vmscan could try to split huge pages on
memory pressure and free up subpages which doesn't belong to VM_LOCKED
vmas.  But this is user-visible change: we screw up Mlocked accouting
reported in meminfo, so I had to leave this approach aside.

We can bring something better later, but this should be good enough for
now.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Kirill A. Shutemov 1f25fe20a7 mm, thp: adjust conditions when we can reuse the page on WP fault 
With new refcounting we will be able map the same compound page with
PTEs and PMDs.  It requires adjustment to conditions when we can reuse
the page on write-protection fault.

For PTE fault we can't reuse the page if it's part of huge page.

For PMD we can only reuse the page if nobody else maps the huge page or
it's part.  We can do it by checking page_mapcount() on each sub-page,
but it's expensive.

The cheaper way is to check page_count() to be equal 1: every mapcount
takes page reference, so this way we can guarantee, that the PMD is the
only mapping.

This approach can give false negative if somebody pinned the page, but
that doesn't affect correctness.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Kirill A. Shutemov f627c2f537 memcg: adjust to support new THP refcounting 
As with rmap, with new refcounting we cannot rely on PageTransHuge() to
check if we need to charge size of huge page form the cgroup.  We need
to get information from caller to know whether it was mapped with PMD or
PTE.

We do uncharge when last reference on the page gone.  At that point if
we see PageTransHuge() it means we need to unchange whole huge page.

The tricky part is partial unmap -- when we try to unmap part of huge
page.  We don't do a special handing of this situation, meaning we don't
uncharge the part of huge page unless last user is gone or
split_huge_page() is triggered.  In case of cgroup memory pressure
happens the partial unmapped page will be split through shrinker.  This
should be good enough.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Kirill A. Shutemov d281ee6145 rmap: add argument to charge compound page 
We're going to allow mapping of individual 4k pages of THP compound
page.  It means we cannot rely on PageTransHuge() check to decide if
map/unmap small page or THP.

The patch adds new argument to rmap functions to indicate whether we
want to operate on whole compound page or only the small page.

[n-horiguchi@ah.jp.nec.com: fix mapcount mismatch in hugepage migration]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Kirill A. Shutemov 1c290f6421 mm: sanitize page->mapping for tail pages 
We don't define meaning of page->mapping for tail pages.  Currently it's
always NULL, which can be inconsistent with head page and potentially
lead to problems.

Let's poison the pointer to catch all illigal uses.

page_rmapping(), page_mapping() and page_anon_vma() are changed to look
on head page.

The only illegal use I've caught so far is __GPF_COMP pages from sound
subsystem, mapped with PTEs.  do_shared_fault() is changed to use
page_rmapping() instead of direct access to fault_page->mapping.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-15 17:56:32 -08:00
Ebru Akagunduz 7d2eba0557 mm: add tracepoint for scanning pages 
This patch series makes swapin readahead up to a certain number to gain
more thp performance and adds tracepoint for khugepaged_scan_pmd,
collapse_huge_page, __collapse_huge_page_isolate.

This patch series was written to deal with programs that access most,
but not all, of their memory after they get swapped out.  Currently
these programs do not get their memory collapsed into THPs after the
system swapped their memory out, while they would get THPs before
swapping happened.

This patch series was tested with a test program, it allocates 400MB of
memory, writes to it, and then sleeps.  I force the system to swap out
all.  Afterwards, the test program touches the area by writing and
leaves a piece of it without writing.  This shows how much swap in
readahead made by the patch.

Test results:

                        After swapped out
-------------------------------------------------------------------
              | Anonymous | AnonHugePages | Swap      | Fraction  |
-------------------------------------------------------------------
With patch    | 90076 kB    | 88064 kB    | 309928 kB |    %99    |
-------------------------------------------------------------------
Without patch | 194068 kB | 192512 kB     | 205936 kB |    %99    |
-------------------------------------------------------------------

                        After swapped in
-------------------------------------------------------------------
              | Anonymous | AnonHugePages | Swap      | Fraction  |
-------------------------------------------------------------------
With patch    | 201408 kB | 198656 kB     | 198596 kB |    %98    |
-------------------------------------------------------------------
Without patch | 292624 kB | 192512 kB     | 107380 kB |    %65    |
-------------------------------------------------------------------

This patch (of 3):

Using static tracepoints, data of functions is recorded.  It is good to
automatize debugging without doing a lot of changes in the source code.

This patch adds tracepoint for khugepaged_scan_pmd, collapse_huge_page
and __collapse_huge_page_isolate.

[dan.carpenter@oracle.com: add a missing tab]
Signed-off-by: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Xie XiuQi <xiexiuqi@huawei.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2016-01-14 16:00:49 -08:00
Jason J. Herne 1a76361568 mm: loosen MADV_NOHUGEPAGE to enable Qemu postcopy on s390 
MADV_NOHUGEPAGE processing is too restrictive.  kvm already disables
hugepage but hugepage_madvise() takes the error path when we ask to turn
on the MADV_NOHUGEPAGE bit and the bit is already on.  This causes Qemu's
new postcopy migration feature to fail on s390 because its first action is
to madvise the guest address space as NOHUGEPAGE.  This patch modifies the
code so that the operation succeeds without error now.

For consistency reasons do the same for MADV_HUGEPAGE.

Signed-off-by: Jason J. Herne <jjherne@linux.vnet.ibm.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-11-20 16:17:32 -08:00
Linus Torvalds ad804a0b2a Merge branch 'akpm' (patches from Andrew) 
Merge second patch-bomb from Andrew Morton:

 - most of the rest of MM

 - procfs

 - lib/ updates

 - printk updates

 - bitops infrastructure tweaks

 - checkpatch updates

 - nilfs2 update

 - signals

 - various other misc bits: coredump, seqfile, kexec, pidns, zlib, ipc,
   dma-debug, dma-mapping, ...

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (102 commits)
  ipc,msg: drop dst nil validation in copy_msg
  include/linux/zutil.h: fix usage example of zlib_adler32()
  panic: release stale console lock to always get the logbuf printed out
  dma-debug: check nents in dma_sync_sg*
  dma-mapping: tidy up dma_parms default handling
  pidns: fix set/getpriority and ioprio_set/get in PRIO_USER mode
  kexec: use file name as the output message prefix
  fs, seqfile: always allow oom killer
  seq_file: reuse string_escape_str()
  fs/seq_file: use seq_* helpers in seq_hex_dump()
  coredump: change zap_threads() and zap_process() to use for_each_thread()
  coredump: ensure all coredumping tasks have SIGNAL_GROUP_COREDUMP
  signal: remove jffs2_garbage_collect_thread()->allow_signal(SIGCONT)
  signal: introduce kernel_signal_stop() to fix jffs2_garbage_collect_thread()
  signal: turn dequeue_signal_lock() into kernel_dequeue_signal()
  signals: kill block_all_signals() and unblock_all_signals()
  nilfs2: fix gcc uninitialized-variable warnings in powerpc build
  nilfs2: fix gcc unused-but-set-variable warnings
  MAINTAINERS: nilfs2: add header file for tracing
  nilfs2: add tracepoints for analyzing reading and writing metadata files
  ...
 2015-11-07 14:32:45 -08:00
Linus Torvalds 75021d2859 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 
Pull trivial updates from Jiri Kosina:
 "Trivial stuff from trivial tree that can be trivially summed up as:

   - treewide drop of spurious unlikely() before IS_ERR() from Viresh
     Kumar

   - cosmetic fixes (that don't really affect basic functionality of the
     driver) for pktcdvd and bcache, from Julia Lawall and Petr Mladek

   - various comment / printk fixes and updates all over the place"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial:
  bcache: Really show state of work pending bit
  hwmon: applesmc: fix comment typos
  Kconfig: remove comment about scsi_wait_scan module
  class_find_device: fix reference to argument "match"
  debugfs: document that debugfs_remove*() accepts NULL and error values
  net: Drop unlikely before IS_ERR(_OR_NULL)
  mm: Drop unlikely before IS_ERR(_OR_NULL)
  fs: Drop unlikely before IS_ERR(_OR_NULL)
  drivers: net: Drop unlikely before IS_ERR(_OR_NULL)
  drivers: misc: Drop unlikely before IS_ERR(_OR_NULL)
  UBI: Update comments to reflect UBI_METAONLY flag
  pktcdvd: drop null test before destroy functions
 2015-11-07 13:05:44 -08:00
Kirill A. Shutemov 1d798ca3f1 mm: make compound_head() robust 
Hugh has pointed that compound_head() call can be unsafe in some
context. There's one example:

	CPU0					CPU1

isolate_migratepages_block()
  page_count()
    compound_head()
      !!PageTail() == true
					put_page()
					  tail->first_page = NULL
      head = tail->first_page
					alloc_pages(__GFP_COMP)
					   prep_compound_page()
					     tail->first_page = head
					     __SetPageTail(p);
      !!PageTail() == true
    <head == NULL dereferencing>

The race is pure theoretical. I don't it's possible to trigger it in
practice. But who knows.

We can fix the race by changing how encode PageTail() and compound_head()
within struct page to be able to update them in one shot.

The patch introduces page->compound_head into third double word block in
front of compound_dtor and compound_order. Bit 0 encodes PageTail() and
the rest bits are pointer to head page if bit zero is set.

The patch moves page->pmd_huge_pte out of word, just in case if an
architecture defines pgtable_t into something what can have the bit 0
set.

hugetlb_cgroup uses page->lru.next in the second tail page to store
pointer struct hugetlb_cgroup. The patch switch it to use page->private
in the second tail page instead. The space is free since ->first_page is
removed from the union.

The patch also opens possibility to remove HUGETLB_CGROUP_MIN_ORDER
limitation, since there's now space in first tail page to store struct
hugetlb_cgroup pointer. But that's out of scope of the patch.

That means page->compound_head shares storage space with:

 - page->lru.next;
 - page->next;
 - page->rcu_head.next;

That's too long list to be absolutely sure, but looks like nobody uses
bit 0 of the word.

page->rcu_head.next guaranteed[1] to have bit 0 clean as long as we use
call_rcu(), call_rcu_bh(), call_rcu_sched(), or call_srcu(). But future
call_rcu_lazy() is not allowed as it makes use of the bit and we can
get false positive PageTail().

[1] http://lkml.kernel.org/g/20150827163634.GD4029@linux.vnet.ibm.com

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-11-06 17:50:42 -08:00
Aaron Tomlin d6669d689f thp: remove unused vma parameter from khugepaged_alloc_page 
The "vma" parameter to khugepaged_alloc_page() is unused.  It has to
remain unused or the drop read lock 'map_sem' optimisation introduce by
commit 8b1645685a ("mm, THP: don't hold mmap_sem in khugepaged when
allocating THP") wouldn't be safe.  So let's remove it.

Signed-off-by: Aaron Tomlin <atomlin@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-11-06 17:50:42 -08:00
Mel Gorman 974a786e63 mm, page_alloc: remove MIGRATE_RESERVE 
MIGRATE_RESERVE preserves an old property of the buddy allocator that
existed prior to fragmentation avoidance -- min_free_kbytes worth of pages
tended to remain contiguous until the only alternative was to fail the
allocation.  At the time it was discovered that high-order atomic
allocations relied on this property so MIGRATE_RESERVE was introduced.  A
later patch will introduce an alternative MIGRATE_HIGHATOMIC so this patch
deletes MIGRATE_RESERVE and supporting code so it'll be easier to review.
Note that this patch in isolation may look like a false regression if
someone was bisecting high-order atomic allocation failures.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-11-06 17:50:42 -08:00
Mel Gorman 71baba4b92 mm, page_alloc: rename __GFP_WAIT to __GFP_RECLAIM 
__GFP_WAIT was used to signal that the caller was in atomic context and
could not sleep.  Now it is possible to distinguish between true atomic
context and callers that are not willing to sleep.  The latter should
clear __GFP_DIRECT_RECLAIM so kswapd will still wake.  As clearing
__GFP_WAIT behaves differently, there is a risk that people will clear the
wrong flags.  This patch renames __GFP_WAIT to __GFP_RECLAIM to clearly
indicate what it does -- setting it allows all reclaim activity, clearing
them prevents it.

[akpm@linux-foundation.org: fix build]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-11-06 17:50:42 -08:00
Eric B Munson de60f5f10c mm: introduce VM_LOCKONFAULT 
The cost of faulting in all memory to be locked can be very high when
working with large mappings.  If only portions of the mapping will be used
this can incur a high penalty for locking.

For the example of a large file, this is the usage pattern for a large
statical language model (probably applies to other statical or graphical
models as well).  For the security example, any application transacting in
data that cannot be swapped out (credit card data, medical records, etc).

This patch introduces the ability to request that pages are not
pre-faulted, but are placed on the unevictable LRU when they are finally
faulted in.  The VM_LOCKONFAULT flag will be used together with VM_LOCKED
and has no effect when set without VM_LOCKED.  Setting the VM_LOCKONFAULT
flag for a VMA will cause pages faulted into that VMA to be added to the
unevictable LRU when they are faulted or if they are already present, but
will not cause any missing pages to be faulted in.

Exposing this new lock state means that we cannot overload the meaning of
the FOLL_POPULATE flag any longer.  Prior to this patch it was used to
mean that the VMA for a fault was locked.  This means we need the new
FOLL_MLOCK flag to communicate the locked state of a VMA.  FOLL_POPULATE
will now only control if the VMA should be populated and in the case of
VM_LOCKONFAULT, it will not be set.

Signed-off-by: Eric B Munson <emunson@akamai.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-11-05 19:34:48 -08:00
Linus Torvalds 2c2b8285dc - Support for new MM features in ARCv2 cores (THP, PAE40) 
Some generic THP bits are touched - all ACKed by Kirill
 
 - Platform framework updates to prepare for EZChip arrival (still in works)
 
 - ARC Public Mailing list setup finally (linux-snps-arc@lists.infraded.org)
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Merge tag 'arc-4.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc

Pull ARC updates from Vineet Gupta:

 - Support for new MM features in ARCv2 cores (THP, PAE40) Some generic
   THP bits are touched - all ACKed by Kirill

 - Platform framework updates to prepare for EZChip arrival (still in works)

 - ARC Public Mailing list setup finally (linux-snps-arc@lists.infraded.org)

* tag 'arc-4.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc: (42 commits)
  ARC: mm: PAE40 support
  ARC: mm: PAE40: tlbex.S: Explicitify the size of pte_t
  ARC: mm: PAE40: switch to using phys_addr_t for physical addresses
  ARC: mm: HIGHMEM: populate high memory from DT
  ARC: mm: HIGHMEM: kmap API implementation
  ARC: mm: preps ahead of HIGHMEM support #2
  ARC: mm: preps ahead of HIGHMEM support
  ARC: mm: use generic macros _BITUL()/_AC()
  ARC: mm: Improve Duplicate PD Fault handler
  MAINTAINERS: Add public mailing list for ARC
  ARC: Ensure DT mem base is same as what kernel is built with
  ARC: boot: Non Master cpus only need to call EARLY_CPU_SETUP once
  ARCv2: smp: [plat-*]: No need to explicitly call mcip_init_smp()
  ARC: smp: Introduce smp hook @init_irq_cpu called for all cores
  ARC: smp: Rename platform hook @init_smp -> @init_cpu_smp
  ARCv2: smp: [plat-*]: No need to explicitly call mcip_init_early_smp()
  ARC: smp: Introduce smp hook @init_early_smp for Master core
  ARC: remove @init_time, @init_irq platform callbacks
  ARC: smp: irqchip: handle IPI as percpu irq like timer
  ARC: boot: Support Halt-on-reset and Run-on-reset SMP booting modes
  ...
 2015-11-03 13:21:09 -08:00
Minchan Kim 47aee4d8e3 thp: use is_zero_pfn() only after pte_present() check 
Use is_zero_pfn() on pteval only after pte_present() check on pteval
(It might be better idea to introduce is_zero_pte() which checks
pte_present() first).

Otherwise when working on a swap or migration entry and if pte_pfn's
result is equal to zero_pfn by chance, we lose user's data in
__collapse_huge_page_copy().  So if you're unlucky, the application
segfaults and finally you could see below message on exit:

BUG: Bad rss-counter state mm:ffff88007f099300 idx:2 val:3

Fixes: ca0984caa8 ("mm: incorporate zero pages into transparent huge pages")
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: <stable@vger.kernel.org>	[4.1+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-10-23 17:55:10 +09:00
Vineet Gupta 12ebc1581a mm,thp: introduce flush_pmd_tlb_range 
ARCHes with special requirements for evicting THP backing TLB entries
can implement this.

Otherwise also, it can help optimize TLB flush in THP regime.
stock flush_tlb_range() typically has optimization to nuke the entire
TLB if flush span is greater than a certain threshhold, which will
likely be true for a single huge page. Thus a single thp flush will
invalidate the entrire TLB which is not desirable.

e.g. see arch/arc: flush_pmd_tlb_range

Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Link: http://lkml.kernel.org/r/20151009100816.GC7873@node
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
 2015-10-17 17:48:20 +05:30
Viresh Kumar 18e8e5c7a9 mm: Drop unlikely before IS_ERR(_OR_NULL) 
IS_ERR(_OR_NULL) already contain an 'unlikely' compiler flag and there
is no need to do that again from its callers. Drop it.

Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
 2015-09-29 15:15:05 +02:00
Vladimir Davydov 33c3fc71c8 mm: introduce idle page tracking 
Knowing the portion of memory that is not used by a certain application or
memory cgroup (idle memory) can be useful for partitioning the system
efficiently, e.g.  by setting memory cgroup limits appropriately.
Currently, the only means to estimate the amount of idle memory provided
by the kernel is /proc/PID/{clear_refs,smaps}: the user can clear the
access bit for all pages mapped to a particular process by writing 1 to
clear_refs, wait for some time, and then count smaps:Referenced.  However,
this method has two serious shortcomings:

 - it does not count unmapped file pages
 - it affects the reclaimer logic

To overcome these drawbacks, this patch introduces two new page flags,
Idle and Young, and a new sysfs file, /sys/kernel/mm/page_idle/bitmap.
A page's Idle flag can only be set from userspace by setting bit in
/sys/kernel/mm/page_idle/bitmap at the offset corresponding to the page,
and it is cleared whenever the page is accessed either through page tables
(it is cleared in page_referenced() in this case) or using the read(2)
system call (mark_page_accessed()). Thus by setting the Idle flag for
pages of a particular workload, which can be found e.g.  by reading
/proc/PID/pagemap, waiting for some time to let the workload access its
working set, and then reading the bitmap file, one can estimate the amount
of pages that are not used by the workload.

The Young page flag is used to avoid interference with the memory
reclaimer.  A page's Young flag is set whenever the Access bit of a page
table entry pointing to the page is cleared by writing to the bitmap file.
If page_referenced() is called on a Young page, it will add 1 to its
return value, therefore concealing the fact that the Access bit was
cleared.

Note, since there is no room for extra page flags on 32 bit, this feature
uses extended page flags when compiled on 32 bit.

[akpm@linux-foundation.org: fix build]
[akpm@linux-foundation.org: kpageidle requires an MMU]
[akpm@linux-foundation.org: decouple from page-flags rework]
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Reviewed-by: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-09-10 13:29:01 -07:00
Petr Mladek bde43c6c9f mm/khugepaged: allow interruption of allocation sleep again 
Commit 1dfb059b94 ("thp: reduce khugepaged freezing latency") fixed
khugepaged to do not block a system suspend.  But the result is that it
could not get interrupted before the given timeout because the condition
for the wait event is "false".

This patch puts back the original approach but it uses
freezable_schedule_timeout_interruptible() instead of
schedule_timeout_interruptible().  It does the right thing.  I am pretty
sure that the freezable variant was not used in the original fix only
because it was not available at that time.

The regression has been there for ages.  It was not critical.  It just
did the allocation throttling a little bit more aggressively.

I found this problem when converting the kthread to kthread worker API
and trying to understand the code.

This bug is thought to have minimal userspace-visible impact.  Somebody
could set a high alloc_sleep value by mistake, and then try to fix it
back, but khugepaged would keep sleeping until the high value expires.

Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-09-08 15:35:28 -07:00
Vlastimil Babka 96db800f5d mm: rename alloc_pages_exact_node() to __alloc_pages_node() 
alloc_pages_exact_node() was introduced in commit 6484eb3e2a ("page
allocator: do not check NUMA node ID when the caller knows the node is
valid") as an optimized variant of alloc_pages_node(), that doesn't
fallback to current node for nid == NUMA_NO_NODE.  Unfortunately the
name of the function can easily suggest that the allocation is
restricted to the given node and fails otherwise.  In truth, the node is
only preferred, unless __GFP_THISNODE is passed among the gfp flags.

The misleading name has lead to mistakes in the past, see for example
commits 5265047ac3 ("mm, thp: really limit transparent hugepage
allocation to local node") and b360edb43f ("mm, mempolicy:
migrate_to_node should only migrate to node").

Another issue with the name is that there's a family of
alloc_pages_exact*() functions where 'exact' means exact size (instead
of page order), which leads to more confusion.

To prevent further mistakes, this patch effectively renames
alloc_pages_exact_node() to __alloc_pages_node() to better convey that
it's an optimized variant of alloc_pages_node() not intended for general
usage.  Both functions get described in comments.

It has been also considered to really provide a convenience function for
allocations restricted to a node, but the major opinion seems to be that
__GFP_THISNODE already provides that functionality and we shouldn't
duplicate the API needlessly.  The number of users would be small
anyway.

Existing callers of alloc_pages_exact_node() are simply converted to
call __alloc_pages_node(), with the exception of sba_alloc_coherent()
which open-codes the check for NUMA_NO_NODE, so it is converted to use
alloc_pages_node() instead.  This means it no longer performs some
VM_BUG_ON checks, and since the current check for nid in
alloc_pages_node() uses a 'nid < 0' comparison (which includes
NUMA_NO_NODE), it may hide wrong values which would be previously
exposed.

Both differences will be rectified by the next patch.

To sum up, this patch makes no functional changes, except temporarily
hiding potentially buggy callers.  Restricting the checks in
alloc_pages_node() is left for the next patch which can in turn expose
more existing buggy callers.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Robin Holt <robinmholt@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Cliff Whickman <cpw@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-09-08 15:35:28 -07:00
Nicholas Krause 2c0b80d463 mm: make set_recommended_min_free_kbytes() return void 
This makes set_recommended_min_free_kbytes() have a return type of void as
it cannot fail.

Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-09-08 15:35:28 -07:00
Kirill A. Shutemov d295e3415a dax: don't use set_huge_zero_page() 
This is another place where DAX assumed that pgtable_t was a pointer.
Open code the important parts of set_huge_zero_page() in DAX and make
set_huge_zero_page() static again.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-09-08 15:35:28 -07:00
Kirill A. Shutemov da14676900 thp: fix zap_huge_pmd() for DAX 
The original DAX code assumed that pgtable_t was a pointer, which isn't
true on all architectures.  Restructure the code to not rely on that
assumption.

[willy@linux.intel.com: further fixes integrated into this patch]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-09-08 15:35:28 -07:00
Kirill A. Shutemov 5b701b846a thp: decrement refcount on huge zero page if it is split 
The DAX code neglected to put the refcount on the huge zero page.
Also we must notify on splits.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-09-08 15:35:28 -07:00
Matthew Wilcox ae18d6dcf5 thp: change insert_pfn's return type to void 
It would make more sense to have all the return values from
vmf_insert_pfn_pmd() encoded in one place instead of having to follow
the convention into insert_pfn().  Suggested by Jeff Moyer.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-09-08 15:35:28 -07:00
Matthew Wilcox 5cad465d7f mm: add vmf_insert_pfn_pmd() 
Similar to vm_insert_pfn(), but for PMDs rather than PTEs.  The 'vmf_'
prefix instead of 'vm_' prefix is intended to indicate that it returns a
VMF_ value rather than an errno (which would only have to be converted
into a VMF_ value anyway).

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-09-08 15:35:28 -07:00
Matthew Wilcox fc43704437 mm: export various functions for the benefit of DAX 
To use the huge zero page in DAX, we need these functions exported.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-09-08 15:35:28 -07:00
Matthew Wilcox 4897c7655d thp: prepare for DAX huge pages 
Add a vma_is_dax() helper macro to test whether the VMA is DAX, and use it
in zap_huge_pmd() and __split_huge_page_pmd().

[akpm@linux-foundation.org: fix build]
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-09-08 15:35:28 -07:00
Andrew Morton 7c41416459 dax: revert userfaultfd change 
Undo the change which "userfaultfd: call handle_userfault() for
userfaultfd_missing() faults" made to set_huge_zero_page().  DAX will
need that return value.

Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-09-08 15:35:28 -07:00
Kirill A. Shutemov e1b9996b85 thp: vma_adjust_trans_huge(): adjust file-backed VMA too 
This series of patches adds support for using PMD page table entries to
map DAX files.  We expect NV-DIMMs to start showing up that are many
gigabytes in size and the memory consumption of 4kB PTEs will be
astronomical.

The patch series leverages much of the Transparant Huge Pages
infrastructure, going so far as to borrow one of Kirill's patches from
his THP page cache series.

This patch (of 10):

Since we're going to have huge pages in page cache, we need to call adjust
file-backed VMA, which potentially can contain huge pages.

For now we call it for all VMAs.

Probably later we will need to introduce a flag to indicate that the VMA
has huge pages.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Acked-by: Hillf Danton <dhillf@gmail.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-09-08 15:35:28 -07:00
Andrea Arcangeli 230c92a879 userfaultfd: propagate the full address in THP faults 
The THP faults were not propagating the original fault address.  The
latest version of the API with uffd.arg.pagefault.address is supposed to
propagate the full address through THP faults.

This was not a kernel crashing bug and it wouldn't risk to corrupt user
memory, but it would cause a SIGBUS failure because the wrong page was
being copied.

For various reasons this wasn't easily reproducible in the qemu workload,
but the strestest exposed the problem immediately.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-09-04 16:54:41 -07:00
Andrea Arcangeli c1294d05de userfaultfd: prevent khugepaged to merge if userfaultfd is armed 
If userfaultfd is armed on a certain vma we can't "fill" the holes with
zeroes or we'll break the userland on demand paging.  The holes if the
userfault is armed, are really missing information (not zeroes) that the
userland has to load from network or elsewhere.

The same issue happens for wrprotected ptes that we can't just convert
into a single writable pmd_trans_huge.

We could however in theory still merge across zeropages if only
VM_UFFD_MISSING is set (so if VM_UFFD_WP is not set)...  that could be
slightly improved but it'd be much more complex code for a tiny corner
case.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Cc: Sanidhya Kashyap <sanidhya.gatech@gmail.com>
Cc: zhang.zhanghailiang@huawei.com
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Peter Feiner <pfeiner@google.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Huangpeng (Peter)" <peter.huangpeng@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-09-04 16:54:41 -07:00
Andrea Arcangeli 6b251fc96c userfaultfd: call handle_userfault() for userfaultfd_missing() faults 
This is where the page faults must be modified to call
handle_userfault() if userfaultfd_missing() is true (so if the
vma->vm_flags had VM_UFFD_MISSING set).

handle_userfault() then takes care of blocking the page fault and
delivering it to userland.

The fault flags must also be passed as parameter so the "read|write"
kind of fault can be passed to userland.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Cc: Sanidhya Kashyap <sanidhya.gatech@gmail.com>
Cc: zhang.zhanghailiang@huawei.com
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Peter Feiner <pfeiner@google.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Huangpeng (Peter)" <peter.huangpeng@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-09-04 16:54:41 -07:00
Naoya Horiguchi f4c18e6f7b mm: check __PG_HWPOISON separately from PAGE_FLAGS_CHECK_AT_* 
The race condition addressed in commit add05cecef ("mm: soft-offline:
don't free target page in successful page migration") was not closed
completely, because that can happen not only for soft-offline, but also
for hard-offline.  Consider that a slab page is about to be freed into
buddy pool, and then an uncorrected memory error hits the page just
after entering __free_one_page(), then VM_BUG_ON_PAGE(page->flags &
PAGE_FLAGS_CHECK_AT_PREP) is triggered, despite the fact that it's not
necessary because the data on the affected page is not consumed.

To solve it, this patch drops __PG_HWPOISON from page flag checks at
allocation/free time.  I think it's justified because __PG_HWPOISON
flags is defined to prevent the page from being reused, and setting it
outside the page's alloc-free cycle is a designed behavior (not a bug.)

For recent months, I was annoyed about BUG_ON when soft-offlined page
remains on lru cache list for a while, which is avoided by calling
put_page() instead of putback_lru_page() in page migration's success
path.  This means that this patch reverts a major change from commit
add05cecef about the new refcounting rule of soft-offlined pages, so
"reuse window" revives.  This will be closed by a subsequent patch.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Dean Nelson <dnelson@redhat.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Hugh Dickins <hughd@google.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-08-07 04:39:42 +03:00
Aneesh Kumar K.V 8809aa2d28 mm: clarify that the function operates on hugepage pte 
We have confusing functions to clear pmd, pmd_clear_* and pmd_clear.  Add
_huge_ to pmdp_clear functions so that we are clear that they operate on
hugepage pte.

We don't bother about other functions like pmdp_set_wrprotect,
pmdp_clear_flush_young, because they operate on PTE bits and hence
indicate they are operating on hugepage ptes

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-06-24 17:49:44 -07:00
Aneesh Kumar K.V 15a25b2ead mm/thp: split out pmd collapse flush into separate functions 
Architectures like ppc64 [1] need to do special things while clearing pmd
before a collapse.  For them this operation is largely different from a
normal hugepage pte clear.  Hence add a separate function to clear pmd
before collapse.  After this patch pmdp_* functions operate only on
hugepage pte, and not on regular pmd_t values pointing to page table.

[1] ppc64 needs to invalidate all the normal page pte mappings we already
have inserted in the hardware hash page table.  But before doing that we
need to make sure there are no parallel hash page table insert going on.
So we need to do a kick_all_cpus_sync() before flushing the older hash
table entries.  By moving this to a separate function we capture these
details and mention how it is different from a hugepage pte clear.

This patch is a cleanup and only does code movement for clarity.  There
should not be any change in functionality.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-06-24 17:49:44 -07:00
Jiri Kosina cd09241121 thp: cleanup how khugepaged enters freezer 
khugepaged_do_scan() checks in every iteration whether freezing(current)
is true, and in such case breaks out of the loop, which causes
try_to_freeze() to be called immediately afterwards in
khugepaged_wait_work().

If nothing else, this causes unnecessary freezing(current) test, and also
makes the way khugepaged enters freezer a bit less obvious than necessary.

Let's just try to freeze directly, instead of splitting it into two
(directly adjacent) phases.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-06-24 17:49:41 -07:00
Kirill A. Shutemov 79553da293 thp: cleanup khugepaged startup 
Few trivial cleanups:

 - no need to call set_recommended_min_free_kbytes() from
   late_initcall() -- start_khugepaged() calls it;

 - no need to call set_recommended_min_free_kbytes() from
   start_khugepaged() if khugepaged is not started;

 - there isn't much point in running start_khugepaged() if we've just
   set transparent_hugepage_flags to zero;

 - start_khugepaged() is misnamed -- it also used to stop the thread;

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-04-15 16:35:19 -07:00
Kirill A. Shutemov ae7efa507d thp: do not adjust zone water marks if khugepaged is not started 
set_recommended_min_free_kbytes() adjusts zone water marks to be suitable
for khugepaged. We avoid doing this if khugepaged is disabled, but don't
catch the case when khugepaged is failed to start.

Let's address this by checking khugepaged_thread instead of
khugepaged_enabled() in set_recommended_min_free_kbytes().
It's NULL if the kernel thread is stopped or failed to start.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-04-15 16:35:19 -07:00
Kirill A. Shutemov 65ebb64f4d thp: handle errors in hugepage_init() properly 
We miss error-handling in few cases hugepage_init(). Let's fix that.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-04-15 16:35:18 -07:00
Jason Low 4db0c3c298 mm: remove rest of ACCESS_ONCE() usages 
We converted some of the usages of ACCESS_ONCE to READ_ONCE in the mm/
tree since it doesn't work reliably on non-scalar types.

This patch removes the rest of the usages of ACCESS_ONCE, and use the new
READ_ONCE API for the read accesses.  This makes things cleaner, instead
of using separate/multiple sets of APIs.

Signed-off-by: Jason Low <jason.low2@hp.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Davidlohr Bueso <dave@stgolabs.net>
Acked-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-04-15 16:35:18 -07:00
Michal Hocko 3b3636924d mm, memcg: sync allocation and memcg charge gfp flags for THP 
memcg currently uses hardcoded GFP_TRANSHUGE gfp flags for all THP
charges.  THP allocations, however, might be using different flags
depending on /sys/kernel/mm/transparent_hugepage/{,khugepaged/}defrag and
the current allocation context.

The primary difference is that defrag configured to "madvise" value will
clear __GFP_WAIT flag from the core gfp mask to make the allocation
lighter for all mappings which are not backed by VM_HUGEPAGE vmas.  If
memcg charge path ignores this fact we will get light allocation but the a
potential memcg reclaim would kill the whole point of the configuration.

Fix the mismatch by providing the same gfp mask used for the allocation to
the charge functions.  This is quite easy for all paths except for
hugepaged kernel thread with !CONFIG_NUMA which is doing a pre-allocation
long before the allocated page is used in collapse_huge_page via
khugepaged_alloc_page.  To prevent from cluttering the whole code path
from khugepaged_do_scan we simply return the current flags as per
khugepaged_defrag() value which might have changed since the
preallocation.  If somebody changed the value of the knob we would charge
differently but this shouldn't happen often and it is definitely not
critical because it would only lead to a reduced success rate of one-off
THP promotion.

[akpm@linux-foundation.org: fix weird code layout while we're there]
[rientjes@google.com: clean up around alloc_hugepage_gfpmask()]
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-04-15 16:35:17 -07:00
David Rientjes 5265047ac3 mm, thp: really limit transparent hugepage allocation to local node 
Commit 077fcf116c ("mm/thp: allocate transparent hugepages on local
node") restructured alloc_hugepage_vma() with the intent of only
allocating transparent hugepages locally when there was not an effective
interleave mempolicy.

alloc_pages_exact_node() does not limit the allocation to the single node,
however, but rather prefers it.  This is because __GFP_THISNODE is not set
which would cause the node-local nodemask to be passed.  Without it, only
a nodemask that prefers the local node is passed.

Fix this by passing __GFP_THISNODE and falling back to small pages when
the allocation fails.

Commit 9f1b868a13 ("mm: thp: khugepaged: add policy for finding target
node") suffers from a similar problem for khugepaged, which is also fixed.

Fixes: 077fcf116c ("mm/thp: allocate transparent hugepages on local node")
Fixes: 9f1b868a13 ("mm: thp: khugepaged: add policy for finding target node")
Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Pravin Shelar <pshelar@nicira.com>
Cc: Jarno Rajahalme <jrajahalme@nicira.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-04-14 16:49:03 -07:00
Ebru Akagunduz ca0984caa8 mm: incorporate zero pages into transparent huge pages 
This patch improves THP collapse rates, by allowing zero pages.

Currently THP can collapse 4kB pages into a THP when there are up to
khugepaged_max_ptes_none pte_none ptes in a 2MB range.  This patch counts
pte none and mapped zero pages with the same variable.

The patch was tested with a program that allocates 800MB of
memory, and performs interleaved reads and writes, in a pattern
that causes some 2MB areas to first see read accesses, resulting
in the zero pfn being mapped there.

To simulate memory fragmentation at allocation time, I modified
do_huge_pmd_anonymous_page to return VM_FAULT_FALLBACK for read faults.

Without the patch, only %50 of the program was collapsed into THP and the
percentage did not increase over time.

With this patch after 10 minutes of waiting khugepaged had collapsed %99
of the program's memory.

[aarcange@redhat.com: fix bogus BUG()]
Signed-off-by: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-04-14 16:49:01 -07:00
Kirill A. Shutemov 84d33df279 mm: rename FOLL_MLOCK to FOLL_POPULATE 
After commit a1fde08c74 ("VM: skip the stack guard page lookup in
get_user_pages only for mlock") FOLL_MLOCK has lost its original
meaning: we don't necessarily mlock the page if the flags is set -- we
also take VM_LOCKED into consideration.

Since we use the same codepath for __mm_populate(), let's rename
FOLL_MLOCK to FOLL_POPULATE.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-04-14 16:48:59 -07:00
Mel Gorman b7b04004ec mm: numa: mark huge PTEs young when clearing NUMA hinting faults 
Base PTEs are marked young when the NUMA hinting information is cleared
but the same does not happen for huge pages which this patch addresses.

Note that migrated pages are not marked young as the base page migration
code does not assume that migrated pages have been referenced.  This
could be addressed but beyond the scope of this series which is aimed at
Dave Chinners shrink workload that is unlikely to be affected by this
issue.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-03-25 16:20:31 -07:00
Mel Gorman 074c238177 mm: numa: slow PTE scan rate if migration failures occur 
Dave Chinner reported the following on https://lkml.org/lkml/2015/3/1/226

  Across the board the 4.0-rc1 numbers are much slower, and the degradation
  is far worse when using the large memory footprint configs. Perf points
  straight at the cause - this is from 4.0-rc1 on the "-o bhash=101073" config:

   -   56.07%    56.07%  [kernel]            [k] default_send_IPI_mask_sequence_phys
      - default_send_IPI_mask_sequence_phys
         - 99.99% physflat_send_IPI_mask
            - 99.37% native_send_call_func_ipi
                 smp_call_function_many
               - native_flush_tlb_others
                  - 99.85% flush_tlb_page
                       ptep_clear_flush
                       try_to_unmap_one
                       rmap_walk
                       try_to_unmap
                       migrate_pages
                       migrate_misplaced_page
                     - handle_mm_fault
                        - 99.73% __do_page_fault
                             trace_do_page_fault
                             do_async_page_fault
                           + async_page_fault
              0.63% native_send_call_func_single_ipi
                 generic_exec_single
                 smp_call_function_single

This is showing excessive migration activity even though excessive
migrations are meant to get throttled.  Normally, the scan rate is tuned
on a per-task basis depending on the locality of faults.  However, if
migrations fail for any reason then the PTE scanner may scan faster if
the faults continue to be remote.  This means there is higher system CPU
overhead and fault trapping at exactly the time we know that migrations
cannot happen.  This patch tracks when migration failures occur and
slows the PTE scanner.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reported-by: Dave Chinner <david@fromorbit.com>
Tested-by: Dave Chinner <david@fromorbit.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-03-25 16:20:31 -07:00
Mel Gorman b191f9b106 mm: numa: preserve PTE write permissions across a NUMA hinting fault 
Protecting a PTE to trap a NUMA hinting fault clears the writable bit
and further faults are needed after trapping a NUMA hinting fault to set
the writable bit again.  This patch preserves the writable bit when
trapping NUMA hinting faults.  The impact is obvious from the number of
minor faults trapped during the basis balancing benchmark and the system
CPU usage;

  autonumabench
                                             4.0.0-rc4             4.0.0-rc4
                                              baseline              preserve
  Time System-NUMA01                  107.13 (  0.00%)      103.13 (  3.73%)
  Time System-NUMA01_THEADLOCAL       131.87 (  0.00%)       83.30 ( 36.83%)
  Time System-NUMA02                    8.95 (  0.00%)       10.72 (-19.78%)
  Time System-NUMA02_SMT                4.57 (  0.00%)        3.99 ( 12.69%)
  Time Elapsed-NUMA01                 515.78 (  0.00%)      517.26 ( -0.29%)
  Time Elapsed-NUMA01_THEADLOCAL      384.10 (  0.00%)      384.31 ( -0.05%)
  Time Elapsed-NUMA02                  48.86 (  0.00%)       48.78 (  0.16%)
  Time Elapsed-NUMA02_SMT              47.98 (  0.00%)       48.12 ( -0.29%)

               4.0.0-rc4   4.0.0-rc4
                baseline    preserve
  User          44383.95    43971.89
  System          252.61      201.24
  Elapsed         998.68     1000.94

  Minor Faults   2597249     1981230
  Major Faults       365         364

There is a similar drop in system CPU usage using Dave Chinner's xfsrepair
workload

                                      4.0.0-rc4             4.0.0-rc4
                                       baseline              preserve
  Amean    real-xfsrepair      454.14 (  0.00%)      442.36 (  2.60%)
  Amean    syst-xfsrepair      277.20 (  0.00%)      204.68 ( 26.16%)

The patch looks hacky but the alternatives looked worse.  The tidest was
to rewalk the page tables after a hinting fault but it was more complex
than this approach and the performance was worse.  It's not generally
safe to just mark the page writable during the fault if it's a write
fault as it may have been read-only for COW so that approach was
discarded.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reported-by: Dave Chinner <david@fromorbit.com>
Tested-by: Dave Chinner <david@fromorbit.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-03-25 16:20:31 -07:00
Mel Gorman bea66fbd11 mm: numa: group related processes based on VMA flags instead of page table flags 
These are three follow-on patches based on the xfsrepair workload Dave
Chinner reported was problematic in 4.0-rc1 due to changes in page table
management -- https://lkml.org/lkml/2015/3/1/226.

Much of the problem was reduced by commit 53da3bc2ba ("mm: fix up numa
read-only thread grouping logic") and commit ba68bc0115 ("mm: thp:
Return the correct value for change_huge_pmd").  It was known that the
performance in 3.19 was still better even if is far less safe.  This
series aims to restore the performance without compromising on safety.

For the test of this mail, I'm comparing 3.19 against 4.0-rc4 and the
three patches applied on top

  autonumabench
                                                3.19.0             4.0.0-rc4             4.0.0-rc4             4.0.0-rc4             4.0.0-rc4
                                               vanilla               vanilla          vmwrite-v5r8         preserve-v5r8         slowscan-v5r8
  Time System-NUMA01                  124.00 (  0.00%)      161.86 (-30.53%)      107.13 ( 13.60%)      103.13 ( 16.83%)      145.01 (-16.94%)
  Time System-NUMA01_THEADLOCAL       115.54 (  0.00%)      107.64 (  6.84%)      131.87 (-14.13%)       83.30 ( 27.90%)       92.35 ( 20.07%)
  Time System-NUMA02                    9.35 (  0.00%)       10.44 (-11.66%)        8.95 (  4.28%)       10.72 (-14.65%)        8.16 ( 12.73%)
  Time System-NUMA02_SMT                3.87 (  0.00%)        4.63 (-19.64%)        4.57 (-18.09%)        3.99 ( -3.10%)        3.36 ( 13.18%)
  Time Elapsed-NUMA01                 570.06 (  0.00%)      567.82 (  0.39%)      515.78 (  9.52%)      517.26 (  9.26%)      543.80 (  4.61%)
  Time Elapsed-NUMA01_THEADLOCAL      393.69 (  0.00%)      384.83 (  2.25%)      384.10 (  2.44%)      384.31 (  2.38%)      380.73 (  3.29%)
  Time Elapsed-NUMA02                  49.09 (  0.00%)       49.33 ( -0.49%)       48.86 (  0.47%)       48.78 (  0.63%)       50.94 ( -3.77%)
  Time Elapsed-NUMA02_SMT              47.51 (  0.00%)       47.15 (  0.76%)       47.98 ( -0.99%)       48.12 ( -1.28%)       49.56 ( -4.31%)

                3.19.0   4.0.0-rc4   4.0.0-rc4   4.0.0-rc4   4.0.0-rc4
               vanilla     vanillavmwrite-v5r8preserve-v5r8slowscan-v5r8
  User        46334.60    46391.94    44383.95    43971.89    44372.12
  System        252.84      284.66      252.61      201.24      249.00
  Elapsed      1062.14     1050.96      998.68     1000.94     1026.78

Overall the system CPU usage is comparable and the test is naturally a
bit variable.  The slowing of the scanner hurts numa01 but on this
machine it is an adverse workload and patches that dramatically help it
often hurt absolutely everything else.

Due to patch 2, the fault activity is interesting

                                  3.19.0   4.0.0-rc4   4.0.0-rc4   4.0.0-rc4   4.0.0-rc4
                                 vanilla     vanillavmwrite-v5r8preserve-v5r8slowscan-v5r8
  Minor Faults                   2097811     2656646     2597249     1981230     1636841
  Major Faults                       362         450         365         364         365

Note the impact preserving the write bit across protection updates and
fault reduces faults.

  NUMA alloc hit                 1229008     1217015     1191660     1178322     1199681
  NUMA alloc miss                      0           0           0           0           0
  NUMA interleave hit                  0           0           0           0           0
  NUMA alloc local               1228514     1216317     1190871     1177448     1199021
  NUMA base PTE updates        245706197   240041607   238195516   244704842   115012800
  NUMA huge PMD updates           479530      468448      464868      477573      224487
  NUMA page range updates      491225557   479886983   476207932   489222218   229950144
  NUMA hint faults                659753      656503      641678      656926      294842
  NUMA hint local faults          381604      373963      360478      337585      186249
  NUMA hint local percent             57          56          56          51          63
  NUMA pages migrated            5412140     6374899     6266530     5277468     5755096
  AutoNUMA cost                    5121%       5083%       4994%       5097%       2388%

Here the impact of slowing the PTE scanner on migratrion failures is
obvious as "NUMA base PTE updates" and "NUMA huge PMD updates" are
massively reduced even though the headline performance is very similar.

As xfsrepair was the reported workload here is the impact of the series
on it.

  xfsrepair
                                         3.19.0             4.0.0-rc4             4.0.0-rc4             4.0.0-rc4             4.0.0-rc4
                                        vanilla               vanilla          vmwrite-v5r8         preserve-v5r8         slowscan-v5r8
  Min      real-fsmark        1183.29 (  0.00%)     1165.73 (  1.48%)     1152.78 (  2.58%)     1153.64 (  2.51%)     1177.62 (  0.48%)
  Min      syst-fsmark        4107.85 (  0.00%)     4027.75 (  1.95%)     3986.74 (  2.95%)     3979.16 (  3.13%)     4048.76 (  1.44%)
  Min      real-xfsrepair      441.51 (  0.00%)      463.96 ( -5.08%)      449.50 ( -1.81%)      440.08 (  0.32%)      439.87 (  0.37%)
  Min      syst-xfsrepair      195.76 (  0.00%)      278.47 (-42.25%)      262.34 (-34.01%)      203.70 ( -4.06%)      143.64 ( 26.62%)
  Amean    real-fsmark        1188.30 (  0.00%)     1177.34 (  0.92%)     1157.97 (  2.55%)     1158.21 (  2.53%)     1182.22 (  0.51%)
  Amean    syst-fsmark        4111.37 (  0.00%)     4055.70 (  1.35%)     3987.19 (  3.02%)     3998.72 (  2.74%)     4061.69 (  1.21%)
  Amean    real-xfsrepair      450.88 (  0.00%)      468.32 ( -3.87%)      454.14 ( -0.72%)      442.36 (  1.89%)      440.59 (  2.28%)
  Amean    syst-xfsrepair      199.66 (  0.00%)      290.60 (-45.55%)      277.20 (-38.84%)      204.68 ( -2.51%)      150.55 ( 24.60%)
  Stddev   real-fsmark           4.12 (  0.00%)       10.82 (-162.29%)       4.14 ( -0.28%)        5.98 (-45.05%)        4.60 (-11.53%)
  Stddev   syst-fsmark           2.63 (  0.00%)       20.32 (-671.82%)       0.37 ( 85.89%)       16.47 (-525.59%)      15.05 (-471.79%)
  Stddev   real-xfsrepair        6.87 (  0.00%)        4.55 ( 33.75%)        3.46 ( 49.58%)        1.78 ( 74.12%)        0.52 ( 92.50%)
  Stddev   syst-xfsrepair        3.02 (  0.00%)       10.30 (-241.37%)      13.17 (-336.37%)       0.71 ( 76.63%)        5.00 (-65.61%)
  CoeffVar real-fsmark           0.35 (  0.00%)        0.92 (-164.73%)       0.36 ( -2.91%)        0.52 (-48.82%)        0.39 (-12.10%)
  CoeffVar syst-fsmark           0.06 (  0.00%)        0.50 (-682.41%)       0.01 ( 85.45%)        0.41 (-543.22%)       0.37 (-478.78%)
  CoeffVar real-xfsrepair        1.52 (  0.00%)        0.97 ( 36.21%)        0.76 ( 49.94%)        0.40 ( 73.62%)        0.12 ( 92.33%)
  CoeffVar syst-xfsrepair        1.51 (  0.00%)        3.54 (-134.54%)       4.75 (-214.31%)       0.34 ( 77.20%)        3.32 (-119.63%)
  Max      real-fsmark        1193.39 (  0.00%)     1191.77 (  0.14%)     1162.90 (  2.55%)     1166.66 (  2.24%)     1188.50 (  0.41%)
  Max      syst-fsmark        4114.18 (  0.00%)     4075.45 (  0.94%)     3987.65 (  3.08%)     4019.45 (  2.30%)     4082.80 (  0.76%)
  Max      real-xfsrepair      457.80 (  0.00%)      474.60 ( -3.67%)      457.82 ( -0.00%)      444.42 (  2.92%)      441.03 (  3.66%)
  Max      syst-xfsrepair      203.11 (  0.00%)      303.65 (-49.50%)      294.35 (-44.92%)      205.33 ( -1.09%)      155.28 ( 23.55%)

The really relevant lines as syst-xfsrepair which is the system CPU
usage when running xfsrepair.  Note that on my machine the overhead was
45% higher on 4.0-rc4 which may be part of what Dave is seeing.  Once we
preserve the write bit across faults, it's only 2.51% higher on average.
With the full series applied, system CPU usage is 24.6% lower on
average.

Again, the impact of preserving the write bit on minor faults is obvious
and the impact of slowing scanning after migration failures is obvious
on the PTE updates.  Note also that the number of pages migrated is much
reduced even though the headline performance is comparable.

                                  3.19.0   4.0.0-rc4   4.0.0-rc4   4.0.0-rc4   4.0.0-rc4
                                 vanilla     vanillavmwrite-v5r8preserve-v5r8slowscan-v5r8
  Minor Faults                 153466827   254507978   249163829   153501373   105737890
  Major Faults                       610         702         690         649         724
  NUMA base PTE updates        217735049   210756527   217729596   216937111   144344993
  NUMA huge PMD updates           129294       85044      106921      127246       79887
  NUMA pages migrated           21938995    29705270    28594162    22687324    16258075

                        3.19.0   4.0.0-rc4   4.0.0-rc4   4.0.0-rc4   4.0.0-rc4
                       vanilla     vanillavmwrite-v5r8preserve-v5r8slowscan-v5r8
  Mean sdb-avgqusz       13.47        2.54        2.55        2.47        2.49
  Mean sdb-avgrqsz      202.32      140.22      139.50      139.02      138.12
  Mean sdb-await         25.92        5.09        5.33        5.02        5.22
  Mean sdb-r_await        4.71        0.19        0.83        0.51        0.11
  Mean sdb-w_await      104.13        5.21        5.38        5.05        5.32
  Mean sdb-svctm          0.59        0.13        0.14        0.13        0.14
  Mean sdb-rrqm           0.16        0.00        0.00        0.00        0.00
  Mean sdb-wrqm           3.59     1799.43     1826.84     1812.21     1785.67
  Max  sdb-avgqusz      111.06       12.13       14.05       11.66       15.60
  Max  sdb-avgrqsz      255.60      190.34      190.01      187.33      191.78
  Max  sdb-await        168.24       39.28       49.22       44.64       65.62
  Max  sdb-r_await      660.00       52.00      280.00       76.00       12.00
  Max  sdb-w_await     7804.00       39.28       49.22       44.64       65.62
  Max  sdb-svctm          4.00        2.82        2.86        1.98        2.84
  Max  sdb-rrqm           8.30        0.00        0.00        0.00        0.00
  Max  sdb-wrqm          34.20     5372.80     5278.60     5386.60     5546.15

FWIW, I also checked SPECjbb in different configurations but it's
similar observations -- minor faults lower, PTE update activity lower
and performance is roughly comparable against 3.19.

This patch (of 3):

Threads that share writable data within pages are grouped together as
related tasks.  This decision is based on whether the PTE is marked
dirty which is subject to timing races between the PTE scanner update
and when the application writes the page.  If the page is file-backed,
then background flushes and sync also affect placement.  This is
unpredictable behaviour which is impossible to reason about so this
patch makes grouping decisions based on the VMA flags.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reported-by: Dave Chinner <david@fromorbit.com>
Tested-by: Dave Chinner <david@fromorbit.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-03-25 16:20:31 -07:00
Mel Gorman ba68bc0115 mm: thp: Return the correct value for change_huge_pmd 
The wrong value is being returned by change_huge_pmd since commit
10c1045f28 ("mm: numa: avoid unnecessary TLB flushes when setting
NUMA hinting entries") which allows a fallthrough that tries to adjust
non-existent PTEs. This patch corrects it.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-03-12 14:07:41 -07:00
Linus Torvalds 53da3bc2ba mm: fix up numa read-only thread grouping logic 
Dave Chinner reported that commit 4d94246699 ("mm: convert
p[te|md]_mknonnuma and remaining page table manipulations") slowed down
his xfsrepair test enormously.  In particular, it was using more system
time due to extra TLB flushing.

The ultimate reason turns out to be how the change to use the regular
page table accessor functions broke the NUMA grouping logic.  The old
special mknuma/mknonnuma code accessed the page table present bit and
the magic NUMA bit directly, while the new code just changes the page
protections using PROT_NONE and the regular vma protections.

That sounds equivalent, and from a fault standpoint it really is, but a
subtle side effect is that the *other* protection bits of the page table
entries also change.  And the code to decide how to group the NUMA
entries together used the writable bit to decide whether a particular
page was likely to be shared read-only or not.

And with the change to make the NUMA handling use the regular permission
setting functions, that writable bit was basically always cleared for
private mappings due to COW.  So even if the page actually ends up being
written to in the end, the NUMA balancing would act as if it was always
shared RO.

This code is a heuristic anyway, so the fix - at least for now - is to
instead check whether the page is dirty rather than writable.  The bit
doesn't change with protection changes.

NOTE! This also adds a FIXME comment to revisit this issue,

Not only should we probably re-visit the whole "is this a shared
read-only page" heuristic (we might want to take the vma permissions
into account and base this more on those than the per-page ones, and
also look at whether the particular access that triggers it is a write
or not), but the whole COW issue shows that we should think about the
NUMA fault handling some more.

For example, maybe we should do the early-COW thing that a regular fault
does.  Or maybe we should accept that while using the same bits as
PROTNONE was a good thing (and got rid of the specual NUMA bit), we
might still want to just preseve the other protection bits across NUMA
faulting.

Those are bigger questions, left for later.  This just fixes up the
heuristic so that it at least approximates working again.  More analysis
and work needed.

Reported-by: Dave Chinner <david@fromorbit.com>
Tested-by: Mel Gorman <mgorman@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>,
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-03-12 08:45:46 -07:00
Mel Gorman 10c1045f28 mm: numa: avoid unnecessary TLB flushes when setting NUMA hinting entries 
If a PTE or PMD is already marked NUMA when scanning to mark entries for
NUMA hinting then it is not necessary to update the entry and incur a TLB
flush penalty.  Avoid the avoidhead where possible.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-02-12 18:54:08 -08:00
Mel Gorman c0e7cad9f2 mm: numa: add paranoid check around pte_protnone_numa 
pte_protnone_numa is only safe to use after VMA checks for PROT_NONE are
complete.  Treating a real PROT_NONE PTE as a NUMA hinting fault is going
to result in strangeness so add a check for it.  BUG_ON looks like
overkill but if this is hit then it's a serious bug that could result in
corruption so do not even try recovering.  It would have been more
comprehensive to check VMA flags in pte_protnone_numa but it would have
made the API ugly just for a debugging check.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-02-12 18:54:08 -08:00
Mel Gorman e944fd67b6 mm: numa: do not trap faults on the huge zero page 
Faults on the huge zero page are pointless and there is a BUG_ON to catch
them during fault time.  This patch reintroduces a check that avoids
marking the zero page PAGE_NONE.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-02-12 18:54:08 -08:00
Mel Gorman 4d94246699 mm: convert p[te|md]_mknonnuma and remaining page table manipulations 
With PROT_NONE, the traditional page table manipulation functions are
sufficient.

[andre.przywara@arm.com: fix compiler warning in pmdp_invalidate()]
[akpm@linux-foundation.org: fix build with STRICT_MM_TYPECHECKS]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-02-12 18:54:08 -08:00
Mel Gorman 8a0516ed8b mm: convert p[te|md]_numa users to p[te|md]_protnone_numa 
Convert existing users of pte_numa and friends to the new helper.  Note
that the kernel is broken after this patch is applied until the other page
table modifiers are also altered.  This patch layout is to make review
easier.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-02-12 18:54:08 -08:00
Mel Gorman 5d83306213 mm: numa: do not dereference pmd outside of the lock during NUMA hinting fault 
Automatic NUMA balancing depends on being able to protect PTEs to trap a
fault and gather reference locality information.  Very broadly speaking
it would mark PTEs as not present and use another bit to distinguish
between NUMA hinting faults and other types of faults.  It was
universally loved by everybody and caused no problems whatsoever.  That
last sentence might be a lie.

This series is very heavily based on patches from Linus and Aneesh to
replace the existing PTE/PMD NUMA helper functions with normal change
protections.  I did alter and add parts of it but I consider them
relatively minor contributions.  At their suggestion, acked-bys are in
there but I've no problem converting them to Signed-off-by if requested.

AFAIK, this has received no testing on ppc64 and I'm depending on Aneesh
for that.  I tested trinity under kvm-tool and passed and ran a few
other basic tests.  At the time of writing, only the short-lived tests
have completed but testing of V2 indicated that long-term testing had no
surprises.  In most cases I'm leaving out detail as it's not that
interesting.

specjbb single JVM: There was negligible performance difference in the
	benchmark itself for short runs. However, system activity is
	higher and interrupts are much higher over time -- possibly TLB
	flushes. Migrations are also higher. Overall, this is more overhead
	but considering the problems faced with the old approach I think
	we just have to suck it up and find another way of reducing the
	overhead.

specjbb multi JVM: Negligible performance difference to the actual benchmark
	but like the single JVM case, the system overhead is noticeably
	higher.  Again, interrupts are a major factor.

autonumabench: This was all over the place and about all that can be
	reasonably concluded is that it's different but not necessarily
	better or worse.

autonumabench
                                     3.18.0-rc5            3.18.0-rc5
                                 mmotm-20141119         protnone-v3r3
User    NUMA01               32380.24 (  0.00%)    21642.92 ( 33.16%)
User    NUMA01_THEADLOCAL    22481.02 (  0.00%)    22283.22 (  0.88%)
User    NUMA02                3137.00 (  0.00%)     3116.54 (  0.65%)
User    NUMA02_SMT            1614.03 (  0.00%)     1543.53 (  4.37%)
System  NUMA01                 322.97 (  0.00%)     1465.89 (-353.88%)
System  NUMA01_THEADLOCAL       91.87 (  0.00%)       49.32 ( 46.32%)
System  NUMA02                  37.83 (  0.00%)       14.61 ( 61.38%)
System  NUMA02_SMT               7.36 (  0.00%)        7.45 ( -1.22%)
Elapsed NUMA01                 716.63 (  0.00%)      599.29 ( 16.37%)
Elapsed NUMA01_THEADLOCAL      553.98 (  0.00%)      539.94 (  2.53%)
Elapsed NUMA02                  83.85 (  0.00%)       83.04 (  0.97%)
Elapsed NUMA02_SMT              86.57 (  0.00%)       79.15 (  8.57%)
CPU     NUMA01                4563.00 (  0.00%)     3855.00 ( 15.52%)
CPU     NUMA01_THEADLOCAL     4074.00 (  0.00%)     4136.00 ( -1.52%)
CPU     NUMA02                3785.00 (  0.00%)     3770.00 (  0.40%)
CPU     NUMA02_SMT            1872.00 (  0.00%)     1959.00 ( -4.65%)

System CPU usage of NUMA01 is worse but it's an adverse workload on this
machine so I'm reluctant to conclude that it's a problem that matters.  On
the other workloads that are sensible on this machine, system CPU usage is
great.  Overall time to complete the benchmark is comparable

          3.18.0-rc5  3.18.0-rc5
        mmotm-20141119protnone-v3r3
User        59612.50    48586.44
System        460.22     1537.45
Elapsed      1442.20     1304.29

NUMA alloc hit                 5075182     5743353
NUMA alloc miss                      0           0
NUMA interleave hit                  0           0
NUMA alloc local               5075174     5743339
NUMA base PTE updates        637061448   443106883
NUMA huge PMD updates          1243434      864747
NUMA page range updates     1273699656   885857347
NUMA hint faults               1658116     1214277
NUMA hint local faults          959487      754113
NUMA hint local percent             57          62
NUMA pages migrated            5467056    61676398

The NUMA pages migrated look terrible but when I looked at a graph of the
activity over time I see that the massive spike in migration activity was
during NUMA01.  This correlates with high system CPU usage and could be
simply down to bad luck but any modifications that affect that workload
would be related to scan rates and migrations, not the protection
mechanism.  For all other workloads, migration activity was comparable.

Overall, headline performance figures are comparable but the overhead is
higher, mostly in interrupts.  To some extent, higher overhead from this
approach was anticipated but not to this degree.  It's going to be
necessary to reduce this again with a separate series in the future.  It's
still worth going ahead with this series though as it's likely to avoid
constant headaches with Xen and is probably easier to maintain.

This patch (of 10):

A transhuge NUMA hinting fault may find the page is migrating and should
wait until migration completes.  The check is race-prone because the pmd
is deferenced outside of the page lock and while the race is tiny, it'll
be larger if the PMD is cleared while marking PMDs for hinting fault.
This patch closes the race.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-02-12 18:54:08 -08:00
Ebru Akagunduz 10359213d0 mm: incorporate read-only pages into transparent huge pages 
This patch aims to improve THP collapse rates, by allowing THP collapse in
the presence of read-only ptes, like those left in place by do_swap_page
after a read fault.

Currently THP can collapse 4kB pages into a THP when there are up to
khugepaged_max_ptes_none pte_none ptes in a 2MB range.  This patch applies
the same limit for read-only ptes.

The patch was tested with a test program that allocates 800MB of memory,
writes to it, and then sleeps.  I force the system to swap out all but
190MB of the program by touching other memory.  Afterwards, the test
program does a mix of reads and writes to its memory, and the memory gets
swapped back in.

Without the patch, only the memory that did not get swapped out remained
in THPs, which corresponds to 24% of the memory of the program.  The
percentage did not increase over time.

With this patch, after 5 minutes of waiting khugepaged had collapsed 50%
of the program's memory back into THPs.

Test results:

With the patch:
After swapped out:
cat /proc/pid/smaps:
Anonymous:      100464 kB
AnonHugePages:  100352 kB
Swap:           699540 kB
Fraction:       99,88

cat /proc/meminfo:
AnonPages:      1754448 kB
AnonHugePages:  1716224 kB
Fraction:       97,82

After swapped in:
In a few seconds:
cat /proc/pid/smaps:
Anonymous:      800004 kB
AnonHugePages:  145408 kB
Swap:           0 kB
Fraction:       18,17

cat /proc/meminfo:
AnonPages:      2455016 kB
AnonHugePages:  1761280 kB
Fraction:       71,74

In 5 minutes:
cat /proc/pid/smaps
Anonymous:      800004 kB
AnonHugePages:  407552 kB
Swap:           0 kB
Fraction:       50,94

cat /proc/meminfo:
AnonPages:      2456872 kB
AnonHugePages:  2023424 kB
Fraction:       82,35

Without the patch:
After swapped out:
cat /proc/pid/smaps:
Anonymous:      190660 kB
AnonHugePages:  190464 kB
Swap:           609344 kB
Fraction:       99,89

cat /proc/meminfo:
AnonPages:      1740456 kB
AnonHugePages:  1667072 kB
Fraction:       95,78

After swapped in:
cat /proc/pid/smaps:
Anonymous:      800004 kB
AnonHugePages:  190464 kB
Swap:           0 kB
Fraction:       23,80

cat /proc/meminfo:
AnonPages:      2350032 kB
AnonHugePages:  1667072 kB
Fraction:       70,93

I waited 10 minutes the fractions did not change without the patch.

Signed-off-by: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Acked-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-02-11 17:06:07 -08:00
Naoya Horiguchi 1e25a271c8 mincore: apply page table walker on do_mincore() 
This patch makes do_mincore() use walk_page_vma(), which reduces many
lines of code by using common page table walk code.

[daeseok.youn@gmail.com: remove unneeded variable 'err']
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Daeseok Youn <daeseok.youn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-02-11 17:06:06 -08:00
Aneesh Kumar K.V 077fcf116c mm/thp: allocate transparent hugepages on local node 
This make sure that we try to allocate hugepages from local node if
allowed by mempolicy.  If we can't, we fallback to small page allocation
based on mempolicy.  This is based on the observation that allocating
pages on local node is more beneficial than allocating hugepages on remote
node.

With this patch applied we may find transparent huge page allocation
failures if the current node doesn't have enough freee hugepages.  Before
this patch such failures result in us retrying the allocation on other
nodes in the numa node mask.

[akpm@linux-foundation.org: fix comment, add CONFIG_TRANSPARENT_HUGEPAGE dependency]
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-02-11 17:06:04 -08:00
Wang, Yalin 56873f43ab mm:add KPF_ZERO_PAGE flag for /proc/kpageflags 
Add KPF_ZERO_PAGE flag for zero_page, so that userspace processes can
detect zero_page in /proc/kpageflags, and then do memory analysis more
accurately.

Signed-off-by: Yalin Wang <yalin.wang@sonymobile.com>
Acked-by: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2015-02-11 17:06:00 -08:00
Linus Torvalds 988adfdffd Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux 
Pull drm updates from Dave Airlie:
 "Highlights:

   - AMD KFD driver merge

     This is the AMD HSA interface for exposing a lowlevel interface for
     GPGPU use.  They have an open source userspace built on top of this
     interface, and the code looks as good as it was going to get out of
     tree.

   - Initial atomic modesetting work

     The need for an atomic modesetting interface to allow userspace to
     try and send a complete set of modesetting state to the driver has
     arisen, and been suffering from neglect this past year.  No more,
     the start of the common code and changes for msm driver to use it
     are in this tree.  Ongoing work to get the userspace ioctl finished
     and the code clean will probably wait until next kernel.

   - DisplayID 1.3 and tiled monitor exposed to userspace.

     Tiled monitor property is now exposed for userspace to make use of.

   - Rockchip drm driver merged.

   - imx gpu driver moved out of staging

  Other stuff:

   - core:
        panel - MIPI DSI + new panels.
        expose suggested x/y properties for virtual GPUs

   - i915:
        Initial Skylake (SKL) support
        gen3/4 reset work
        start of dri1/ums removal
        infoframe tracking
        fixes for lots of things.

   - nouveau:
        tegra k1 voltage support
        GM204 modesetting support
        GT21x memory reclocking work

   - radeon:
        CI dpm fixes
        GPUVM improvements
        Initial DPM fan control

   - rcar-du:
        HDMI support added
        removed some support for old boards
        slave encoder driver for Analog Devices adv7511

   - exynos:
        Exynos4415 SoC support

   - msm:
        a4xx gpu support
        atomic helper conversion

   - tegra:
        iommu support
        universal plane support
        ganged-mode DSI support

   - sti:
        HDMI i2c improvements

   - vmwgfx:
        some late fixes.

   - qxl:
        use suggested x/y properties"

* 'drm-next' of git://people.freedesktop.org/~airlied/linux: (969 commits)
  drm: sti: fix module compilation issue
  drm/i915: save/restore GMBUS freq across suspend/resume on gen4
  drm: sti: correctly cleanup CRTC and planes
  drm: sti: add HQVDP plane
  drm: sti: add cursor plane
  drm: sti: enable auxiliary CRTC
  drm: sti: fix delay in VTG programming
  drm: sti: prepare sti_tvout to support auxiliary crtc
  drm: sti: use drm_crtc_vblank_{on/off} instead of drm_vblank_{on/off}
  drm: sti: fix hdmi avi infoframe
  drm: sti: remove event lock while disabling vblank
  drm: sti: simplify gdp code
  drm: sti: clear all mixer control
  drm: sti: remove gpio for HDMI hot plug detection
  drm: sti: allow to change hdmi ddc i2c adapter
  drm/doc: Document drm_add_modes_noedid() usage
  drm/i915: Remove '& 0xffff' from the mask given to WA_REG()
  drm/i915: Invert the mask and val arguments in wa_add() and WA_REG()
  drm: Zero out DRM object memory upon cleanup
  drm/i915/bdw: Fix the write setting up the WIZ hashing mode
  ...
 2014-12-15 15:52:01 -08:00
Linus Torvalds 27afc5dbda Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux 
Pull s390 updates from Martin Schwidefsky:
 "The most notable change for this pull request is the ftrace rework
  from Heiko.  It brings a small performance improvement and the ground
  work to support a new gcc option to replace the mcount blocks with a
  single nop.

  Two new s390 specific system calls are added to emulate user space
  mmio for PCI, an artifact of the how PCI memory is accessed.

  Two patches for the memory management with changes to common code.
  For KVM mm_forbids_zeropage is added which disables the empty zero
  page for an mm that is used by a KVM process.  And an optimization,
  pmdp_get_and_clear_full is added analog to ptep_get_and_clear_full.

  Some micro optimization for the cmpxchg and the spinlock code.

  And as usual bug fixes and cleanups"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (46 commits)
  s390/cputime: fix 31-bit compile
  s390/scm_block: make the number of reqs per HW req configurable
  s390/scm_block: handle multiple requests in one HW request
  s390/scm_block: allocate aidaw pages only when necessary
  s390/scm_block: use mempool to manage aidaw requests
  s390/eadm: change timeout value
  s390/mm: fix memory leak of ptlock in pmd_free_tlb
  s390: use local symbol names in entry[64].S
  s390/ptrace: always include vector registers in core files
  s390/simd: clear vector register pointer on fork/clone
  s390: translate cputime magic constants to macros
  s390/idle: convert open coded idle time seqcount
  s390/idle: add missing irq off lockdep annotation
  s390/debug: avoid function call for debug_sprintf_*
  s390/kprobes: fix instruction copy for out of line execution
  s390: remove diag 44 calls from cpu_relax()
  s390/dasd: retry partition detection
  s390/dasd: fix list corruption for sleep_on requests
  s390/dasd: fix infinite term I/O loop
  s390/dasd: remove unused code
  ...
 2014-12-11 17:30:55 -08:00
Kirill A. Shutemov e544a4e74e thp: do not mark zero-page pmd write-protected explicitly 
Zero pages can be used only in anonymous mappings, which never have
writable vma->vm_page_prot: see protection_map in mm/mmap.c and __PX1X
definitions.

Let's drop redundant pmd_wrprotect() in set_huge_zero_page().

Signed-off-by: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-12-10 17:41:08 -08:00
David Rientjes 6d50e60cd2 mm, thp: fix collapsing of hugepages on madvise 
If an anonymous mapping is not allowed to fault thp memory and then
madvise(MADV_HUGEPAGE) is used after fault, khugepaged will never
collapse this memory into thp memory.

This occurs because the madvise(2) handler for thp, hugepage_madvise(),
clears VM_NOHUGEPAGE on the stack and it isn't stored in vma->vm_flags
until the final action of madvise_behavior().  This causes the
khugepaged_enter_vma_merge() to be a no-op in hugepage_madvise() when
the vma had previously had VM_NOHUGEPAGE set.

Fix this by passing the correct vma flags to the khugepaged mm slot
handler.  There's no chance khugepaged can run on this vma until after
madvise_behavior() returns since we hold mm->mmap_sem.

It would be possible to clear VM_NOHUGEPAGE directly from vma->vm_flags
in hugepage_advise(), but I didn't want to introduce special case
behavior into madvise_behavior().  I think it's best to just let it
always set vma->vm_flags itself.

Signed-off-by: David Rientjes <rientjes@google.com>
Reported-by: Suleiman Souhlal <suleiman@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-10-29 16:33:14 -07:00
Yu Zhao 5ddacbe92b mm: free compound page with correct order 
Compound page should be freed by put_page() or free_pages() with correct
order.  Not doing so will cause tail pages leaked.

The compound order can be obtained by compound_order() or use
HPAGE_PMD_ORDER in our case.  Some people would argue the latter is
faster but I prefer the former which is more general.

This bug was observed not just on our servers (the worst case we saw is
11G leaked on a 48G machine) but also on our workstations running Ubuntu
based distro.

  $ cat /proc/vmstat  | grep thp_zero_page_alloc
  thp_zero_page_alloc 55
  thp_zero_page_alloc_failed 0

This means there is (thp_zero_page_alloc - 1) * (2M - 4K) memory leaked.

Fixes: 97ae17497e ("thp: implement refcounting for huge zero page")
Signed-off-by: Yu Zhao <yuzhao@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: David Rientjes <rientjes@google.com>
Cc: Bob Liu <lliubbo@gmail.com>
Cc: <stable@vger.kernel.org>	[3.8+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-10-29 16:33:14 -07:00
Martin Schwidefsky fcbe08d66f s390/mm: pmdp_get_and_clear_full optimization 
Analog to ptep_get_and_clear_full define a variant of the
pmpd_get_and_clear primitive which gets the full hint from the
mmu_gather struct. This allows s390 to avoid a costly instruction
when destroying an address space.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
 2014-10-27 13:27:30 +01:00
Dominik Dingel 593befa6ab mm: introduce mm_forbids_zeropage function 
Add a new function stub to allow architectures to disable for
an mm_structthe backing of non-present, anonymous pages with
read-only empty zero pages.

Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
 2014-10-27 13:27:24 +01:00
Sasha Levin 96dad67ff2 mm: use VM_BUG_ON_MM where possible 
Dump the contents of the relevant struct_mm when we hit the bug condition.

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-10-09 22:25:58 -04:00
Sasha Levin 81d1b09c6b mm: convert a few VM_BUG_ON callers to VM_BUG_ON_VMA 
Trivially convert a few VM_BUG_ON calls to VM_BUG_ON_VMA to extract
more information when they trigger.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michel Lespinasse <walken@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-10-09 22:25:57 -04:00
Vlastimil Babka 8b1645685a mm, THP: don't hold mmap_sem in khugepaged when allocating THP 
When allocating huge page for collapsing, khugepaged currently holds
mmap_sem for reading on the mm where collapsing occurs.  Afterwards the
read lock is dropped before write lock is taken on the same mmap_sem.

Holding mmap_sem during whole huge page allocation is therefore useless,
the vma needs to be rechecked after taking the write lock anyway.
Furthemore, huge page allocation might involve a rather long sync
compaction, and thus block any mmap_sem writers and i.e.  affect workloads
that perform frequent m(un)map or mprotect oterations.

This patch simply releases the read lock before allocating a huge page.
It also deletes an outdated comment that assumed vma must be stable, as it
was using alloc_hugepage_vma().  This is no longer true since commit
9f1b868a13 ("mm: thp: khugepaged: add policy for finding target node").

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-10-09 22:25:53 -04:00
Mel Gorman abc40bd2ee mm: numa: Do not mark PTEs pte_numa when splitting huge pages 
This patch reverts 1ba6e0b50b ("mm: numa: split_huge_page: transfer the
NUMA type from the pmd to the pte"). If a huge page is being split due
a protection change and the tail will be in a PROT_NONE vma then NUMA
hinting PTEs are temporarily created in the protected VMA.

 VM_RW|VM_PROTNONE
|-----------------|
      ^
      split here

In the specific case above, it should get fixed up by change_pte_range()
but there is a window of opportunity for weirdness to happen. Similarly,
if a huge page is shrunk and split during a protection update but before
pmd_numa is cleared then a pte_numa can be left behind.

Instead of adding complexity trying to deal with the case, this patch
will not mark PTEs NUMA when splitting a huge page. NUMA hinting faults
will not be triggered which is marginal in comparison to the complexity
in dealing with the corner cases during THP split.

Cc: stable@vger.kernel.org
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-10-02 11:57:18 -07:00
Johannes Weiner 00501b531c mm: memcontrol: rewrite charge API 
These patches rework memcg charge lifetime to integrate more naturally
with the lifetime of user pages.  This drastically simplifies the code and
reduces charging and uncharging overhead.  The most expensive part of
charging and uncharging is the page_cgroup bit spinlock, which is removed
entirely after this series.

Here are the top-10 profile entries of a stress test that reads a 128G
sparse file on a freshly booted box, without even a dedicated cgroup (i.e.
 executing in the root memcg).  Before:

    15.36%              cat  [kernel.kallsyms]   [k] copy_user_generic_string
    13.31%              cat  [kernel.kallsyms]   [k] memset
    11.48%              cat  [kernel.kallsyms]   [k] do_mpage_readpage
     4.23%              cat  [kernel.kallsyms]   [k] get_page_from_freelist
     2.38%              cat  [kernel.kallsyms]   [k] put_page
     2.32%              cat  [kernel.kallsyms]   [k] __mem_cgroup_commit_charge
     2.18%          kswapd0  [kernel.kallsyms]   [k] __mem_cgroup_uncharge_common
     1.92%          kswapd0  [kernel.kallsyms]   [k] shrink_page_list
     1.86%              cat  [kernel.kallsyms]   [k] __radix_tree_lookup
     1.62%              cat  [kernel.kallsyms]   [k] __pagevec_lru_add_fn

After:

    15.67%           cat  [kernel.kallsyms]   [k] copy_user_generic_string
    13.48%           cat  [kernel.kallsyms]   [k] memset
    11.42%           cat  [kernel.kallsyms]   [k] do_mpage_readpage
     3.98%           cat  [kernel.kallsyms]   [k] get_page_from_freelist
     2.46%           cat  [kernel.kallsyms]   [k] put_page
     2.13%       kswapd0  [kernel.kallsyms]   [k] shrink_page_list
     1.88%           cat  [kernel.kallsyms]   [k] __radix_tree_lookup
     1.67%           cat  [kernel.kallsyms]   [k] __pagevec_lru_add_fn
     1.39%       kswapd0  [kernel.kallsyms]   [k] free_pcppages_bulk
     1.30%           cat  [kernel.kallsyms]   [k] kfree

As you can see, the memcg footprint has shrunk quite a bit.

   text    data     bss     dec     hex filename
  37970    9892     400   48262    bc86 mm/memcontrol.o.old
  35239    9892     400   45531    b1db mm/memcontrol.o

This patch (of 4):

The memcg charge API charges pages before they are rmapped - i.e.  have an
actual "type" - and so every callsite needs its own set of charge and
uncharge functions to know what type is being operated on.  Worse,
uncharge has to happen from a context that is still type-specific, rather
than at the end of the page's lifetime with exclusive access, and so
requires a lot of synchronization.

Rewrite the charge API to provide a generic set of try_charge(),
commit_charge() and cancel_charge() transaction operations, much like
what's currently done for swap-in:

  mem_cgroup_try_charge() attempts to reserve a charge, reclaiming
  pages from the memcg if necessary.

  mem_cgroup_commit_charge() commits the page to the charge once it
  has a valid page->mapping and PageAnon() reliably tells the type.

  mem_cgroup_cancel_charge() aborts the transaction.

This reduces the charge API and enables subsequent patches to
drastically simplify uncharging.

As pages need to be committed after rmap is established but before they
are added to the LRU, page_add_new_anon_rmap() must stop doing LRU
additions again.  Revive lru_cache_add_active_or_unevictable().

[hughd@google.com: fix shmem_unuse]
[hughd@google.com: Add comments on the private use of -EAGAIN]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-08-08 15:57:17 -07:00
David Rientjes 14a4e2141e mm, thp: only collapse hugepages to nodes with affinity for zone_reclaim_mode 
Commit 9f1b868a13 ("mm: thp: khugepaged: add policy for finding target
node") improved the previous khugepaged logic which allocated a
transparent hugepages from the node of the first page being collapsed.

However, it is still possible to collapse pages to remote memory which
may suffer from additional access latency.  With the current policy, it
is possible that 255 pages (with PAGE_SHIFT == 12) will be collapsed
remotely if the majority are allocated from that node.

When zone_reclaim_mode is enabled, it means the VM should make every
attempt to allocate locally to prevent NUMA performance degradation.  In
this case, we do not want to collapse hugepages to remote nodes that
would suffer from increased access latency.  Thus, when
zone_reclaim_mode is enabled, only allow collapsing to nodes with
RECLAIM_DISTANCE or less.

There is no functional change for systems that disable
zone_reclaim_mode.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Bob Liu <bob.liu@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-08-06 18:01:20 -07:00
Johannes Weiner d51d885bbb mm: huge_memory: use GFP_TRANSHUGE when charging huge pages 
Transparent huge page charges prefer falling back to regular pages
rather than spending a lot of time in direct reclaim.

Desired reclaim behavior is usually declared in the gfp mask, but THP
charges use GFP_KERNEL and then rely on the fact that OOM is disabled
for THP charges, and that OOM-disabled charges don't retry reclaim.
Needless to say, this is anything but obvious and quite error prone.

Convert THP charges to use GFP_TRANSHUGE instead, which implies
__GFP_NORETRY, to indicate the low-latency requirement.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-08-06 18:01:17 -07:00
Waiman Long 3a79d52aa3 mm, thp: replace smp_mb after atomic_add by smp_mb__after_atomic 
In some architectures like x86, atomic_add() is a full memory barrier.
In that case, an additional smp_mb() is just a waste of time.  This
patch replaces that smp_mb() by smp_mb__after_atomic() which will avoid
the redundant memory barrier in some architectures.

With a 3.16-rc1 based kernel, this patch reduced the execution time of
breaking 1000 transparent huge pages from 38,245us to 30,964us.  A
reduction of 19% which is quite sizeable.  It also reduces the %cpu time
of the __split_huge_page_refcount function in the perf profile from
2.18% to 1.15%.

Signed-off-by: Waiman Long <Waiman.Long@hp.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Scott J Norton <scott.norton@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-08-06 18:01:17 -07:00
Waiman Long f8303c2582 mm, thp: move invariant bug check out of loop in __split_huge_page_map 
In __split_huge_page_map(), the check for page_mapcount(page) is
invariant within the for loop.  Because of the fact that the macro is
implemented using atomic_read(), the redundant check cannot be optimized
away by the compiler leading to unnecessary read to the page structure.

This patch moves the invariant bug check out of the loop so that it will
be done only once.  On a 3.16-rc1 based kernel, the execution time of a
microbenchmark that broke up 1000 transparent huge pages using munmap()
had an execution time of 38,245us and 38,548us with and without the
patch respectively.  The performance gain is about 1%.

Signed-off-by: Waiman Long <Waiman.Long@hp.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Scott J Norton <scott.norton@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-08-06 18:01:16 -07:00
Hugh Dickins f72e7dcdd2 mm: let mm_find_pmd fix buggy race with THP fault 
Trinity has reported:

    BUG: unable to handle kernel NULL pointer dereference at 0000000000000018
    IP: __lock_acquire (kernel/locking/lockdep.c:3070 (discriminator 1))
    CPU: 6 PID: 16173 Comm: trinity-c364 Tainted: G        W
                            3.15.0-rc1-next-20140415-sasha-00020-gaa90d09 #398
    lock_acquire (arch/x86/include/asm/current.h:14
                  kernel/locking/lockdep.c:3602)
    _raw_spin_lock (include/linux/spinlock_api_smp.h:143
                    kernel/locking/spinlock.c:151)
    remove_migration_pte (mm/migrate.c:137)
    rmap_walk (mm/rmap.c:1628 mm/rmap.c:1699)
    remove_migration_ptes (mm/migrate.c:224)
    migrate_pages (mm/migrate.c:922 mm/migrate.c:960 mm/migrate.c:1126)
    migrate_misplaced_page (mm/migrate.c:1733)
    __handle_mm_fault (mm/memory.c:3762 mm/memory.c:3812 mm/memory.c:3925)
    handle_mm_fault (mm/memory.c:3948)
    __get_user_pages (mm/memory.c:1851)
    __mlock_vma_pages_range (mm/mlock.c:255)
    __mm_populate (mm/mlock.c:711)
    SyS_mlockall (include/linux/mm.h:1799 mm/mlock.c:817 mm/mlock.c:791)

I believe this comes about because, whereas collapsing and splitting THP
functions take anon_vma lock in write mode (which excludes concurrent
rmap walks), faulting THP functions (write protection and misplaced
NUMA) do not - and mostly they do not need to.

But they do use a pmdp_clear_flush(), set_pmd_at() sequence which, for
an instant (indeed, for a long instant, given the inter-CPU TLB flush in
there), leaves *pmd neither present not trans_huge.

Which can confuse a concurrent rmap walk, as when removing migration
ptes, seen in the dumped trace.  Although that rmap walk has a 4k page
to insert, anon_vmas containing THPs are in no way segregated from
4k-page anon_vmas, so the 4k-intent mm_find_pmd() does need to cope with
that instant when a trans_huge pmd is temporarily absent.

I don't think we need strengthen the locking at the THP end: it's easily
handled with an ACCESS_ONCE() before testing both conditions.

And since mm_find_pmd() had only one caller who wanted a THP rather than
a pmd, let's slightly repurpose it to fail when it hits a THP or
non-present pmd, and open code split_huge_page_address() again.

Signed-off-by: Hugh Dickins <hughd@google.com>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Bob Liu <bob.liu@oracle.com>
Cc: Christoph Lameter <cl@gentwo.org>
Cc: Dave Jones <davej@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-06-23 16:47:44 -07:00
Hugh Dickins 5338a93722 mm: thp: fix DEBUG_PAGEALLOC oops in copy_page_rep() 
Trinity has for over a year been reporting a CONFIG_DEBUG_PAGEALLOC oops
in copy_page_rep() called from copy_user_huge_page() called from
do_huge_pmd_wp_page().

I believe this is a DEBUG_PAGEALLOC false positive, due to the source
page being split, and a tail page freed, while copy is in progress; and
not a problem without DEBUG_PAGEALLOC, since the pmd_same() check will
prevent a miscopy from being made visible.

Fix by adding get_user_huge_page() and put_user_huge_page(): reducing to
the usual get_page() and put_page() on head page in the usual config;
but get and put references to all of the tail pages when
DEBUG_PAGEALLOC.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-06-23 16:47:44 -07:00
Andrew Morton ae3a8c1c23 mm/huge_memory.c: complete conversion to pr_foo() 
It was using a mix of pr_foo() and printk(KERN_ERR ...).

Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-06-04 16:53:58 -07:00
Kirill A. Shutemov ff9e43eb4f thp: consolidate assert checks in __split_huge_page() 
It doesn't make sense to have two assert checks for each invariant: one
for printing and one for BUG().

Let's trigger BUG() if we print error message.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-06-04 16:53:57 -07:00
Ingo Molnar 2fe5de9ce7 Merge branch 'sched/urgent' into sched/core, to avoid conflicts 
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2014-05-07 13:15:46 +02:00
Kirill A. Shutemov b5a8cad376 thp: close race between split and zap huge pages 
Sasha Levin has reported two THP BUGs[1][2].  I believe both of them
have the same root cause.  Let's look to them one by one.

The first bug[1] is "kernel BUG at mm/huge_memory.c:1829!".  It's
BUG_ON(mapcount != page_mapcount(page)) in __split_huge_page().  From my
testing I see that page_mapcount() is higher than mapcount here.

I think it happens due to race between zap_huge_pmd() and
page_check_address_pmd().  page_check_address_pmd() misses PMD which is
under zap:

	CPU0						CPU1
						zap_huge_pmd()
						  pmdp_get_and_clear()
__split_huge_page()
  anon_vma_interval_tree_foreach()
    __split_huge_page_splitting()
      page_check_address_pmd()
        mm_find_pmd()
	  /*
	   * We check if PMD present without taking ptl: no
	   * serialization against zap_huge_pmd(). We miss this PMD,
	   * it's not accounted to 'mapcount' in __split_huge_page().
	   */
	  pmd_present(pmd) == 0

  BUG_ON(mapcount != page_mapcount(page)) // CRASH!!!

						  page_remove_rmap(page)
						    atomic_add_negative(-1, &page->_mapcount)

The second bug[2] is "kernel BUG at mm/huge_memory.c:1371!".
It's VM_BUG_ON_PAGE(!PageHead(page), page) in zap_huge_pmd().

This happens in similar way:

	CPU0						CPU1
						zap_huge_pmd()
						  pmdp_get_and_clear()
						  page_remove_rmap(page)
						    atomic_add_negative(-1, &page->_mapcount)
__split_huge_page()
  anon_vma_interval_tree_foreach()
    __split_huge_page_splitting()
      page_check_address_pmd()
        mm_find_pmd()
	  pmd_present(pmd) == 0	/* The same comment as above */
  /*
   * No crash this time since we already decremented page->_mapcount in
   * zap_huge_pmd().
   */
  BUG_ON(mapcount != page_mapcount(page))

  /*
   * We split the compound page here into small pages without
   * serialization against zap_huge_pmd()
   */
  __split_huge_page_refcount()
						VM_BUG_ON_PAGE(!PageHead(page), page); // CRASH!!!

So my understanding the problem is pmd_present() check in mm_find_pmd()
without taking page table lock.

The bug was introduced by me commit with commit 117b0791ac. Sorry for
that. :(

Let's open code mm_find_pmd() in page_check_address_pmd() and do the
check under page table lock.

Note that __page_check_address() does the same for PTE entires
if sync != 0.

I've stress tested split and zap code paths for 36+ hours by now and
don't see crashes with the patch applied. Before it took <20 min to
trigger the first bug and few hours for second one (if we ignore
first).

[1] https://lkml.kernel.org/g/<53440991.9090001@oracle.com>
[2] https://lkml.kernel.org/g/<5310C56C.60709@oracle.com>

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Bob Liu <lliubbo@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michel Lespinasse <walken@google.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>	[3.13+]

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-04-18 16:40:09 -07:00
Dongsheng Yang 8698a745d8 sched, treewide: Replace hardcoded nice values with MIN_NICE/MAX_NICE 
Replace various -20/+19 hardcoded nice values with MIN_NICE/MAX_NICE.

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/ff13819fd09b7a5dba5ab5ae797f2e7019bdfa17.1394532288.git.yangds.fnst@cn.fujitsu.com
Cc: devel@driverdev.osuosl.org
Cc: devicetree@vger.kernel.org
Cc: fcoe-devel@open-fcoe.org
Cc: linux390@de.ibm.com
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-s390@vger.kernel.org
Cc: linux-scsi@vger.kernel.org
Cc: nbd-general@lists.sourceforge.net
Cc: ocfs2-devel@oss.oracle.com
Cc: openipmi-developer@lists.sourceforge.net
Cc: qla2xxx-upstream@qlogic.com
Cc: linux-arch@vger.kernel.org
[ Consolidated the patches, twiddled the changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 2014-04-18 12:07:24 +02:00
Michal Hocko d715ae08f2 memcg: rename high level charging functions 
mem_cgroup_newpage_charge is used only for charging anonymous memory so
it is better to rename it to mem_cgroup_charge_anon.

mem_cgroup_cache_charge is used for file backed memory so rename it to
mem_cgroup_charge_file.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2014-04-07 16:35:57 -07:00