mirror of https://gitee.com/openkylin/linux.git
152 Commits
| Author | SHA1 | Message | Date |
|---|---|---|---|
Jia He
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1105a2fc02 |
mm/ksm.c: ignore STABLE_FLAG of rmap_item->address in rmap_walk_ksm()
In our armv8a server(QDF2400), I noticed lots of WARN_ON caused by PAGE_SIZE unaligned for rmap_item->address under memory pressure tests(start 20 guests and run memhog in the host). WARNING: CPU: 4 PID: 4641 at virt/kvm/arm/mmu.c:1826 kvm_age_hva_handler+0xc0/0xc8 CPU: 4 PID: 4641 Comm: memhog Tainted: G W 4.17.0-rc3+ #8 Call trace: kvm_age_hva_handler+0xc0/0xc8 handle_hva_to_gpa+0xa8/0xe0 kvm_age_hva+0x4c/0xe8 kvm_mmu_notifier_clear_flush_young+0x54/0x98 __mmu_notifier_clear_flush_young+0x6c/0xa0 page_referenced_one+0x154/0x1d8 rmap_walk_ksm+0x12c/0x1d0 rmap_walk+0x94/0xa0 page_referenced+0x194/0x1b0 shrink_page_list+0x674/0xc28 shrink_inactive_list+0x26c/0x5b8 shrink_node_memcg+0x35c/0x620 shrink_node+0x100/0x430 do_try_to_free_pages+0xe0/0x3a8 try_to_free_pages+0xe4/0x230 __alloc_pages_nodemask+0x564/0xdc0 alloc_pages_vma+0x90/0x228 do_anonymous_page+0xc8/0x4d0 __handle_mm_fault+0x4a0/0x508 handle_mm_fault+0xf8/0x1b0 do_page_fault+0x218/0x4b8 do_translation_fault+0x90/0xa0 do_mem_abort+0x68/0xf0 el0_da+0x24/0x28 In rmap_walk_ksm, the rmap_item->address might still have the STABLE_FLAG, then the start and end in handle_hva_to_gpa might not be PAGE_SIZE aligned. Thus it will cause exceptions in handle_hva_to_gpa on arm64. This patch fixes it by ignoring (not removing) the low bits of address when doing rmap_walk_ksm. IMO, it should be backported to stable tree. the storm of WARN_ONs is very easy for me to reproduce. More than that, I watched a panic (not reproducible) as follows: page:ffff7fe003742d80 count:-4871 mapcount:-2126053375 mapping: (null) index:0x0 flags: 0x1fffc00000000000() raw: 1fffc00000000000 0000000000000000 0000000000000000 ffffecf981470000 raw: dead000000000100 dead000000000200 ffff8017c001c000 0000000000000000 page dumped because: nonzero _refcount CPU: 29 PID: 18323 Comm: qemu-kvm Tainted: G W 4.14.15-5.hxt.aarch64 #1 Hardware name: <snip for confidential issues> Call trace: dump_backtrace+0x0/0x22c show_stack+0x24/0x2c dump_stack+0x8c/0xb0 bad_page+0xf4/0x154 free_pages_check_bad+0x90/0x9c free_pcppages_bulk+0x464/0x518 free_hot_cold_page+0x22c/0x300 __put_page+0x54/0x60 unmap_stage2_range+0x170/0x2b4 kvm_unmap_hva_handler+0x30/0x40 handle_hva_to_gpa+0xb0/0xec kvm_unmap_hva_range+0x5c/0xd0 I even injected a fault on purpose in kvm_unmap_hva_range by seting size=size-0x200, the call trace is similar as above. So I thought the panic is similarly caused by the root cause of WARN_ON. Andrea said: : It looks a straightforward safe fix, on x86 hva_to_gfn_memslot would : zap those bits and hide the misalignment caused by the low metadata : bits being erroneously left set in the address, but the arm code : notices when that's the last page in the memslot and the hva_end is : getting aligned and the size is below one page. : : I think the problem triggers in the addr += PAGE_SIZE of : unmap_stage2_ptes that never matches end because end is aligned but : addr is not. : : } while (pte++, addr += PAGE_SIZE, addr != end); : : x86 again only works on hva_start/hva_end after converting it to : gfn_start/end and that being in pfn units the bits are zapped before : they risk to cause trouble. Jia He said: : I've tested by myself in arm64 server (QDF2400,46 cpus,96G mem) Without : this patch, the WARN_ON is very easy for reproducing. After this patch, I : have run the same benchmarch for a whole day without any WARN_ONs Link: http://lkml.kernel.org/r/1525403506-6750-1-git-send-email-hejianet@gmail.com Signed-off-by: Jia He <jia.he@hxt-semitech.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Tested-by: Jia He <hejianet@gmail.com> Cc: Suzuki K Poulose <Suzuki.Poulose@arm.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com> Cc: Arvind Yadav <arvind.yadav.cs@gmail.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mike Rapoport
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88484826bc |
mm/ksm: move [set_]page_stable_node from ksm.h to ksm.c
page_stable_node() and set_page_stable_node() are only used in mm/ksm.c and there is no point to keep them in the include/linux/ksm.h [akpm@linux-foundation.org: fix SYSFS=n build] Link: http://lkml.kernel.org/r/1524552106-7356-3-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mike Rapoport
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5a2ca3efe6 |
mm/ksm: docs: extend overview comment and make it "DOC:"
The existing comment provides a good overview of KSM implementation. Let's update it to reflect recent additions of "chain" and "dup" variants of the stable tree nodes and mark it as "DOC:" for inclusion into the KSM documentation. Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net> |
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Jonathan Corbet
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24844fd339 |
Merge branch 'mm-rst' into docs-next
Mike Rapoport says: These patches convert files in Documentation/vm to ReST format, add an initial index and link it to the top level documentation. There are no contents changes in the documentation, except few spelling fixes. The relatively large diffstat stems from the indentation and paragraph wrapping changes. I've tried to keep the formatting as consistent as possible, but I could miss some places that needed markup and add some markup where it was not necessary. [jc: significant conflicts in vm/hmm.rst] |
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Mike Rapoport
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ad56b738c5 |
docs/vm: rename documentation files to .rst
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net> |
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Claudio Imbrenda
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a38c015f31 |
mm/ksm.c: fix inconsistent accounting of zero pages
When using KSM with use_zero_pages, we replace anonymous pages
containing only zeroes with actual zero pages, which are not anonymous.
We need to do proper accounting of the mm counters, otherwise we will
get wrong values in /proc and a BUG message in dmesg when tearing down
the mm.
Link: http://lkml.kernel.org/r/1522931274-15552-1-git-send-email-imbrenda@linux.vnet.ibm.com
Fixes:
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Claudio Imbrenda
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77da2ba064 |
mm/ksm: fix interaction with THP
This patch fixes a corner case for KSM. When two pages belong or belonged to the same transparent hugepage, and they should be merged, KSM fails to split the page, and therefore no merging happens. This bug can be reproduced by: * making sure ksm is running (in case disabling ksmtuned) * enabling transparent hugepages * allocating a THP-aligned 1-THP-sized buffer e.g. on amd64: posix_memalign(&p, 1<<21, 1<<21) * filling it with the same values e.g. memset(p, 42, 1<<21) * performing madvise to make it mergeable e.g. madvise(p, 1<<21, MADV_MERGEABLE) * waiting for KSM to perform a few scans The expected outcome is that the all the pages get merged (1 shared and the rest sharing); the actual outcome is that no pages get merged (1 unshared and the rest volatile) The reason of this behaviour is that we increase the reference count once for both pages we want to merge, but if they belong to the same hugepage (or compound page), the reference counter used in both cases is the one of the head of the compound page. This means that split_huge_page will find a value of the reference counter too high and will fail. This patch solves this problem by testing if the two pages to merge belong to the same hugepage when attempting to merge them. If so, the hugepage is split safely. This means that the hugepage is not split if not necessary. Link: http://lkml.kernel.org/r/1521548069-24758-1-git-send-email-imbrenda@linux.vnet.ibm.com Signed-off-by: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com> Co-authored-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Colin Ian King
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c01f0b54ef |
mm/ksm.c: make stable_node_dup() static
stable_node_dup() is local to the source and does not need to be in global scope, so make it static. Cleans up sparse warning: mm/ksm.c:1321:13: warning: symbol 'stable_node_dup' was not declared. Should it be static? Link: http://lkml.kernel.org/r/20180206221005.12642-1-colin.king@canonical.com Signed-off-by: Colin Ian King <colin.king@canonical.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Khalid Aziz
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74a0496748 |
sparc64: Add support for ADI (Application Data Integrity)
ADI is a new feature supported on SPARC M7 and newer processors to allow hardware to catch rogue accesses to memory. ADI is supported for data fetches only and not instruction fetches. An app can enable ADI on its data pages, set version tags on them and use versioned addresses to access the data pages. Upper bits of the address contain the version tag. On M7 processors, upper four bits (bits 63-60) contain the version tag. If a rogue app attempts to access ADI enabled data pages, its access is blocked and processor generates an exception. Please see Documentation/sparc/adi.txt for further details. This patch extends mprotect to enable ADI (TSTATE.mcde), enable/disable MCD (Memory Corruption Detection) on selected memory ranges, enable TTE.mcd in PTEs, return ADI parameters to userspace and save/restore ADI version tags on page swap out/in or migration. ADI is not enabled by default for any task. A task must explicitly enable ADI on a memory range and set version tag for ADI to be effective for the task. Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com> Cc: Khalid Aziz <khalid@gonehiking.org> Reviewed-by: Anthony Yznaga <anthony.yznaga@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net> |
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Mike Rapoport
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b7701a5f2e |
mm: docs: fixup punctuation
so that kernel-doc will properly recognize the parameter and function descriptions. Link: http://lkml.kernel.org/r/1516700871-22279-2-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Paul E. McKenney
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08df477434 |
mm/ksm: Remove now-redundant smp_read_barrier_depends()
Because READ_ONCE() now implies smp_read_barrier_depends(), the smp_read_barrier_depends() in get_ksm_page() is now redundant. This commit removes it and updates the comments. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com> Cc: <linux-mm@kvack.org> |
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Jérôme Glisse
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0f10851ea4 |
mm/mmu_notifier: avoid double notification when it is useless
This patch only affects users of mmu_notifier->invalidate_range callback
which are device drivers related to ATS/PASID, CAPI, IOMMUv2, SVM ...
and it is an optimization for those users. Everyone else is unaffected
by it.
When clearing a pte/pmd we are given a choice to notify the event under
the page table lock (notify version of *_clear_flush helpers do call the
mmu_notifier_invalidate_range). But that notification is not necessary
in all cases.
This patch removes almost all cases where it is useless to have a call
to mmu_notifier_invalidate_range before
mmu_notifier_invalidate_range_end. It also adds documentation in all
those cases explaining why.
Below is a more in depth analysis of why this is fine to do this:
For secondary TLB (non CPU TLB) like IOMMU TLB or device TLB (when
device use thing like ATS/PASID to get the IOMMU to walk the CPU page
table to access a process virtual address space). There is only 2 cases
when you need to notify those secondary TLB while holding page table
lock when clearing a pte/pmd:
A) page backing address is free before mmu_notifier_invalidate_range_end
B) a page table entry is updated to point to a new page (COW, write fault
on zero page, __replace_page(), ...)
Case A is obvious you do not want to take the risk for the device to write
to a page that might now be used by something completely different.
Case B is more subtle. For correctness it requires the following sequence
to happen:
- take page table lock
- clear page table entry and notify (pmd/pte_huge_clear_flush_notify())
- set page table entry to point to new page
If clearing the page table entry is not followed by a notify before setting
the new pte/pmd value then you can break memory model like C11 or C++11 for
the device.
Consider the following scenario (device use a feature similar to ATS/
PASID):
Two address addrA and addrB such that |addrA - addrB| >= PAGE_SIZE we
assume they are write protected for COW (other case of B apply too).
[Time N] -----------------------------------------------------------------
CPU-thread-0 {try to write to addrA}
CPU-thread-1 {try to write to addrB}
CPU-thread-2 {}
CPU-thread-3 {}
DEV-thread-0 {read addrA and populate device TLB}
DEV-thread-2 {read addrB and populate device TLB}
[Time N+1] ---------------------------------------------------------------
CPU-thread-0 {COW_step0: {mmu_notifier_invalidate_range_start(addrA)}}
CPU-thread-1 {COW_step0: {mmu_notifier_invalidate_range_start(addrB)}}
CPU-thread-2 {}
CPU-thread-3 {}
DEV-thread-0 {}
DEV-thread-2 {}
[Time N+2] ---------------------------------------------------------------
CPU-thread-0 {COW_step1: {update page table point to new page for addrA}}
CPU-thread-1 {COW_step1: {update page table point to new page for addrB}}
CPU-thread-2 {}
CPU-thread-3 {}
DEV-thread-0 {}
DEV-thread-2 {}
[Time N+3] ---------------------------------------------------------------
CPU-thread-0 {preempted}
CPU-thread-1 {preempted}
CPU-thread-2 {write to addrA which is a write to new page}
CPU-thread-3 {}
DEV-thread-0 {}
DEV-thread-2 {}
[Time N+3] ---------------------------------------------------------------
CPU-thread-0 {preempted}
CPU-thread-1 {preempted}
CPU-thread-2 {}
CPU-thread-3 {write to addrB which is a write to new page}
DEV-thread-0 {}
DEV-thread-2 {}
[Time N+4] ---------------------------------------------------------------
CPU-thread-0 {preempted}
CPU-thread-1 {COW_step3: {mmu_notifier_invalidate_range_end(addrB)}}
CPU-thread-2 {}
CPU-thread-3 {}
DEV-thread-0 {}
DEV-thread-2 {}
[Time N+5] ---------------------------------------------------------------
CPU-thread-0 {preempted}
CPU-thread-1 {}
CPU-thread-2 {}
CPU-thread-3 {}
DEV-thread-0 {read addrA from old page}
DEV-thread-2 {read addrB from new page}
So here because at time N+2 the clear page table entry was not pair with a
notification to invalidate the secondary TLB, the device see the new value
for addrB before seing the new value for addrA. This break total memory
ordering for the device.
When changing a pte to write protect or to point to a new write protected
page with same content (KSM) it is ok to delay invalidate_range callback
to mmu_notifier_invalidate_range_end() outside the page table lock. This
is true even if the thread doing page table update is preempted right
after releasing page table lock before calling
mmu_notifier_invalidate_range_end
Thanks to Andrea for thinking of a problematic scenario for COW.
[jglisse@redhat.com: v2]
Link: http://lkml.kernel.org/r/20171017031003.7481-2-jglisse@redhat.com
Link: http://lkml.kernel.org/r/20170901173011.10745-1-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Alistair Popple <alistair@popple.id.au>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Kirill Tkhai
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4b22927f0c |
ksm: fix unlocked iteration over vmas in cmp_and_merge_page()
In this place mm is unlocked, so vmas or list may change. Down read
mmap_sem to protect them from modifications.
Link: http://lkml.kernel.org/r/150512788393.10691.8868381099691121308.stgit@localhost.localdomain
Fixes:
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Arvind Yadav
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f907c26a91 |
mm/ksm.c: constify attribute_group structures
attribute_group are not supposed to change at runtime. All functions working with attribute_group provided by <linux/sysfs.h> work with const attribute_group. So mark the non-const structs as const. Link: http://lkml.kernel.org/r/1501157167-3706-2-git-send-email-arvind.yadav.cs@gmail.com Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Minchan Kim
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b3a81d0841 |
mm: fix KSM data corruption
Nadav reported KSM can corrupt the user data by the TLB batching
race[1]. That means data user written can be lost.
Quote from Nadav Amit:
"For this race we need 4 CPUs:
CPU0: Caches a writable and dirty PTE entry, and uses the stale value
for write later.
CPU1: Runs madvise_free on the range that includes the PTE. It would
clear the dirty-bit. It batches TLB flushes.
CPU2: Writes 4 to /proc/PID/clear_refs , clearing the PTEs soft-dirty.
We care about the fact that it clears the PTE write-bit, and of
course, batches TLB flushes.
CPU3: Runs KSM. Our purpose is to pass the following test in
write_protect_page():
if (pte_write(*pvmw.pte) || pte_dirty(*pvmw.pte) ||
(pte_protnone(*pvmw.pte) && pte_savedwrite(*pvmw.pte)))
Since it will avoid TLB flush. And we want to do it while the PTE is
stale. Later, and before replacing the page, we would be able to
change the page.
Note that all the operations the CPU1-3 perform canhappen in parallel
since they only acquire mmap_sem for read.
We start with two identical pages. Everything below regards the same
page/PTE.
CPU0 CPU1 CPU2 CPU3
---- ---- ---- ----
Write the same
value on page
[cache PTE as
dirty in TLB]
MADV_FREE
pte_mkclean()
4 > clear_refs
pte_wrprotect()
write_protect_page()
[ success, no flush ]
pages_indentical()
[ ok ]
Write to page
different value
[Ok, using stale
PTE]
replace_page()
Later, CPU1, CPU2 and CPU3 would flush the TLB, but that is too late.
CPU0 already wrote on the page, but KSM ignored this write, and it got
lost"
In above scenario, MADV_FREE is fixed by changing TLB batching API
including [set|clear]_tlb_flush_pending. Remained thing is soft-dirty
part.
This patch changes soft-dirty uses TLB batching API instead of
flush_tlb_mm and KSM checks pending TLB flush by using
mm_tlb_flush_pending so that it will flush TLB to avoid data lost if
there are other parallel threads pending TLB flush.
[1] http://lkml.kernel.org/r/BD3A0EBE-ECF4-41D4-87FA-C755EA9AB6BD@gmail.com
Link: http://lkml.kernel.org/r/20170802000818.4760-8-namit@vmware.com
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Nadav Amit <namit@vmware.com>
Reported-by: Nadav Amit <namit@vmware.com>
Tested-by: Nadav Amit <namit@vmware.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Andrea Arcangeli
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80b18dfa53 |
ksm: optimize refile of stable_node_dup at the head of the chain
If a candidate stable_node_dup has been found and it can accept further merges it can be refiled to the head of the list to speedup next searches without altering which dup is found and how the dups accumulate in the chain. We already refiled it back to the head in the prune_stale_stable_nodes case, but we didn't refile it if not pruning (which is more common). And we also refiled it when it was already at the head which is unnecessary (in the prune_stale_stable_nodes case, nr > 1 means there's more than one dup in the chain, it doesn't mean it's not already at the head of the chain). The stable_node_chain list is single threaded and there's no SMP locking contention so it should be faster to refile it to the head of the list also if prune_stale_stable_nodes is false. Profiling shows the refile happens 1.9% of the time when a dup is found with a max_page_sharing limit setting of 3 (with max_page_sharing of 2 the refile never happens of course as there's never space for one more merge) which is reasonably low. At higher max_page_sharing values it should be much less frequent. This is just an optimization. Link: http://lkml.kernel.org/r/20170518173721.22316-4-aarcange@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Evgheni Dereveanchin <ederevea@redhat.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Petr Holasek <pholasek@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Gavin Guo <gavin.guo@canonical.com> Cc: Jay Vosburgh <jay.vosburgh@canonical.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Andrea Arcangeli
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8dc5ffcd5a |
ksm: swap the two output parameters of chain/chain_prune
Some static checker complains if chain/chain_prune returns a potentially stale pointer. There are two output parameters to chain/chain_prune, one is tree_page the other is stable_node_dup. Like in get_ksm_page the caller has to check tree_page is NULL before touching the stable_node. Similarly in chain/chain_prune the caller has to check tree_page before touching the stable_node_dup returned or the original stable_node passed as parameter. Because the tree_page is never returned as a stale pointer, it may be more intuitive to return tree_page and to pass stable_node_dup for reference instead of the reverse. This patch purely swaps the two output parameters of chain/chain_prune as a cleanup for the static checker and to mimic the get_ksm_page behavior more closely. There's no change to the caller at all except the swap, it's purely a cleanup and it is a noop from the caller point of view. Link: http://lkml.kernel.org/r/20170518173721.22316-3-aarcange@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Tested-by: Dan Carpenter <dan.carpenter@oracle.com> Cc: Evgheni Dereveanchin <ederevea@redhat.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Petr Holasek <pholasek@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Gavin Guo <gavin.guo@canonical.com> Cc: Jay Vosburgh <jay.vosburgh@canonical.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Andrea Arcangeli
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0ba1d0f7c4 |
ksm: cleanup stable_node chain collapse case
Patch series "KSMscale cleanup/optimizations".
There are no fixes here it's just minor cleanups and optimizations.
1/3 removes makes the "fix" for the stale stable_node fall in the
standard case without introducing new cases. Setting stable_node to
NULL was marginally safer, but stale pointer is still wiped from the
caller, this looks cleaner.
2/3 should fix the false positive from Dan's static checker.
3/3 is a microoptimization to apply the the refile of future merge
candidate dups at the head of the chain in all cases and to skip it in
one case where we did it and but it was a noop (to avoid checking if
it was already at the head but now we've to check it anyway so it got
optimized away).
This patch (of 3):
When the stable_node chain is collapsed we can as well set the caller
stable_node to match the returned stable_node_dup in chain_prune().
This way the collapse case becomes indistinguishable from the regular
stable_node case and we can remove two branches from the KSM page
migration handling slow paths.
While it was all correct this looks cleaner (and faster) as the caller has
to deal with fewer special cases.
Link: http://lkml.kernel.org/r/20170518173721.22316-2-aarcange@redhat.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Evgheni Dereveanchin <ederevea@redhat.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Petr Holasek <pholasek@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Gavin Guo <gavin.guo@canonical.com>
Cc: Jay Vosburgh <jay.vosburgh@canonical.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Andrea Arcangeli
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b4fecc67cc |
ksm: fix use after free with merge_across_nodes = 0
If merge_across_nodes was manually set to 0 (not the default value) by the admin or a tuned profile on NUMA systems triggering cross-NODE page migrations, a stable_node use after free could materialize. If the chain is collapsed stable_node would point to the old chain that was already freed. stable_node_dup would be the stable_node dup now converted to a regular stable_node and indexed in the rbtree in replacement of the freed stable_node chain (not anymore a dup). This special case where the chain is collapsed in the NUMA replacement path, is now detected by setting stable_node to NULL by the chain_prune callee if it decides to collapse the chain. This tells the NUMA replacement code that even if stable_node and stable_node_dup are different, this is not a chain if stable_node is NULL, as the stable_node_dup was converted to a regular stable_node and the chain was collapsed. It is generally safer for the callee to force the caller stable_node to NULL the moment it become stale so any other mistake like this would result in an instant Oops easier to debug than an use after free. Otherwise the replace logic would act like if stable_node was a valid chain, when in fact it was freed. Notably stable_node_chain_add_dup(page_node, stable_node) would run on a stable stable_node. Andrey Ryabinin found the source of the use after free in chain_prune(). Link: http://lkml.kernel.org/r/20170512193805.8807-2-aarcange@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reported-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reported-by: Evgheni Dereveanchin <ederevea@redhat.com> Tested-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Petr Holasek <pholasek@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Gavin Guo <gavin.guo@canonical.com> Cc: Jay Vosburgh <jay.vosburgh@canonical.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Andrea Arcangeli
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2c653d0ee2 |
ksm: introduce ksm_max_page_sharing per page deduplication limit
Without a max deduplication limit for each KSM page, the list of the rmap_items associated to each stable_node can grow infinitely large. During the rmap walk each entry can take up to ~10usec to process because of IPIs for the TLB flushing (both for the primary MMU and the secondary MMUs with the MMU notifier). With only 16GB of address space shared in the same KSM page, that would amount to dozens of seconds of kernel runtime. A ~256 max deduplication factor will reduce the latencies of the rmap walks on KSM pages to order of a few msec. Just doing the cond_resched() during the rmap walks is not enough, the list size must have a limit too, otherwise the caller could get blocked in (schedule friendly) kernel computations for seconds, unexpectedly. There's room for optimization to significantly reduce the IPI delivery cost during the page_referenced(), but at least for page_migration in the KSM case (used by hard NUMA bindings, compaction and NUMA balancing) it may be inevitable to send lots of IPIs if each rmap_item->mm is active on a different CPU and there are lots of CPUs. Even if we ignore the IPI delivery cost, we've still to walk the whole KSM rmap list, so we can't allow millions or billions (ulimited) number of entries in the KSM stable_node rmap_item lists. The limit is enforced efficiently by adding a second dimension to the stable rbtree. So there are three types of stable_nodes: the regular ones (identical as before, living in the first flat dimension of the stable rbtree), the "chains" and the "dups". Every "chain" and all "dups" linked into a "chain" enforce the invariant that they represent the same write protected memory content, even if each "dup" will be pointed by a different KSM page copy of that content. This way the stable rbtree lookup computational complexity is unaffected if compared to an unlimited max_sharing_limit. It is still enforced that there cannot be KSM page content duplicates in the stable rbtree itself. Adding the second dimension to the stable rbtree only after the max_page_sharing limit hits, provides for a zero memory footprint increase on 64bit archs. The memory overhead of the per-KSM page stable_tree and per virtual mapping rmap_item is unchanged. Only after the max_page_sharing limit hits, we need to allocate a stable_tree "chain" and rb_replace() the "regular" stable_node with the newly allocated stable_node "chain". After that we simply add the "regular" stable_node to the chain as a stable_node "dup" by linking hlist_dup in the stable_node_chain->hlist. This way the "regular" (flat) stable_node is converted to a stable_node "dup" living in the second dimension of the stable rbtree. During stable rbtree lookups the stable_node "chain" is identified as stable_node->rmap_hlist_len == STABLE_NODE_CHAIN (aka is_stable_node_chain()). When dropping stable_nodes, the stable_node "dup" is identified as stable_node->head == STABLE_NODE_DUP_HEAD (aka is_stable_node_dup()). The STABLE_NODE_DUP_HEAD must be an unique valid pointer never used elsewhere in any stable_node->head/node to avoid a clashes with the stable_node->node.rb_parent_color pointer, and different from &migrate_nodes. So the second field of &migrate_nodes is picked and verified as always safe with a BUILD_BUG_ON in case the list_head implementation changes in the future. The STABLE_NODE_DUP is picked as a random negative value in stable_node->rmap_hlist_len. rmap_hlist_len cannot become negative when it's a "regular" stable_node or a stable_node "dup". The stable_node_chain->nid is irrelevant. The stable_node_chain->kpfn is aliased in a union with a time field used to rate limit the stable_node_chain->hlist prunes. The garbage collection of the stable_node_chain happens lazily during stable rbtree lookups (as for all other kind of stable_nodes), or while disabling KSM with "echo 2 >/sys/kernel/mm/ksm/run" while collecting the entire stable rbtree. While the "regular" stable_nodes and the stable_node "dups" must wait for their underlying tree_page to be freed before they can be freed themselves, the stable_node "chains" can be freed immediately if the stable_node->hlist turns empty. This is because the "chains" are never pointed by any page->mapping and they're effectively stable rbtree KSM self contained metadata. [akpm@linux-foundation.org: fix non-NUMA build] Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Tested-by: Petr Holasek <pholasek@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Evgheni Dereveanchin <ederevea@redhat.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Gavin Guo <gavin.guo@canonical.com> Cc: Jay Vosburgh <jay.vosburgh@canonical.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Andrea Arcangeli
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a7306c3436 |
ksm: prevent crash after write_protect_page fails
"err" needs to be left set to -EFAULT if split_huge_page succeeds. Otherwise if "err" gets clobbered with zero and write_protect_page fails, try_to_merge_one_page() will succeed instead of returning -EFAULT and then try_to_merge_with_ksm_page() will continue thinking kpage is a PageKsm when in fact it's still an anonymous page. Eventually it'll crash in page_add_anon_rmap. This has been reproduced on Fedora25 kernel but I can reproduce with upstream too. The bug was introduced in commit |
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Minchan Kim
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e4b8222271 |
mm: make rmap_one boolean function
rmap_one's return value controls whether rmap_work should contine to scan other ptes or not so it's target for changing to boolean. Return true if the scan should be continued. Otherwise, return false to stop the scanning. This patch makes rmap_one's return value to boolean. Link: http://lkml.kernel.org/r/1489555493-14659-10-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.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> |
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Minchan Kim
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1df631ae19 |
mm: make rmap_walk() return void
There is no user of the return value from rmap_walk() and friends so this patch makes them void-returning functions. Link: http://lkml.kernel.org/r/1489555493-14659-9-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.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> |
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Ingo Molnar
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f7ccbae45c |
sched/headers: Prepare for new header dependencies before moving code to <linux/sched/coredump.h>
We are going to split <linux/sched/coredump.h> out of <linux/sched.h>, which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder <linux/sched/coredump.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Ingo Molnar
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6e84f31522 |
sched/headers: Prepare for new header dependencies before moving code to <linux/sched/mm.h>
We are going to split <linux/sched/mm.h> out of <linux/sched.h>, which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder <linux/sched/mm.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. The APIs that are going to be moved first are: mm_alloc() __mmdrop() mmdrop() mmdrop_async_fn() mmdrop_async() mmget_not_zero() mmput() mmput_async() get_task_mm() mm_access() mm_release() Include the new header in the files that are going to need it. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Vegard Nossum
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f1f1007644 |
mm: add new mmgrab() helper
Apart from adding the helper function itself, the rest of the kernel is converted mechanically using: git grep -l 'atomic_inc.*mm_count' | xargs sed -i 's/atomic_inc(&\(.*\)->mm_count);/mmgrab\(\1\);/' git grep -l 'atomic_inc.*mm_count' | xargs sed -i 's/atomic_inc(&\(.*\)\.mm_count);/mmgrab\(\&\1\);/' This is needed for a later patch that hooks into the helper, but might be a worthwhile cleanup on its own. (Michal Hocko provided most of the kerneldoc comment.) Link: http://lkml.kernel.org/r/20161218123229.22952-1-vegard.nossum@oracle.com Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> 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> |
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Aneesh Kumar K.V
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595cd8f256 |
mm/ksm: handle protnone saved writes when making page write protect
Without this KSM will consider the page write protected, but a numa fault can later mark the page writable. This can result in memory corruption. Link: http://lkml.kernel.org/r/1487498625-10891-3-git-send-email-aneesh.kumar@linux.vnet.ibm.com Signed-off-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> |
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Kirill A. Shutemov
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36eaff3364 |
mm, ksm: convert write_protect_page() to use page_vma_mapped_walk()
For consistency, it worth converting all page_check_address() to page_vma_mapped_walk(), so we could drop the former. Link: http://lkml.kernel.org/r/20170129173858.45174-9-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Claudio Imbrenda
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e86c59b1b1 |
mm/ksm: improve deduplication of zero pages with colouring
Some architectures have a set of zero pages (coloured zero pages) instead of only one zero page, in order to improve the cache performance. In those cases, the kernel samepage merger (KSM) would merge all the allocated pages that happen to be filled with zeroes to the same deduplicated page, thus losing all the advantages of coloured zero pages. This behaviour is noticeable when a process accesses large arrays of allocated pages containing zeroes. A test I conducted on s390 shows that there is a speed penalty when KSM merges such pages, compared to not merging them or using actual zero pages from the start without breaking the COW. This patch fixes this behaviour. When coloured zero pages are present, the checksum of a zero page is calculated during initialisation, and compared with the checksum of the current canditate during merging. In case of a match, the normal merging routine is used to merge the page with the correct coloured zero page, which ensures the candidate page is checked to be equal to the target zero page. A sysfs entry is also added to toggle this behaviour, since it can potentially introduce performance regressions, especially on architectures without coloured zero pages. The default value is disabled, for backwards compatibility. With this patch, the performance with KSM is the same as with non COW-broken actual zero pages, which is also the same as without KSM. [akpm@linux-foundation.org: make zero_checksum and ksm_use_zero_pages __read_mostly, per Andrea] [imbrenda@linux.vnet.ibm.com: documentation for coloured zero pages deduplication] Link: http://lkml.kernel.org/r/1484927522-1964-1-git-send-email-imbrenda@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1484850953-23941-1-git-send-email-imbrenda@linux.vnet.ibm.com Signed-off-by: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Hugh Dickins <hughd@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> |
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zhong jiang
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6213055f2c |
mm,ksm: add __GFP_HIGH to the allocation in alloc_stable_node()
According to Hugh's suggestion, alloc_stable_node() with GFP_KERNEL can in rare cases cause a hung task warning. At present, if alloc_stable_node() allocation fails, two break_cows may want to allocate a couple of pages, and the issue will come up when free memory is under pressure. We fix it by adding __GFP_HIGH to GFP, to grant access to memory reserves, increasing the likelihood of allocation success. [akpm@linux-foundation.org: tweak comment] Link: http://lkml.kernel.org/r/1474354484-58233-1-git-send-email-zhongjiang@huawei.com Signed-off-by: zhong jiang <zhongjiang@huawei.com> Suggested-by: Hugh Dickins <hughd@google.com> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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zhong jiang
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5b398e416e |
mm,ksm: fix endless looping in allocating memory when ksm enable
I hit the following hung task when runing a OOM LTP test case with 4.1 kernel. Call trace: [<ffffffc000086a88>] __switch_to+0x74/0x8c [<ffffffc000a1bae0>] __schedule+0x23c/0x7bc [<ffffffc000a1c09c>] schedule+0x3c/0x94 [<ffffffc000a1eb84>] rwsem_down_write_failed+0x214/0x350 [<ffffffc000a1e32c>] down_write+0x64/0x80 [<ffffffc00021f794>] __ksm_exit+0x90/0x19c [<ffffffc0000be650>] mmput+0x118/0x11c [<ffffffc0000c3ec4>] do_exit+0x2dc/0xa74 [<ffffffc0000c46f8>] do_group_exit+0x4c/0xe4 [<ffffffc0000d0f34>] get_signal+0x444/0x5e0 [<ffffffc000089fcc>] do_signal+0x1d8/0x450 [<ffffffc00008a35c>] do_notify_resume+0x70/0x78 The oom victim cannot terminate because it needs to take mmap_sem for write while the lock is held by ksmd for read which loops in the page allocator ksm_do_scan scan_get_next_rmap_item down_read get_next_rmap_item alloc_rmap_item #ksmd will loop permanently. There is no way forward because the oom victim cannot release any memory in 4.1 based kernel. Since 4.6 we have the oom reaper which would solve this problem because it would release the memory asynchronously. Nevertheless we can relax alloc_rmap_item requirements and use __GFP_NORETRY because the allocation failure is acceptable as ksm_do_scan would just retry later after the lock got dropped. Such a patch would be also easy to backport to older stable kernels which do not have oom_reaper. While we are at it add GFP_NOWARN so the admin doesn't have to be alarmed by the allocation failure. Link: http://lkml.kernel.org/r/1474165570-44398-1-git-send-email-zhongjiang@huawei.com Signed-off-by: zhong jiang <zhongjiang@huawei.com> Suggested-by: Hugh Dickins <hughd@google.com> Suggested-by: Michal Hocko <mhocko@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Kirill A. Shutemov
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dcddffd41d |
mm: do not pass mm_struct into handle_mm_fault
We always have vma->vm_mm around. Link: http://lkml.kernel.org/r/1466021202-61880-8-git-send-email-kirill.shutemov@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> |
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Minchan Kim
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bda807d444 |
mm: migrate: support non-lru movable page migration
We have allowed migration for only LRU pages until now and it was enough to make high-order pages. But recently, embedded system(e.g., webOS, android) uses lots of non-movable pages(e.g., zram, GPU memory) so we have seen several reports about troubles of small high-order allocation. For fixing the problem, there were several efforts (e,g,. enhance compaction algorithm, SLUB fallback to 0-order page, reserved memory, vmalloc and so on) but if there are lots of non-movable pages in system, their solutions are void in the long run. So, this patch is to support facility to change non-movable pages with movable. For the feature, this patch introduces functions related to migration to address_space_operations as well as some page flags. If a driver want to make own pages movable, it should define three functions which are function pointers of struct address_space_operations. 1. bool (*isolate_page) (struct page *page, isolate_mode_t mode); What VM expects on isolate_page function of driver is to return *true* if driver isolates page successfully. On returing true, VM marks the page as PG_isolated so concurrent isolation in several CPUs skip the page for isolation. If a driver cannot isolate the page, it should return *false*. Once page is successfully isolated, VM uses page.lru fields so driver shouldn't expect to preserve values in that fields. 2. int (*migratepage) (struct address_space *mapping, struct page *newpage, struct page *oldpage, enum migrate_mode); After isolation, VM calls migratepage of driver with isolated page. The function of migratepage is to move content of the old page to new page and set up fields of struct page newpage. Keep in mind that you should indicate to the VM the oldpage is no longer movable via __ClearPageMovable() under page_lock if you migrated the oldpage successfully and returns 0. If driver cannot migrate the page at the moment, driver can return -EAGAIN. On -EAGAIN, VM will retry page migration in a short time because VM interprets -EAGAIN as "temporal migration failure". On returning any error except -EAGAIN, VM will give up the page migration without retrying in this time. Driver shouldn't touch page.lru field VM using in the functions. 3. void (*putback_page)(struct page *); If migration fails on isolated page, VM should return the isolated page to the driver so VM calls driver's putback_page with migration failed page. In this function, driver should put the isolated page back to the own data structure. 4. non-lru movable page flags There are two page flags for supporting non-lru movable page. * PG_movable Driver should use the below function to make page movable under page_lock. void __SetPageMovable(struct page *page, struct address_space *mapping) It needs argument of address_space for registering migration family functions which will be called by VM. Exactly speaking, PG_movable is not a real flag of struct page. Rather than, VM reuses page->mapping's lower bits to represent it. #define PAGE_MAPPING_MOVABLE 0x2 page->mapping = page->mapping | PAGE_MAPPING_MOVABLE; so driver shouldn't access page->mapping directly. Instead, driver should use page_mapping which mask off the low two bits of page->mapping so it can get right struct address_space. For testing of non-lru movable page, VM supports __PageMovable function. However, it doesn't guarantee to identify non-lru movable page because page->mapping field is unified with other variables in struct page. As well, if driver releases the page after isolation by VM, page->mapping doesn't have stable value although it has PAGE_MAPPING_MOVABLE (Look at __ClearPageMovable). But __PageMovable is cheap to catch whether page is LRU or non-lru movable once the page has been isolated. Because LRU pages never can have PAGE_MAPPING_MOVABLE in page->mapping. It is also good for just peeking to test non-lru movable pages before more expensive checking with lock_page in pfn scanning to select victim. For guaranteeing non-lru movable page, VM provides PageMovable function. Unlike __PageMovable, PageMovable functions validates page->mapping and mapping->a_ops->isolate_page under lock_page. The lock_page prevents sudden destroying of page->mapping. Driver using __SetPageMovable should clear the flag via __ClearMovablePage under page_lock before the releasing the page. * PG_isolated To prevent concurrent isolation among several CPUs, VM marks isolated page as PG_isolated under lock_page. So if a CPU encounters PG_isolated non-lru movable page, it can skip it. Driver doesn't need to manipulate the flag because VM will set/clear it automatically. Keep in mind that if driver sees PG_isolated page, it means the page have been isolated by VM so it shouldn't touch page.lru field. PG_isolated is alias with PG_reclaim flag so driver shouldn't use the flag for own purpose. [opensource.ganesh@gmail.com: mm/compaction: remove local variable is_lru] Link: http://lkml.kernel.org/r/20160618014841.GA7422@leo-test Link: http://lkml.kernel.org/r/1464736881-24886-3-git-send-email-minchan@kernel.org Signed-off-by: Gioh Kim <gi-oh.kim@profitbricks.com> Signed-off-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Ganesh Mahendran <opensource.ganesh@gmail.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Rafael Aquini <aquini@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: John Einar Reitan <john.reitan@foss.arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
|
|
Zhou Chengming
|
7496fea9a6 |
ksm: fix conflict between mmput and scan_get_next_rmap_item
A concurrency issue about KSM in the function scan_get_next_rmap_item.
task A (ksmd): |task B (the mm's task):
|
mm = slot->mm; |
down_read(&mm->mmap_sem); |
|
... |
|
spin_lock(&ksm_mmlist_lock); |
|
ksm_scan.mm_slot go to the next slot; |
|
spin_unlock(&ksm_mmlist_lock); |
|mmput() ->
| ksm_exit():
|
|spin_lock(&ksm_mmlist_lock);
|if (mm_slot && ksm_scan.mm_slot != mm_slot) {
| if (!mm_slot->rmap_list) {
| easy_to_free = 1;
| ...
|
|if (easy_to_free) {
| mmdrop(mm);
| ...
|
|So this mm_struct may be freed in the mmput().
|
up_read(&mm->mmap_sem); |
As we can see above, the ksmd thread may access a mm_struct that already
been freed to the kmem_cache. Suppose a fork will get this mm_struct from
the kmem_cache, the ksmd thread then call up_read(&mm->mmap_sem), will
cause mmap_sem.count to become -1.
As suggested by Andrea Arcangeli, unmerge_and_remove_all_rmap_items has
the same SMP race condition, so fix it too. My prev fix in function
scan_get_next_rmap_item will introduce a different SMP race condition, so
just invert the up_read/spin_unlock order as Andrea Arcangeli said.
Link: http://lkml.kernel.org/r/1462708815-31301-1-git-send-email-zhouchengming1@huawei.com
Signed-off-by: Zhou Chengming <zhouchengming1@huawei.com>
Suggested-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Geliang Tang <geliangtang@163.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Ding Tianhong <dingtianhong@huawei.com>
Cc: Li Bin <huawei.libin@huawei.com>
Cc: Zhen Lei <thunder.leizhen@huawei.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
|
Dave Hansen
|
1b2ee1266e |
mm/core: Do not enforce PKEY permissions on remote mm access
We try to enforce protection keys in software the same way that we do in hardware. (See long example below). But, we only want to do this when accessing our *own* process's memory. If GDB set PKRU[6].AD=1 (disable access to PKEY 6), then tried to PTRACE_POKE a target process which just happened to have some mprotect_pkey(pkey=6) memory, we do *not* want to deny the debugger access to that memory. PKRU is fundamentally a thread-local structure and we do not want to enforce it on access to _another_ thread's data. This gets especially tricky when we have workqueues or other delayed-work mechanisms that might run in a random process's context. We can check that we only enforce pkeys when operating on our *own* mm, but delayed work gets performed when a random user context is active. We might end up with a situation where a delayed-work gup fails when running randomly under its "own" task but succeeds when running under another process. We want to avoid that. To avoid that, we use the new GUP flag: FOLL_REMOTE and add a fault flag: FAULT_FLAG_REMOTE. They indicate that we are walking an mm which is not guranteed to be the same as current->mm and should not be subject to protection key enforcement. Thanks to Jerome Glisse for pointing out this scenario. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Alexey Kardashevskiy <aik@ozlabs.ru> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Boaz Harrosh <boaz@plexistor.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Chinner <dchinner@redhat.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Dominik Dingel <dingel@linux.vnet.ibm.com> Cc: Dominik Vogt <vogt@linux.vnet.ibm.com> Cc: Eric B Munson <emunson@akamai.com> Cc: Geliang Tang <geliangtang@163.com> Cc: Guan Xuetao <gxt@mprc.pku.edu.cn> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jason Low <jason.low2@hp.com> Cc: Jerome Marchand <jmarchan@redhat.com> Cc: Joerg Roedel <joro@8bytes.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Laurent Dufour <ldufour@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Matthew Wilcox <willy@linux.intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Hocko <mhocko@suse.com> Cc: Mikulas Patocka <mpatocka@redhat.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Shachar Raindel <raindel@mellanox.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Xie XiuQi <xiexiuqi@huawei.com> Cc: iommu@lists.linux-foundation.org Cc: linux-arch@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org Cc: linux-s390@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
|
|
Dave Hansen
|
d4edcf0d56 |
mm/gup: Switch all callers of get_user_pages() to not pass tsk/mm
We will soon modify the vanilla get_user_pages() so it can no longer be used on mm/tasks other than 'current/current->mm', which is by far the most common way it is called. For now, we allow the old-style calls, but warn when they are used. (implemented in previous patch) This patch switches all callers of: get_user_pages() get_user_pages_unlocked() get_user_pages_locked() to stop passing tsk/mm so they will no longer see the warnings. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave@sr71.net> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: jack@suse.cz Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20160212210156.113E9407@viggo.jf.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
|
|
Minchan Kim
|
337ed7eb5f |
mm/ksm.c: mark stable page dirty
The MADV_FREE patchset changes page reclaim to simply free a clean anonymous page with no dirty ptes, instead of swapping it out; but KSM uses clean write-protected ptes to reference the stable ksm page. So be sure to mark that page dirty, so it's never mistakenly discarded. [hughd@google.com: adjusted comments] Signed-off-by: Minchan Kim <minchan@kernel.org> Acked-by: Hugh Dickins <hughd@google.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: Andrea Arcangeli <aarcange@redhat.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: Kirill A. Shutemov <kirill@shutemov.name> 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> |
|
|
Kirill A. Shutemov
|
f765f54059 |
ksm: prepare to new THP semantics
We don't need special code to stabilize THP. If you've got reference to any subpage of THP it will not be split under you. New split_huge_page() also accepts tail pages: no need in special code to get reference to head page. 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> |
|
|
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> |
|
|
Kirill A. Shutemov
|
48c935ad88 |
page-flags: define PG_locked behavior on compound pages
lock_page() must operate on the whole compound page. It doesn't make much sense to lock part of compound page. Change code to use head page's PG_locked, if tail page is passed. This patch also gets rid of custom helper functions -- __set_page_locked() and __clear_page_locked(). They are replaced with helpers generated by __SETPAGEFLAG/__CLEARPAGEFLAG. Tail pages to these helper would trigger VM_BUG_ON(). SLUB uses PG_locked as a bit spin locked. IIUC, tail pages should never appear there. VM_BUG_ON() is added to make sure that this assumption is correct. [akpm@linux-foundation.org: fix fs/cifs/file.c] Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.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> Cc: Jérôme Glisse <jglisse@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
|
|
Geliang Tang
|
036404183e |
mm/ksm.c: use list_for_each_entry_safe
Use list_for_each_entry_safe() instead of list_for_each_safe() to simplify the code. Signed-off-by: Geliang Tang <geliangtang@163.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> |
|
|
Andrea Arcangeli
|
c8f95ed1a9 |
ksm: unstable_tree_search_insert error checking cleanup
get_mergeable_page() can only return NULL (also in case of errors) or the pinned mergeable page. It can't return an error different than NULL. This optimizes away the unnecessary error check. Add a return after the "out:" label in the callee to make it more readable. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Petr Holasek <pholasek@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
|
|
Andrea Arcangeli
|
85c6e8dd23 |
ksm: use find_mergeable_vma in try_to_merge_with_ksm_page
Doing the VM_MERGEABLE check after the page == kpage check won't provide any meaningful benefit. The !vma->anon_vma check of find_mergeable_vma is the only superfluous bit in using find_mergeable_vma because the !PageAnon check of try_to_merge_one_page() implicitly checks for that, but it still looks cleaner to share the same find_mergeable_vma(). Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Petr Holasek <pholasek@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
|
|
Andrea Arcangeli
|
98666f8a25 |
ksm: use the helper method to do the hlist_empty check
This just uses the helper function to cleanup the assumption on the hlist_node internals. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Petr Holasek <pholasek@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
|
|
Andrea Arcangeli
|
f2e5ff85ed |
ksm: don't fail stable tree lookups if walking over stale stable_nodes
The stable_nodes can become stale at any time if the underlying pages gets freed. The stable_node gets collected and removed from the stable rbtree if that is detected during the rbtree lookups. Don't fail the lookup if running into stale stable_nodes, just restart the lookup after collecting the stale stable_nodes. Otherwise the CPU spent in the preparation stage is wasted and the lookup must be repeated at the next loop potentially failing a second time in a second stale stable_node. If we don't prune aggressively we delay the merging of the unstable node candidates and at the same time we delay the freeing of the stale stable_nodes. Keeping stale stable_nodes around wastes memory and it can't provide any benefit. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Petr Holasek <pholasek@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
|
|
Andrea Arcangeli
|
ad12695f17 |
ksm: add cond_resched() to the rmap_walks
While at it add it to the file and anon walks too. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Petr Holasek <pholasek@redhat.com> Acked-by: Davidlohr Bueso <dbueso@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
|
|
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> |
|
|
Kirill A. Shutemov
|
0661a33611 |
mm: remove rest usage of VM_NONLINEAR and pte_file()
One bit in ->vm_flags is unused now! Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
|
|
Linus Torvalds
|
33692f2759 |
vm: add VM_FAULT_SIGSEGV handling support
The core VM already knows about VM_FAULT_SIGBUS, but cannot return a
"you should SIGSEGV" error, because the SIGSEGV case was generally
handled by the caller - usually the architecture fault handler.
That results in lots of duplication - all the architecture fault
handlers end up doing very similar "look up vma, check permissions, do
retries etc" - but it generally works. However, there are cases where
the VM actually wants to SIGSEGV, and applications _expect_ SIGSEGV.
In particular, when accessing the stack guard page, libsigsegv expects a
SIGSEGV. And it usually got one, because the stack growth is handled by
that duplicated architecture fault handler.
However, when the generic VM layer started propagating the error return
from the stack expansion in commit
|
|
|
Joerg Roedel
|
34ee645e83 |
mmu_notifier: call mmu_notifier_invalidate_range() from VMM
Add calls to the new mmu_notifier_invalidate_range() function to all places in the VMM that need it. Signed-off-by: Joerg Roedel <jroedel@suse.de> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Reviewed-by: Jérôme Glisse <jglisse@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Rik van Riel <riel@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Jay Cornwall <Jay.Cornwall@amd.com> Cc: Oded Gabbay <Oded.Gabbay@amd.com> Cc: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com> Cc: Jesse Barnes <jbarnes@virtuousgeek.org> Cc: David Woodhouse <dwmw2@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Oded Gabbay <oded.gabbay@amd.com> |