linux.git/mm/huge_memory.c, branch v4.16

mm, thp: do not cause memcg oom for thp

2018-03-23T00:07:02+00:00

Commit 2516035499b9 ("mm, thp: remove __GFP_NORETRY from khugepaged and
madvised allocations") changed the page allocator to no longer detect
thp allocations based on __GFP_NORETRY.

It did not, however, modify the mem cgroup try_charge() path to avoid
oom kill for either khugepaged collapsing or thp faulting.  It is never
expected to oom kill a process to allocate a hugepage for thp; reclaim
is governed by the thp defrag mode and MADV_HUGEPAGE, but allocations
(and charging) should fallback instead of oom killing processes.

Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1803191409420.124411@chino.kir.corp.google.com
Fixes: 2516035499b9 ("mm, thp: remove __GFP_NORETRY from khugepaged and madvised allocations")
Signed-off-by: David Rientjes 
Cc: "Kirill A. Shutemov" 
Cc: Michal Hocko 
Cc: Vlastimil Babka 
Cc: Johannes Weiner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/thp: do not wait for lock_page() in deferred_split_scan()

2018-03-23T00:07:01+00:00

deferred_split_scan() gets called from reclaim path.  Waiting for page
lock may lead to deadlock there.

Replace lock_page() with trylock_page() and skip the page if we failed
to lock it.  We will get to the page on the next scan.

Link: http://lkml.kernel.org/r/20180315150747.31945-1-kirill.shutemov@linux.intel.com
Fixes: 9a982250f773 ("thp: introduce deferred_split_huge_page()")
Signed-off-by: Kirill A. Shutemov 
Acked-by: Michal Hocko 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/thp: remove pmd_huge_split_prepare()

2018-02-01T01:18:38+00:00

Instead of marking the pmd ready for split, invalidate the pmd.  This
should take care of powerpc requirement.  Only side effect is that we
mark the pmd invalid early.  This can result in us blocking access to
the page a bit longer if we race against a thp split.

[kirill.shutemov@linux.intel.com: rebased, dirty THP once]
Link: http://lkml.kernel.org/r/20171213105756.69879-13-kirill.shutemov@linux.intel.com
Signed-off-by: Aneesh Kumar K.V 
Signed-off-by: Kirill A. Shutemov 
Cc: Andrea Arcangeli 
Cc: Catalin Marinas 
Cc: David Daney 
Cc: David Miller 
Cc: H. Peter Anvin 
Cc: Hugh Dickins 
Cc: Ingo Molnar 
Cc: Martin Schwidefsky 
Cc: Michal Hocko 
Cc: Nitin Gupta 
Cc: Ralf Baechle 
Cc: Thomas Gleixner 
Cc: Vineet Gupta 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: use updated pmdp_invalidate() interface to track dirty/accessed bits

2018-02-01T01:18:38+00:00

Use the modifed pmdp_invalidate() that returns the previous value of pmd
to transfer dirty and accessed bits.

Link: http://lkml.kernel.org/r/20171213105756.69879-12-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov 
Cc: Andrea Arcangeli 
Cc: Aneesh Kumar K.V 
Cc: Catalin Marinas 
Cc: David Daney 
Cc: David Miller 
Cc: H. Peter Anvin 
Cc: Hugh Dickins 
Cc: Ingo Molnar 
Cc: Martin Schwidefsky 
Cc: Michal Hocko 
Cc: Nitin Gupta 
Cc: Ralf Baechle 
Cc: Thomas Gleixner 
Cc: Vineet Gupta 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/huge_memory.c: fix comment in __split_huge_pmd_locked

2018-02-01T01:18:37+00:00

pmd_trans_splitting() was removed after THP refcounting redesign,
therefore related comment should be updated.

Link: http://lkml.kernel.org/r/1512625745-59451-1-git-send-email-xieyisheng1@huawei.com
Signed-off-by: Yisheng Xie 
Acked-by: Kirill A. Shutemov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Revert "mm: replace p??_write with pte_access_permitted in fault + gup paths"

2017-12-16T02:53:22+00:00

This reverts commits 5c9d2d5c269c, c7da82b894e9, and e7fe7b5cae90.

We'll probably need to revisit this, but basically we should not
complicate the get_user_pages_fast() case, and checking the actual page
table protection key bits will require more care anyway, since the
protection keys depend on the exact state of the VM in question.

Particularly when doing a "remote" page lookup (ie in somebody elses VM,
not your own), you need to be much more careful than this was.  Dave
Hansen says:

 "So, the underlying bug here is that we now a get_user_pages_remote()
  and then go ahead and do the p*_access_permitted() checks against the
  current PKRU. This was introduced recently with the addition of the
  new p??_access_permitted() calls.

  We have checks in the VMA path for the "remote" gups and we avoid
  consulting PKRU for them. This got missed in the pkeys selftests
  because I did a ptrace read, but not a *write*. I also didn't
  explicitly test it against something where a COW needed to be done"

It's also not entirely clear that it makes sense to check the protection
key bits at this level at all.  But one possible eventual solution is to
make the get_user_pages_fast() case just abort if it sees protection key
bits set, which makes us fall back to the regular get_user_pages() case,
which then has a vma and can do the check there if we want to.

We'll see.

Somewhat related to this all: what we _do_ want to do some day is to
check the PAGE_USER bit - it should obviously always be set for user
pages, but it would be a good check to have back.  Because we have no
generic way to test for it, we lost it as part of moving over from the
architecture-specific x86 GUP implementation to the generic one in
commit e585513b76f7 ("x86/mm/gup: Switch GUP to the generic
get_user_page_fast() implementation").

Cc: Peter Zijlstra 
Cc: Dan Williams 
Cc: Dave Hansen 
Cc: Kirill A. Shutemov 
Cc: "Jérôme Glisse" 
Cc: Andrew Morton 
Cc: Al Viro 
Signed-off-by: Linus Torvalds

Merge branch 'akpm' (patches from Andrew)

2017-11-30T03:12:44+00:00

Mergr misc fixes from Andrew Morton:
 "28 fixes"

* emailed patches from Andrew Morton : (28 commits)
  fs/hugetlbfs/inode.c: change put_page/unlock_page order in hugetlbfs_fallocate()
  mm/hugetlb: fix NULL-pointer dereference on 5-level paging machine
  autofs: revert "autofs: fix AT_NO_AUTOMOUNT not being honored"
  autofs: revert "autofs: take more care to not update last_used on path walk"
  fs/fat/inode.c: fix sb_rdonly() change
  mm, memcg: fix mem_cgroup_swapout() for THPs
  mm: migrate: fix an incorrect call of prep_transhuge_page()
  kmemleak: add scheduling point to kmemleak_scan()
  scripts/bloat-o-meter: don't fail with division by 0
  fs/mbcache.c: make count_objects() more robust
  Revert "mm/page-writeback.c: print a warning if the vm dirtiness settings are illogical"
  mm/madvise.c: fix madvise() infinite loop under special circumstances
  exec: avoid RLIMIT_STACK races with prlimit()
  IB/core: disable memory registration of filesystem-dax vmas
  v4l2: disable filesystem-dax mapping support
  mm: fail get_vaddr_frames() for filesystem-dax mappings
  mm: introduce get_user_pages_longterm
  device-dax: implement ->split() to catch invalid munmap attempts
  mm, hugetlbfs: introduce ->split() to vm_operations_struct
  scripts/faddr2line: extend usage on generic arch
  ...

mm: replace pmd_write with pmd_access_permitted in fault + gup paths

2017-11-30T02:40:42+00:00

The 'access_permitted' helper is used in the gup-fast path and goes
beyond the simple _PAGE_RW check to also:

 - validate that the mapping is writable from a protection keys
   standpoint

 - validate that the pte has _PAGE_USER set since all fault paths where
   pmd_write is must be referencing user-memory.

Link: http://lkml.kernel.org/r/151043111049.2842.15241454964150083466.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams 
Cc: Dave Hansen 
Cc: Kirill A. Shutemov 
Cc: "Jérôme Glisse" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: replace pud_write with pud_access_permitted in fault + gup paths

2017-11-30T02:40:42+00:00

The 'access_permitted' helper is used in the gup-fast path and goes
beyond the simple _PAGE_RW check to also:

 - validate that the mapping is writable from a protection keys
   standpoint

 - validate that the pte has _PAGE_USER set since all fault paths where
   pud_write is must be referencing user-memory.

[dan.j.williams@intel.com: fix powerpc compile error]
  Link: http://lkml.kernel.org/r/151129127237.37405.16073414520854722485.stgit@dwillia2-desk3.amr.corp.intel.com
Link: http://lkml.kernel.org/r/151043110453.2842.2166049702068628177.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams 
Cc: Dave Hansen 
Cc: "David S. Miller" 
Cc: Kirill A. Shutemov 
Cc: Martin Schwidefsky 
Cc: Heiko Carstens 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Revert "mm, thp: Do not make pmd/pud dirty without a reason"

2017-11-29T17:01:01+00:00

This reverts commit 152e93af3cfe2d29d8136cc0a02a8612507136ee.

It was a nice cleanup in theory, but as Nicolai Stange points out, we do
need to make the page dirty for the copy-on-write case even when we
didn't end up making it writable, since the dirty bit is what we use to
check that we've gone through a COW cycle.

Reported-by: Michal Hocko 
Acked-by: Kirill A. Shutemov 
Signed-off-by: Linus Torvalds