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  1. 09 9月, 2017 1 次提交
    • Z
      mm: thp: check pmd migration entry in common path · 84c3fc4e
      由 Zi Yan 提交于 
      When THP migration is being used, memory management code needs to handle
pmd migration entries properly.  This patch uses !pmd_present() or
is_swap_pmd() (depending on whether pmd_none() needs separate code or
not) to check pmd migration entries at the places where a pmd entry is
present.

Since pmd-related code uses split_huge_page(), split_huge_pmd(),
pmd_trans_huge(), pmd_trans_unstable(), or
pmd_none_or_trans_huge_or_clear_bad(), this patch:

1. adds pmd migration entry split code in split_huge_pmd(),

2. takes care of pmd migration entries whenever pmd_trans_huge() is present,

3. makes pmd_none_or_trans_huge_or_clear_bad() pmd migration entry aware.

Since split_huge_page() uses split_huge_pmd() and pmd_trans_unstable()
is equivalent to pmd_none_or_trans_huge_or_clear_bad(), we do not change
them.

Until this commit, a pmd entry should be:
1. pointing to a pte page,
2. is_swap_pmd(),
3. pmd_trans_huge(),
4. pmd_devmap(), or
5. pmd_none().
Signed-off-by: NZi Yan <zi.yan@cs.rutgers.edu>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      84c3fc4e
  3. 07 9月, 2017 1 次提交
  5. 03 8月, 2017 2 次提交
    • M
      userfaultfd: non-cooperative: notify about unmap of destination during mremap · b2282371
      由 Mike Rapoport 提交于 
      When mremap is called with MREMAP_FIXED it unmaps memory at the
destination address without notifying userfaultfd monitor.

If the destination were registered with userfaultfd, the monitor has no
way to distinguish between the old and new ranges and to properly relate
the page faults that would occur in the destination region.

Fixes: 897ab3e0 ("userfaultfd: non-cooperative: add event for memory unmaps")
Link: http://lkml.kernel.org/r/1500276876-3350-1-git-send-email-rppt@linux.vnet.ibm.comSigned-off-by: NMike Rapoport <rppt@linux.vnet.ibm.com>
Acked-by: NPavel Emelyanov <xemul@virtuozzo.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      b2282371
    • M
      mm, mprotect: flush TLB if potentially racing with a parallel reclaim leaving stale TLB entries · 3ea27719
      由 Mel Gorman 提交于 
      Nadav Amit identified a theoritical race between page reclaim and
mprotect due to TLB flushes being batched outside of the PTL being held.

He described the race as follows:

        CPU0                            CPU1
        ----                            ----
                                        user accesses memory using RW PTE
                                        [PTE now cached in TLB]
        try_to_unmap_one()
        ==> ptep_get_and_clear()
        ==> set_tlb_ubc_flush_pending()
                                        mprotect(addr, PROT_READ)
                                        ==> change_pte_range()
                                        ==> [ PTE non-present - no flush ]

                                        user writes using cached RW PTE
        ...

        try_to_unmap_flush()

The same type of race exists for reads when protecting for PROT_NONE and
also exists for operations that can leave an old TLB entry behind such
as munmap, mremap and madvise.

For some operations like mprotect, it's not necessarily a data integrity
issue but it is a correctness issue as there is a window where an
mprotect that limits access still allows access.  For munmap, it's
potentially a data integrity issue although the race is massive as an
munmap, mmap and return to userspace must all complete between the
window when reclaim drops the PTL and flushes the TLB.  However, it's
theoritically possible so handle this issue by flushing the mm if
reclaim is potentially currently batching TLB flushes.

Other instances where a flush is required for a present pte should be ok
as either the page lock is held preventing parallel reclaim or a page
reference count is elevated preventing a parallel free leading to
corruption.  In the case of page_mkclean there isn't an obvious path
that userspace could take advantage of without using the operations that
are guarded by this patch.  Other users such as gup as a race with
reclaim looks just at PTEs.  huge page variants should be ok as they
don't race with reclaim.  mincore only looks at PTEs.  userfault also
should be ok as if a parallel reclaim takes place, it will either fault
the page back in or read some of the data before the flush occurs
triggering a fault.

Note that a variant of this patch was acked by Andy Lutomirski but this
was for the x86 parts on top of his PCID work which didn't make the 4.13
merge window as expected.  His ack is dropped from this version and
there will be a follow-on patch on top of PCID that will include his
ack.

[akpm@linux-foundation.org: tweak comments]
[akpm@linux-foundation.org: fix spello]
Link: http://lkml.kernel.org/r/20170717155523.emckq2esjro6hf3z@suse.deReported-by: NNadav Amit <nadav.amit@gmail.com>
Signed-off-by: NMel Gorman <mgorman@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: <stable@vger.kernel.org>	[v4.4+]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      3ea27719
  7. 10 3月, 2017 1 次提交
  9. 25 2月, 2017 1 次提交
  11. 23 2月, 2017 2 次提交
  13. 30 11月, 2016 1 次提交
  15. 18 11月, 2016 1 次提交
    • A
      mremap: fix race between mremap() and page cleanning · 5d190420
      由 Aaron Lu 提交于 
      Prior to 3.15, there was a race between zap_pte_range() and
page_mkclean() where writes to a page could be lost.  Dave Hansen
discovered by inspection that there is a similar race between
move_ptes() and page_mkclean().

We've been able to reproduce the issue by enlarging the race window with
a msleep(), but have not been able to hit it without modifying the code.
So, we think it's a real issue, but is difficult or impossible to hit in
practice.

The zap_pte_range() issue is fixed by commit 1cf35d47("mm: split
'tlb_flush_mmu()' into tlb flushing and memory freeing parts").  And
this patch is to fix the race between page_mkclean() and mremap().

Here is one possible way to hit the race: suppose a process mmapped a
file with READ | WRITE and SHARED, it has two threads and they are bound
to 2 different CPUs, e.g.  CPU1 and CPU2.  mmap returned X, then thread
1 did a write to addr X so that CPU1 now has a writable TLB for addr X
on it.  Thread 2 starts mremaping from addr X to Y while thread 1
cleaned the page and then did another write to the old addr X again.
The 2nd write from thread 1 could succeed but the value will get lost.

        thread 1                           thread 2
     (bound to CPU1)                    (bound to CPU2)

  1: write 1 to addr X to get a
     writeable TLB on this CPU

                                        2: mremap starts

                                        3: move_ptes emptied PTE for addr X
                                           and setup new PTE for addr Y and
                                           then dropped PTL for X and Y

  4: page laundering for N by doing
     fadvise FADV_DONTNEED. When done,
     pageframe N is deemed clean.

  5: *write 2 to addr X

                                        6: tlb flush for addr X

  7: munmap (Y, pagesize) to make the
     page unmapped

  8: fadvise with FADV_DONTNEED again
     to kick the page off the pagecache

  9: pread the page from file to verify
     the value. If 1 is there, it means
     we have lost the written 2.

  *the write may or may not cause segmentation fault, it depends on
  if the TLB is still on the CPU.

Please note that this is only one specific way of how the race could
occur, it didn't mean that the race could only occur in exact the above
config, e.g. more than 2 threads could be involved and fadvise() could
be done in another thread, etc.

For anonymous pages, they could race between mremap() and page reclaim:
THP: a huge PMD is moved by mremap to a new huge PMD, then the new huge
PMD gets unmapped/splitted/pagedout before the flush tlb happened for
the old huge PMD in move_page_tables() and we could still write data to
it.  The normal anonymous page has similar situation.

To fix this, check for any dirty PTE in move_ptes()/move_huge_pmd() and
if any, did the flush before dropping the PTL.  If we did the flush for
every move_ptes()/move_huge_pmd() call then we do not need to do the
flush in move_pages_tables() for the whole range.  But if we didn't, we
still need to do the whole range flush.

Alternatively, we can track which part of the range is flushed in
move_ptes()/move_huge_pmd() and which didn't to avoid flushing the whole
range in move_page_tables().  But that would require multiple tlb
flushes for the different sub-ranges and should be less efficient than
the single whole range flush.

KBuild test on my Sandybridge desktop doesn't show any noticeable change.
v4.9-rc4:
  real    5m14.048s
  user    32m19.800s
  sys     4m50.320s

With this commit:
  real    5m13.888s
  user    32m19.330s
  sys     4m51.200s
Reported-by: NDave Hansen <dave.hansen@intel.com>
Signed-off-by: NAaron Lu <aaron.lu@intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      5d190420
  17. 27 7月, 2016 1 次提交
  19. 24 5月, 2016 1 次提交
    • M
      mm: make mmap_sem for write waits killable for mm syscalls · dc0ef0df
      由 Michal Hocko 提交于 
      This is a follow up work for oom_reaper [1].  As the async OOM killing
depends on oom_sem for read we would really appreciate if a holder for
write didn't stood in the way.  This patchset is changing many of
down_write calls to be killable to help those cases when the writer is
blocked and waiting for readers to release the lock and so help
__oom_reap_task to process the oom victim.

Most of the patches are really trivial because the lock is help from a
shallow syscall paths where we can return EINTR trivially and allow the
current task to die (note that EINTR will never get to the userspace as
the task has fatal signal pending).  Others seem to be easy as well as
the callers are already handling fatal errors and bail and return to
userspace which should be sufficient to handle the failure gracefully.
I am not familiar with all those code paths so a deeper review is really
appreciated.

As this work is touching more areas which are not directly connected I
have tried to keep the CC list as small as possible and people who I
believed would be familiar are CCed only to the specific patches (all
should have received the cover though).

This patchset is based on linux-next and it depends on
down_write_killable for rw_semaphores which got merged into tip
locking/rwsem branch and it is merged into this next tree.  I guess it
would be easiest to route these patches via mmotm because of the
dependency on the tip tree but if respective maintainers prefer other
way I have no objections.

I haven't covered all the mmap_write(mm->mmap_sem) instances here

  $ git grep "down_write(.*\<mmap_sem\>)" next/master | wc -l
  98
  $ git grep "down_write(.*\<mmap_sem\>)" | wc -l
  62

I have tried to cover those which should be relatively easy to review in
this series because this alone should be a nice improvement.  Other
places can be changed on top.

[0] http://lkml.kernel.org/r/1456752417-9626-1-git-send-email-mhocko@kernel.org
[1] http://lkml.kernel.org/r/1452094975-551-1-git-send-email-mhocko@kernel.org
[2] http://lkml.kernel.org/r/1456750705-7141-1-git-send-email-mhocko@kernel.org

This patch (of 18):

This is the first step in making mmap_sem write waiters killable.  It
focuses on the trivial ones which are taking the lock early after
entering the syscall and they are not changing state before.

Therefore it is very easy to change them to use down_write_killable and
immediately return with -EINTR.  This will allow the waiter to pass away
without blocking the mmap_sem which might be required to make a forward
progress.  E.g.  the oom reaper will need the lock for reading to
dismantle the OOM victim address space.

The only tricky function in this patch is vm_mmap_pgoff which has many
call sites via vm_mmap.  To reduce the risk keep vm_mmap with the
original non-killable semantic for now.

vm_munmap callers do not bother checking the return value so open code
it into the munmap syscall path for now for simplicity.
Signed-off-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      dc0ef0df
  21. 20 5月, 2016 2 次提交
    • H
      huge pagecache: extend mremap pmd rmap lockout to files · 1d069b7d
      由 Hugh Dickins 提交于 
      Whatever huge pagecache implementation we go with, file rmap locking
must be added to anon rmap locking, when mremap's move_page_tables()
finds a pmd_trans_huge pmd entry: a simple change, let's do it now.

Factor out take_rmap_locks() and drop_rmap_locks() to handle the locking
for make move_ptes() and move_page_tables(), and delete the
VM_BUG_ON_VMA which rejected vm_file and required anon_vma.
Signed-off-by: NHugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Yang Shi <yang.shi@linaro.org>
Cc: Ning Qu <quning@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      1d069b7d
    • H
      huge mm: move_huge_pmd does not need new_vma · bf8616d5
      由 Hugh Dickins 提交于 
      Remove move_huge_pmd()'s redundant new_vma arg: all it was used for was
a VM_NOHUGEPAGE check on new_vma flags, but the new_vma is cloned from
the old vma, so a trans_huge_pmd in the new_vma will be as acceptable as
it was in the old vma, alignment and size permitting.
Signed-off-by: NHugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Yang Shi <yang.shi@linaro.org>
Cc: Ning Qu <quning@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      bf8616d5
  23. 18 3月, 2016 2 次提交
  25. 12 2月, 2016 1 次提交
    • K
      mm, dax: check for pmd_none() after split_huge_pmd() · 6b9116a6
      由 Kirill A. Shutemov 提交于 
      DAX implements split_huge_pmd() by clearing pmd.  This simple approach
reduces memory overhead, as we don't need to deposit page table on huge
page mapping to make split_huge_pmd() never-fail.  PTE table can be
allocated and populated later on page fault from backing store.

But one side effect is that have to check if pmd is pmd_none() after
split_huge_pmd().  In most places we do this already to deal with
parallel MADV_DONTNEED.

But I found two call sites which is not affected by MADV_DONTNEED (due
down_write(mmap_sem)), but need to have the check to work with DAX
properly.
Signed-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      6b9116a6
  27. 16 1月, 2016 2 次提交
  29. 15 1月, 2016 1 次提交
    • K
      mm: rework virtual memory accounting · 84638335
      由 Konstantin Khlebnikov 提交于 
      When inspecting a vague code inside prctl(PR_SET_MM_MEM) call (which
testing the RLIMIT_DATA value to figure out if we're allowed to assign
new @start_brk, @brk, @start_data, @end_data from mm_struct) it's been
commited that RLIMIT_DATA in a form it's implemented now doesn't do
anything useful because most of user-space libraries use mmap() syscall
for dynamic memory allocations.

Linus suggested to convert RLIMIT_DATA rlimit into something suitable
for anonymous memory accounting.  But in this patch we go further, and
the changes are bundled together as:

 * keep vma counting if CONFIG_PROC_FS=n, will be used for limits
 * replace mm->shared_vm with better defined mm->data_vm
 * account anonymous executable areas as executable
 * account file-backed growsdown/up areas as stack
 * drop struct file* argument from vm_stat_account
 * enforce RLIMIT_DATA for size of data areas

This way code looks cleaner: now code/stack/data classification depends
only on vm_flags state:

 VM_EXEC & ~VM_WRITE            -> code  (VmExe + VmLib in proc)
 VM_GROWSUP | VM_GROWSDOWN      -> stack (VmStk)
 VM_WRITE & ~VM_SHARED & !stack -> data  (VmData)

The rest (VmSize - VmData - VmStk - VmExe - VmLib) could be called
"shared", but that might be strange beast like readonly-private or VM_IO
area.

 - RLIMIT_AS            limits whole address space "VmSize"
 - RLIMIT_STACK         limits stack "VmStk" (but each vma individually)
 - RLIMIT_DATA          now limits "VmData"
Signed-off-by: NKonstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: NCyrill Gorcunov <gorcunov@openvz.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Kees Cook <keescook@google.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      84638335
  31. 05 1月, 2016 1 次提交
    • T
      x86/mm/pat: Add untrack_pfn_moved for mremap · d9fe4fab
      由 Toshi Kani 提交于 
      mremap() with MREMAP_FIXED on a VM_PFNMAP range causes the following
WARN_ON_ONCE() message in untrack_pfn().

  WARNING: CPU: 1 PID: 3493 at arch/x86/mm/pat.c:985 untrack_pfn+0xbd/0xd0()
  Call Trace:
  [<ffffffff817729ea>] dump_stack+0x45/0x57
  [<ffffffff8109e4b6>] warn_slowpath_common+0x86/0xc0
  [<ffffffff8109e5ea>] warn_slowpath_null+0x1a/0x20
  [<ffffffff8106a88d>] untrack_pfn+0xbd/0xd0
  [<ffffffff811d2d5e>] unmap_single_vma+0x80e/0x860
  [<ffffffff811d3725>] unmap_vmas+0x55/0xb0
  [<ffffffff811d916c>] unmap_region+0xac/0x120
  [<ffffffff811db86a>] do_munmap+0x28a/0x460
  [<ffffffff811dec33>] move_vma+0x1b3/0x2e0
  [<ffffffff811df113>] SyS_mremap+0x3b3/0x510
  [<ffffffff817793ee>] entry_SYSCALL_64_fastpath+0x12/0x71

MREMAP_FIXED moves a pfnmap from old vma to new vma.  untrack_pfn() is
called with the old vma after its pfnmap page table has been removed,
which causes follow_phys() to fail.  The new vma has a new pfnmap to
the same pfn & cache type with VM_PAT set.  Therefore, we only need to
clear VM_PAT from the old vma in this case.

Add untrack_pfn_moved(), which clears VM_PAT from a given old vma.
move_vma() is changed to call this function with the old vma when
VM_PFNMAP is set.  move_vma() then calls do_munmap(), and untrack_pfn()
is a no-op since VM_PAT is cleared.
Reported-by: NStas Sergeev <stsp@list.ru>
Signed-off-by: NToshi Kani <toshi.kani@hpe.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/1450832064-10093-2-git-send-email-toshi.kani@hpe.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
      d9fe4fab
  33. 06 11月, 2015 1 次提交
  35. 05 9月, 2015 5 次提交
  37. 25 6月, 2015 1 次提交
    • L
      mm: new arch_remap() hook · 4abad2ca
      由 Laurent Dufour 提交于 
      Some architectures would like to be triggered when a memory area is moved
through the mremap system call.

This patch introduces a new arch_remap() mm hook which is placed in the
path of mremap, and is called before the old area is unmapped (and the
arch_unmap() hook is called).
Signed-off-by: NLaurent Dufour <ldufour@linux.vnet.ibm.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      4abad2ca
  39. 16 4月, 2015 2 次提交
  41. 07 4月, 2015 1 次提交
    • A
      fix mremap() vs. ioctx_kill() race · b2edffdd
      由 Al Viro 提交于 
      teach ->mremap() method to return an error and have it fail for
aio mappings in process of being killed

Note that in case of ->mremap() failure we need to undo move_page_tables()
we'd already done; we could call ->mremap() first, but then the failure of
move_page_tables() would require undoing whatever _successful_ ->mremap()
has done, which would be a lot more headache in general.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      b2edffdd
  43. 11 2月, 2015 1 次提交
  45. 14 12月, 2014 3 次提交
  47. 10 10月, 2014 2 次提交
  49. 11 5月, 2014 1 次提交
  51. 17 10月, 2013 1 次提交
  53. 12 9月, 2013 1 次提交