The 32-bit TCE table initialization relies on the DMA window having a
size equal to a power of 2 (and checks for it explicitly). But
crashkernel= has no constraint that requires a power-of-2 be specified.
This causes the kdump kernel to fail to boot as none of the PCI devices
(including the disk controller) are successfully initialized.
After this change, the PCI devices successfully set up the 32-bit TCE
table and kdump succeeds.
Fixes: aca6913f55 ("powerpc/powernv/ioda2: Introduce helpers to allocate TCE pages")
Signed-off-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org # 4.2
Tested-by: Jan Stancek <jstancek@redhat.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
When attempting to kdump with the 4.2 kernel, we see for each PCI
device:
pci 0003:01 : [PE# 000] Assign DMA32 space
pci 0003:01 : [PE# 000] Setting up 32-bit TCE table at 0..80000000
pci 0003:01 : [PE# 000] Failed to create 32-bit TCE table, err -22
PCI: Domain 0004 has 8 available 32-bit DMA segments
PCI: 4 PE# for a total weight of 70
pci 0004:01 : [PE# 002] Assign DMA32 space
pci 0004:01 : [PE# 002] Setting up 32-bit TCE table at 0..80000000
pci 0004:01 : [PE# 002] Failed to create 32-bit TCE table, err -22
pci 0004:0d : [PE# 005] Assign DMA32 space
pci 0004:0d : [PE# 005] Setting up 32-bit TCE table at 0..80000000
pci 0004:0d : [PE# 005] Failed to create 32-bit TCE table, err -22
pci 0004:0e : [PE# 006] Assign DMA32 space
pci 0004:0e : [PE# 006] Setting up 32-bit TCE table at 0..80000000
pci 0004:0e : [PE# 006] Failed to create 32-bit TCE table, err -22
pci 0004:10 : [PE# 008] Assign DMA32 space
pci 0004:10 : [PE# 008] Setting up 32-bit TCE table at 0..80000000
pci 0004:10 : [PE# 008] Failed to create 32-bit TCE table, err -22
and eventually the kdump kernel fails to boot as none of the PCI devices
(including the disk controller) are successfully initialized.
The EINVAL response is because the DMA window (the 2GB base window) is
larger than the kdump kernel's reserved memory (crashkernel=, in this
case specified to be 1024M). The check in question,
if ((window_size > memory_hotplug_max()) || !is_power_of_2(window_size))
is a valid sanity check for pnv_pci_ioda2_table_alloc_pages(), so adjust
the caller to pass in a smaller window size if our maximum memory value
is smaller than the DMA window.
After this change, the PCI devices successfully set up the 32-bit TCE
table and kdump succeeds.
The problem was seen on a Firestone machine originally.
Fixes: aca6913f55 ("powerpc/powernv/ioda2: Introduce helpers to allocate TCE pages")
Cc: stable@vger.kernel.org # 4.2
Signed-off-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
[mpe: Coding style pedantry, use u64, change the indentation]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Pull vfs updates from Al Viro:
"In this one:
- d_move fixes (Eric Biederman)
- UFS fixes (me; locking is mostly sane now, a bunch of bugs in error
handling ought to be fixed)
- switch of sb_writers to percpu rwsem (Oleg Nesterov)
- superblock scalability (Josef Bacik and Dave Chinner)
- swapon(2) race fix (Hugh Dickins)"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (65 commits)
vfs: Test for and handle paths that are unreachable from their mnt_root
dcache: Reduce the scope of i_lock in d_splice_alias
dcache: Handle escaped paths in prepend_path
mm: fix potential data race in SyS_swapon
inode: don't softlockup when evicting inodes
inode: rename i_wb_list to i_io_list
sync: serialise per-superblock sync operations
inode: convert inode_sb_list_lock to per-sb
inode: add hlist_fake to avoid the inode hash lock in evict
writeback: plug writeback at a high level
change sb_writers to use percpu_rw_semaphore
shift percpu_counter_destroy() into destroy_super_work()
percpu-rwsem: kill CONFIG_PERCPU_RWSEM
percpu-rwsem: introduce percpu_rwsem_release() and percpu_rwsem_acquire()
percpu-rwsem: introduce percpu_down_read_trylock()
document rwsem_release() in sb_wait_write()
fix the broken lockdep logic in __sb_start_write()
introduce __sb_writers_{acquired,release}() helpers
ufs_inode_get{frag,block}(): get rid of 'phys' argument
ufs_getfrag_block(): tidy up a bit
...
I've gotten several more over the past week, but this group has been
in for-next for at least a couple of weeks so I figured I'd push them
first while I test the rest. Most of the ones not in this set are
bug-fixes anyways so I could hold them for rc1 if you'd rather they
see more time in for-next.
-eric
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Merge tag 'for-linus-4.3-merge-window-part-1' of git://git.kernel.org/pub/scm/linux/kernel/git/ericvh/v9fs
Pull 9p updates from Eric Van Hensbergen:
"Just a few cleanups for 4.3 merge window for the 9p file system. I've
gotten several more over the past week, but this group has been in
for-next for at least a couple of weeks so I figured I'd push them
first while I test the rest.
Most of the ones not in this set are bug-fixes anyways so I could hold
them for rc1"
* tag 'for-linus-4.3-merge-window-part-1' of git://git.kernel.org/pub/scm/linux/kernel/git/ericvh/v9fs:
9p: fix return code of read() when count is 0
9p: remove unused option Opt_trans
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Merge tag 'media/v4.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media
Pull media updates from Mauro Carvalho Chehab:
- new DVB frontend drivers: ascot2e, cxd2841er, horus3a, lnbh25
- new HDMI capture driver: tc358743
- new driver for NetUP DVB new boards (netup_unidvb)
- IR support for DVBSky cards (smipcie-ir)
- Coda driver has gain macroblock tiling support
- Renesas R-Car gains JPEG codec driver
- new DVB platform driver for STi boards: c8sectpfe
- added documentation for the media core kABI to device-drivers DocBook
- lots of driver fixups, cleanups and improvements
* tag 'media/v4.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (297 commits)
[media] c8sectpfe: Remove select on undefined LIBELF_32
[media] i2c: fix platform_no_drv_owner.cocci warnings
[media] cx231xx: Use wake_up_interruptible() instead of wake_up_interruptible_nr()
[media] tc358743: only queue subdev notifications if devnode is set
[media] tc358743: add missing Kconfig dependency/select
[media] c8sectpfe: Use %pad to print 'dma_addr_t'
[media] DocBook media: Fix typo "the the" in xml files
[media] tc358743: make reset gpio optional
[media] tc358743: set direction of reset gpio using devm_gpiod_get
[media] dvbdev: document most of the functions/data structs
[media] dvb_frontend.h: document the struct dvb_frontend
[media] dvb-frontend.h: document struct dtv_frontend_properties
[media] dvb-frontend.h: document struct dvb_frontend_ops
[media] dvb: Use DVBFE_ALGO_HW where applicable
[media] dvb_frontend.h: document struct analog_demod_ops
[media] dvb_frontend.h: Document struct dvb_tuner_ops
[media] Docbook: Document struct analog_parameters
[media] dvb_frontend.h: get rid of dvbfe_modcod
[media] add documentation for struct dvb_tuner_info
[media] dvb_frontend: document dvb_frontend_tune_settings
...
Pull mailbox updates from Jassi Brar:
"Mainly we move from jiffy based timer to HRTIMER for finer control
over polling. Then a controller reduces its polling period from 10 to
1ms"
* 'mailbox-for-next' of git://git.linaro.org/landing-teams/working/fujitsu/integration:
mailbox: arm_mhu: reduce txpoll_period from 10ms to 1 ms
mailbox: switch to hrtimer for tx_complete polling
mailbox: Drop owner assignment from platform_driver
- An assortment of little fixes, several for minor races only likely
to be hit during testing
- further cluster-md-raid1 development, not ready for real use yet.
- new RAID6 syndrome code for ARM NEON
- fix a race where a write can return before failure of one device
is properly recorded in metadata, so an immediate crash might result
in that write being lost.
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Merge tag 'md/4.3' of git://neil.brown.name/md
Pull md updates from Neil Brown:
- an assortment of little fixes, several for minor races only likely to
be hit during testing
- further cluster-md-raid1 development, not ready for real use yet.
- new RAID6 syndrome code for ARM NEON
- fix a race where a write can return before failure of one device is
properly recorded in metadata, so an immediate crash might result in
that write being lost.
* tag 'md/4.3' of git://neil.brown.name/md: (33 commits)
md/raid5: ensure device failure recorded before write request returns.
md/raid5: use bio_list for the list of bios to return.
md/raid10: ensure device failure recorded before write request returns.
md/raid1: ensure device failure recorded before write request returns.
md-cluster: remove inappropriate try_module_get from join()
md: extend spinlock protection in register_md_cluster_operations
md-cluster: Read the disk bitmap sb and check if it needs recovery
md-cluster: only call complete(&cinfo->completion) when node join cluster
md-cluster: add missed lockres_free
md-cluster: remove the unused sb_lock
md-cluster: init suspend_list and suspend_lock early in join
md-cluster: add the error check if failed to get dlm lock
md-cluster: init completion within lockres_init
md-cluster: fix deadlock issue on message lock
md-cluster: transfer the resync ownership to another node
md-cluster: split recover_slot for future code reuse
md-cluster: use %pU to print UUIDs
md: setup safemode_timer before it's being used
md/raid5: handle possible race as reshape completes.
md: sync sync_completed has correct value as recovery finishes.
...
- Add Jeff Layton as an nfsd co-maintainer: no change to
existing practice, just an acknowledgement of the status quo.
- Two patches ("nfsd: ensure that...") for a race overlooked by
the state locking rewrite, causing a crash noticed by multiple
users.
- Lots of smaller bugfixes all over from Kinglong Mee.
- From Jeff, some cleanup of server rpc code in preparation for
possible shift of nfsd threads to workqueues.
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Merge tag 'nfsd-4.3' of git://linux-nfs.org/~bfields/linux
Pull nfsd updates from Bruce Fields:
"Nothing major, but:
- Add Jeff Layton as an nfsd co-maintainer: no change to existing
practice, just an acknowledgement of the status quo.
- Two patches ("nfsd: ensure that...") for a race overlooked by the
state locking rewrite, causing a crash noticed by multiple users.
- Lots of smaller bugfixes all over from Kinglong Mee.
- From Jeff, some cleanup of server rpc code in preparation for
possible shift of nfsd threads to workqueues"
* tag 'nfsd-4.3' of git://linux-nfs.org/~bfields/linux: (52 commits)
nfsd: deal with DELEGRETURN racing with CB_RECALL
nfsd: return CLID_INUSE for unexpected SETCLIENTID_CONFIRM case
nfsd: ensure that delegation stateid hash references are only put once
nfsd: ensure that the ol stateid hash reference is only put once
net: sunrpc: fix tracepoint Warning: unknown op '->'
nfsd: allow more than one laundry job to run at a time
nfsd: don't WARN/backtrace for invalid container deployment.
fs: fix fs/locks.c kernel-doc warning
nfsd: Add Jeff Layton as co-maintainer
NFSD: Return word2 bitmask if setting security label in OPEN/CREATE
NFSD: Set the attributes used to store the verifier for EXCLUSIVE4_1
nfsd: SUPPATTR_EXCLCREAT must be encoded before SECURITY_LABEL.
nfsd: Fix an FS_LAYOUT_TYPES/LAYOUT_TYPES encode bug
NFSD: Store parent's stat in a separate value
nfsd: Fix two typos in comments
lockd: NLM grace period shouldn't block NFSv4 opens
nfsd: include linux/nfs4.h in export.h
sunrpc: Switch to using hash list instead single list
sunrpc/nfsd: Remove redundant code by exports seq_operations functions
sunrpc: Store cache_detail in seq_file's private directly
...
Pull btrfs updates from Chris Mason:
"This has Jeff Mahoney's long standing trim patch that fixes corners
where trims were missing. Omar has some raid5/6 fixes, especially for
using scrub and device replace when devices are missing.
Zhao Lie continues cleaning and fixing things, this series fixes some
really hard to hit corners in xfstests. I had to pull it last merge
window due to some deadlocks, but those are now resolved.
I added support for Tejun's new blkio controllers. It seems to work
well for single devices, we'll expand to multi-device as well"
* 'for-linus-4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: (47 commits)
btrfs: fix compile when block cgroups are not enabled
Btrfs: fix file read corruption after extent cloning and fsync
Btrfs: check if previous transaction aborted to avoid fs corruption
btrfs: use __GFP_NOFAIL in alloc_btrfs_bio
btrfs: Prevent from early transaction abort
btrfs: Remove unused arguments in tree-log.c
btrfs: Remove useless condition in start_log_trans()
Btrfs: add support for blkio controllers
Btrfs: remove unused mutex from struct 'btrfs_fs_info'
Btrfs: fix parity scrub of RAID 5/6 with missing device
Btrfs: fix device replace of a missing RAID 5/6 device
Btrfs: add RAID 5/6 BTRFS_RBIO_REBUILD_MISSING operation
Btrfs: count devices correctly in readahead during RAID 5/6 replace
Btrfs: remove misleading handling of missing device scrub
btrfs: fix clone / extent-same deadlocks
Btrfs: fix defrag to merge tail file extent
Btrfs: fix warning in backref walking
btrfs: Add WARN_ON() for double lock in btrfs_tree_lock()
btrfs: Remove root argument in extent_data_ref_count()
btrfs: Fix wrong comment of btrfs_alloc_tree_block()
...
Merge patch-bomb from Andrew Morton:
- a few misc things
- Andy's "ambient capabilities"
- fs/nofity updates
- the ocfs2 queue
- kernel/watchdog.c updates and feature work.
- some of MM. Includes Andrea's userfaultfd feature.
[ Hadn't noticed that userfaultfd was 'default y' when applying the
patches, so that got fixed in this merge instead. We do _not_ mark
new features that nobody uses yet 'default y' - Linus ]
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (118 commits)
mm/hugetlb.c: make vma_has_reserves() return bool
mm/madvise.c: make madvise_behaviour_valid() return bool
mm/memory.c: make tlb_next_batch() return bool
mm/dmapool.c: change is_page_busy() return from int to bool
mm: remove struct node_active_region
mremap: simplify the "overlap" check in mremap_to()
mremap: don't do uneccesary checks if new_len == old_len
mremap: don't do mm_populate(new_addr) on failure
mm: move ->mremap() from file_operations to vm_operations_struct
mremap: don't leak new_vma if f_op->mremap() fails
mm/hugetlb.c: make vma_shareable() return bool
mm: make GUP handle pfn mapping unless FOLL_GET is requested
mm: fix status code which move_pages() returns for zero page
mm: memcontrol: bring back the VM_BUG_ON() in mem_cgroup_swapout()
genalloc: add support of multiple gen_pools per device
genalloc: add name arg to gen_pool_get() and devm_gen_pool_create()
mm/memblock: WARN_ON when nid differs from overlap region
Documentation/features/vm: add feature description and arch support status for batched TLB flush after unmap
mm: defer flush of writable TLB entries
mm: send one IPI per CPU to TLB flush all entries after unmapping pages
...
In commit f341861fb0 ("task_work: add a scheduling point in
task_work_run()") I fixed a latency problem adding a cond_resched()
call.
Later, commit ac3d0da8f3 added yet another loop to reverse a list,
bringing back the latency spike :
I've seen in some cases this loop taking 275 ms, if for example a
process with 2,000,000 files is killed.
We could add yet another cond_resched() in the reverse loop, or we
can simply remove the reversal, as I do not think anything
would depend on order of task_work_add() submitted works.
Fixes: ac3d0da8f3 ("task_work: Make task_work_add() lockless")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Maciej Żenczykowski <maze@google.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This makes vma_has_reserves() return bool due to this particular function
only returning either one or zero as its return value.
Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This makes the madvise_bahaviour_valid() function return bool due to
this particular function always returning the value of either one or
zero as its return value.
Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This makes the tlb_next_batch() bool due to this particular function only
ever returning either one or zero as its return value.
Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This makes the function is_page_busy() return bool rather then an int now
due to this particular function's single return statement only ever
evaulating to either one or zero.
Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
struct node_active_region is not used anymore. Remove it.
Signed-off-by: minkyung88.kim <minkyung88.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Minor, but this check is overcomplicated. Two half-intervals do NOT
overlap if END1 <= START2 || END2 <= START1, mremap_to() just needs to
negate this check.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The "new_len > old_len" branch in vma_to_resize() looks very confusing.
It only covers the VM_DONTEXPAND/pgoff checks but everything below is
equally unneeded if new_len == old_len.
Change this code to return if "new_len == old_len", new_len < old_len is
not possible, otherwise the code below is wrong anyway.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
move_vma() sets *locked even if move_page_tables() or ->mremap() fails,
change sys_mremap() to check "ret & ~PAGE_MASK".
I think we should simply remove the VM_LOCKED code in move_vma(), that is
why this patch doesn't change move_vma(). But this needs more cleanups.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
vma->vm_ops->mremap() looks more natural and clean in move_vma(), and this
way ->mremap() can have more users. Say, vdso.
While at it, s/aio_ring_remap/aio_ring_mremap/.
Note: this is the minimal change before ->mremap() finds another user in
file_operations; this method should have more arguments, and it can be
used to kill arch_remap().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
move_vma() can't just return if f_op->mremap() fails, we should unmap the
new vma like we do if move_page_tables() fails. To avoid the code
duplication this patch moves the "move entries back" under the new "if
(err)" branch.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This makes vma_shareable() return bool now due to this particular function
only ever returning either one or zero as its return value.
Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
Acked-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.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>
With DAX, pfn mapping becoming more common. The patch adjusts GUP code to
cover pfn mapping for cases when we don't need struct page to proceed.
To make it possible, let's change follow_page() code to return -EEXIST
error code if proper page table entry exists, but no corresponding struct
page. __get_user_page() would ignore the error code and move to the next
page frame.
The immediate effect of the change is working MAP_POPULATE and mlock() on
DAX mappings.
[akpm@linux-foundation.org: fix arm64 build]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Toshi Kani <toshi.kani@hp.com>
Acked-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>
The manpage for move_pages(2) specifies that status code for zero page is
supposed to be -EFAULT. Currently kernel return -ENOENT in this case.
follow_page() can do it for us, if we would ask for FOLL_DUMP. The use of
FOLL_DUMP also means that the upper layer page tables pages are no longer
allocated.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Christoph Lameter <cl@linux.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Clark stumbled over a VM_BUG_ON() in -RT which was then was removed by
Johannes in commit f371763a79 ("mm: memcontrol: fix false-positive
VM_BUG_ON() on -rt"). The comment before that patch was a tiny bit better
than it is now. While the patch claimed to fix a false-postive on -RT
this was not the case. None of the -RT folks ACKed it and it was not a
false positive report. That was a *real* problem.
This patch updates the comment that is improper because it refers to
"disabled preemption" as a consequence of that lock being taken. A
spin_lock() disables preemption, true, but in this case the code relies on
the fact that the lock _also_ disables interrupts once it is acquired.
And this is the important detail (which was checked the VM_BUG_ON()) which
needs to be pointed out. This is the hint one needs while looking at the
code. It was explained by Johannes on the list that the per-CPU variables
are protected by local_irq_save(). The BUG_ON() was helpful. This code
has been workarounded in -RT in the meantime. I wouldn't mind running
into more of those if the code in question uses *special* kind of locking
since now there is no verification (in terms of lockdep or BUG_ON()) and
therefore I bring the VM_BUG_ON() check back in.
The two functions after the comment could also have a "local_irq_save()"
dance around them in order to serialize access to the per-CPU variables.
This has been avoided because the interrupts should be off.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Clark Williams <williams@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This change fills devm_gen_pool_create()/gen_pool_get() "name" argument
stub with contents and extends of_gen_pool_get() functionality on this
basis.
If there is no associated platform device with a device node passed to
of_gen_pool_get(), the function attempts to get a label property or device
node name (= repeats MTD OF partition standard) and seeks for a named
gen_pool registered by device of the parent device node.
The main idea of the change is to allow registration of independent
gen_pools under the same umbrella device, say "partitions" on "storage
device", the original functionality of one "partition" per "storage
device" is untouched.
[akpm@linux-foundation.org: fix constness in devres_find()]
[dan.carpenter@oracle.com: freeing const data pointers]
Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Cc: Arnd Bergmann <arnd@arndb.de>
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>
This change modifies gen_pool_get() and devm_gen_pool_create() client
interfaces adding one more argument "name" of a gen_pool object.
Due to implementation gen_pool_get() is capable to retrieve only one
gen_pool associated with a device even if multiple gen_pools are created,
fortunately right at the moment it is sufficient for the clients, hence
provide NULL as a valid argument on both producer devm_gen_pool_create()
and consumer gen_pool_get() sides.
Because only one created gen_pool per device is addressable, explicitly
add a restriction to devm_gen_pool_create() to create only one gen_pool
per device, this implies two possible error codes returned by the
function, account it on client side (only misc/sram). This completes
client side changes related to genalloc updates.
[akpm@linux-foundation.org: gen_pool_get() cleanup]
Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Each memblock_region has nid to indicates the Node ID of this range. For
the overlap case, memblock_add_range() inserts the lower part and leave
the upper part as indicated in the overlapped region.
If the nid of the new range differs from the overlapped region, the
information recorded is not correct.
This patch adds a WARN_ON when the nid of the new range differs from the
overlapped region.
Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com>
Acked-by: David Rientjes <rientjes@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>
If a PTE is unmapped and it's dirty then it was writable recently. Due to
deferred TLB flushing, it's best to assume a writable TLB cache entry
exists. With that assumption, the TLB must be flushed before any IO can
start or the page is freed to avoid lost writes or data corruption. This
patch defers flushing of potentially writable TLBs as long as possible.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
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>
An IPI is sent to flush remote TLBs when a page is unmapped that was
potentially accesssed by other CPUs. There are many circumstances where
this happens but the obvious one is kswapd reclaiming pages belonging to a
running process as kswapd and the task are likely running on separate
CPUs.
On small machines, this is not a significant problem but as machine gets
larger with more cores and more memory, the cost of these IPIs can be
high. This patch uses a simple structure that tracks CPUs that
potentially have TLB entries for pages being unmapped. When the unmapping
is complete, the full TLB is flushed on the assumption that a refill cost
is lower than flushing individual entries.
Architectures wishing to do this must give the following guarantee.
If a clean page is unmapped and not immediately flushed, the
architecture must guarantee that a write to that linear address
from a CPU with a cached TLB entry will trap a page fault.
This is essentially what the kernel already depends on but the window is
much larger with this patch applied and is worth highlighting. The
architecture should consider whether the cost of the full TLB flush is
higher than sending an IPI to flush each individual entry. An additional
architecture helper called flush_tlb_local is required. It's a trivial
wrapper with some accounting in the x86 case.
The impact of this patch depends on the workload as measuring any benefit
requires both mapped pages co-located on the LRU and memory pressure. The
case with the biggest impact is multiple processes reading mapped pages
taken from the vm-scalability test suite. The test case uses NR_CPU
readers of mapped files that consume 10*RAM.
Linear mapped reader on a 4-node machine with 64G RAM and 48 CPUs
4.2.0-rc1 4.2.0-rc1
vanilla flushfull-v7
Ops lru-file-mmap-read-elapsed 159.62 ( 0.00%) 120.68 ( 24.40%)
Ops lru-file-mmap-read-time_range 30.59 ( 0.00%) 2.80 ( 90.85%)
Ops lru-file-mmap-read-time_stddv 6.70 ( 0.00%) 0.64 ( 90.38%)
4.2.0-rc1 4.2.0-rc1
vanilla flushfull-v7
User 581.00 611.43
System 5804.93 4111.76
Elapsed 161.03 122.12
This is showing that the readers completed 24.40% faster with 29% less
system CPU time. From vmstats, it is known that the vanilla kernel was
interrupted roughly 900K times per second during the steady phase of the
test and the patched kernel was interrupts 180K times per second.
The impact is lower on a single socket machine.
4.2.0-rc1 4.2.0-rc1
vanilla flushfull-v7
Ops lru-file-mmap-read-elapsed 25.33 ( 0.00%) 20.38 ( 19.54%)
Ops lru-file-mmap-read-time_range 0.91 ( 0.00%) 1.44 (-58.24%)
Ops lru-file-mmap-read-time_stddv 0.28 ( 0.00%) 0.47 (-65.34%)
4.2.0-rc1 4.2.0-rc1
vanilla flushfull-v7
User 58.09 57.64
System 111.82 76.56
Elapsed 27.29 22.55
It's still a noticeable improvement with vmstat showing interrupts went
from roughly 500K per second to 45K per second.
The patch will have no impact on workloads with no memory pressure or have
relatively few mapped pages. It will have an unpredictable impact on the
workload running on the CPU being flushed as it'll depend on how many TLB
entries need to be refilled and how long that takes. Worst case, the TLB
will be completely cleared of active entries when the target PFNs were not
resident at all.
[sasha.levin@oracle.com: trace tlb flush after disabling preemption in try_to_unmap_flush]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When unmapping pages it is necessary to flush the TLB. If that page was
accessed by another CPU then an IPI is used to flush the remote CPU. That
is a lot of IPIs if kswapd is scanning and unmapping >100K pages per
second.
There already is a window between when a page is unmapped and when it is
TLB flushed. This series increases the window so multiple pages can be
flushed using a single IPI. This should be safe or the kernel is hosed
already.
Patch 1 simply made the rest of the series easier to write as ftrace
could identify all the senders of TLB flush IPIS.
Patch 2 tracks what CPUs potentially map a PFN and then sends an IPI
to flush the entire TLB.
Patch 3 tracks when there potentially are writable TLB entries that
need to be batched differently
Patch 4 increases SWAP_CLUSTER_MAX to further batch flushes
The performance impact is documented in the changelogs but in the optimistic
case on a 4-socket machine the full series reduces interrupts from 900K
interrupts/second to 60K interrupts/second.
This patch (of 4):
It is easy to trace when an IPI is received to flush a TLB but harder to
detect what event sent it. This patch makes it easy to identify the
source of IPIs being transmitted for TLB flushes on x86.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
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>
This test allocates two virtual areas and bounces the physical memory
across the two virtual areas using only userfaultfd.
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>
Cc: Shuah Khan <shuah.kh@samsung.com>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
During the refile in userfaultfd_read both waitqueues could look empty to
the lockless wake_userfault(). Use a seqcount to prevent this false
negative that could leave an userfault blocked.
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>
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>
This is only simple to achieve if the userfault is going to return to
userland (not to the kernel) because we can avoid returning VM_FAULT_RETRY
despite we temporarily released the mmap_sem. The fault would just be
retried by userland then. This is safe at least on x86 and powerpc (the
two archs with the syscall implemented so far).
Hint to verify for which archs this is safe: after handle_mm_fault
returns, no access to data structures protected by the mmap_sem must be
done by the fault code in arch/*/mm/fault.c until up_read(&mm->mmap_sem)
is called.
This has two main benefits: signals can run with lower latency in
production (signals aren't blocked by userfaults and userfaults are
immediately repeated after signal processing) and gdb can then trivially
debug the threads blocked in this kind of userfaults coming directly from
userland.
On a side note: while gdb has a need to get signal processed, coredumps
always worked perfectly with userfaults, no matter if the userfault is
triggered by GUP a kernel copy_user or directly from userland.
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>
UFFDIO_API was already forced before read/poll could work. This makes the
code more strict to force it also for all other ioctls.
All users would already have been required to call UFFDIO_API before
invoking other ioctls but this makes it more explicit.
This will ensure we can change all ioctls (all but UFFDIO_API/struct
uffdio_api) with a bump of uffdio_api.api.
There's no actual plan or need to change the API or the ioctl, the current
API already should cover fine even the non cooperative usage, but this is
just for the longer term future just in case.
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>
These two ioctl allows to either atomically copy or to map zeropages
into the virtual address space. This is used by the thread that opened
the userfaultfd to resolve the userfaults.
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>
If the rwsem starves writers it wasn't strictly a bug but lockdep
doesn't like it and this avoids depending on lowlevel implementation
details of the lock.
[akpm@linux-foundation.org: delete weird BUILD_BUG_ON()]
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>
This implements mcopy_atomic and mfill_zeropage that are the lowlevel
VM methods that are invoked respectively by the UFFDIO_COPY and
UFFDIO_ZEROPAGE userfaultfd commands.
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>
This implements the uABI of UFFDIO_COPY and UFFDIO_ZEROPAGE.
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>
This allows to select the userfaultfd during configuration to build it.
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>
Solve in-kernel the race between UFFDIO_COPY|ZEROPAGE and
userfaultfd_read if they are run on different threads simultaneously.
Until now qemu solved the race in userland: the race was explicitly
and intentionally left for userland to solve. However we can also
solve it in kernel.
Requiring all users to solve this race if they use two threads (one
for the background transfer and one for the userfault reads) isn't
very attractive from an API prospective, furthermore this allows to
remove a whole bunch of mutex and bitmap code from qemu, making it
faster. The cost of __get_user_pages_fast should be insignificant
considering it scales perfectly and the pagetables are already hot in
the CPU cache, compared to the overhead in userland to maintain those
structures.
Applying this patch is backwards compatible with respect to the
userfaultfd userland API, however reverting this change wouldn't be
backwards compatible anymore.
Without this patch qemu in the background transfer thread, has to read
the old state, and do UFFDIO_WAKE if old_state is missing but it
become REQUESTED by the time it tries to set it to RECEIVED (signaling
the other side received an userfault).
vcpu background_thr userfault_thr
----- ----- -----
vcpu0 handle_mm_fault()
postcopy_place_page
read old_state -> MISSING
UFFDIO_COPY 0x7fb76a139000 (no wakeup, still pending)
vcpu0 fault at 0x7fb76a139000 enters handle_userfault
poll() is kicked
poll() -> POLLIN
read() -> 0x7fb76a139000
postcopy_pmi_change_state(MISSING, REQUESTED) -> REQUESTED
tmp_state = postcopy_pmi_change_state(old_state, RECEIVED) -> REQUESTED
/* check that no userfault raced with UFFDIO_COPY */
if (old_state == MISSING && tmp_state == REQUESTED)
UFFDIO_WAKE from background thread
And a second case where a UFFDIO_WAKE would be needed is in the userfault thread:
vcpu background_thr userfault_thr
----- ----- -----
vcpu0 handle_mm_fault()
postcopy_place_page
read old_state -> MISSING
UFFDIO_COPY 0x7fb76a139000 (no wakeup, still pending)
tmp_state = postcopy_pmi_change_state(old_state, RECEIVED) -> RECEIVED
vcpu0 fault at 0x7fb76a139000 enters handle_userfault
poll() is kicked
poll() -> POLLIN
read() -> 0x7fb76a139000
if (postcopy_pmi_change_state(MISSING, REQUESTED) == RECEIVED)
UFFDIO_WAKE from userfault thread
This patch removes the need of both UFFDIO_WAKE and of the associated
per-page tristate as well.
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>
This makes read O(1) and poll that was already O(1) becomes lockless.
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>
This is an optimization but it's a userland visible one and it affects
the API.
The downside of this optimization is that if you call poll() and you
get POLLIN, read(ufd) may still return -EAGAIN. The blocked userfault
may be waken by a different thread, before read(ufd) comes
around. This in short means that poll() isn't really usable if the
userfaultfd is opened in blocking mode.
userfaults won't wait in "pending" state to be read anymore and any
UFFDIO_WAKE or similar operations that has the objective of waking
userfaults after their resolution, will wake all blocked userfaults
for the resolved range, including those that haven't been read() by
userland yet.
The behavior of poll() becomes not standard, but this obviates the
need of "spurious" UFFDIO_WAKE and it lets the userland threads to
restart immediately without requiring an UFFDIO_WAKE. This is even
more significant in case of repeated faults on the same address from
multiple threads.
This optimization is justified by the measurement that the number of
spurious UFFDIO_WAKE accounts for 5% and 10% of the total
userfaults for heavy workloads, so it's worth optimizing those away.
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>
I had requests to return the full address (not the page aligned one) to
userland.
It's not entirely clear how the page offset could be relevant because
userfaults aren't like SIGBUS that can sigjump to a different place and it
actually skip resolving the fault depending on a page offset. There's
currently no real way to skip the fault especially because after a
UFFDIO_COPY|ZEROPAGE, the fault is optimized to be retried within the
kernel without having to return to userland first (not even self modifying
code replacing the .text that touched the faulting address would prevent
the fault to be repeated). Userland cannot skip repeating the fault even
more so if the fault was triggered by a KVM secondary page fault or any
get_user_pages or any copy-user inside some syscall which will return to
kernel code. The second time FAULT_FLAG_RETRY_NOWAIT won't be set leading
to a SIGBUS being raised because the userfault can't wait if it cannot
release the mmap_map first (and FAULT_FLAG_RETRY_NOWAIT is required for
that).
Still returning userland a proper structure during the read() on the uffd,
can allow to use the current UFFD_API for the future non-cooperative
extensions too and it looks cleaner as well. Once we get additional
fields there's no point to return the fault address page aligned anymore
to reuse the bits below PAGE_SHIFT.
The only downside is that the read() syscall will read 32bytes instead of
8bytes but that's not going to be measurable overhead.
The total number of new events that can be extended or of new future bits
for already shipped events, is limited to 64 by the features field of the
uffdio_api structure. If more will be needed a bump of UFFD_API will be
required.
[akpm@linux-foundation.org: use __packed]
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>
This is (seems to be) the minimal thing that is required to unblock
standard uffd usage from the non-cooperative one. Now more bits can be
added to the features field indicating e.g. UFFD_FEATURE_FORK and others
needed for the latter use-case.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.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>
Nishanth Aravamudan