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* [PATCH v3 0/2] hugetlbfs: use i_mmap_rwsem for better synchronization
@ 2018-12-22 22:30 Mike Kravetz
  2018-12-22 22:30 ` [PATCH v3 1/2] hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization Mike Kravetz
                   ` (2 more replies)
  0 siblings, 3 replies; 7+ messages in thread
From: Mike Kravetz @ 2018-12-22 22:30 UTC (permalink / raw)
  To: linux-mm, linux-kernel
  Cc: Michal Hocko, Hugh Dickins, Naoya Horiguchi, Aneesh Kumar K . V,
	Andrea Arcangeli, Kirill A . Shutemov, Davidlohr Bueso,
	Prakash Sangappa, Andrew Morton, Mike Kravetz

There are two primary issues addressed here:
1) For shared pmds, huge PTE pointers returned by huge_pte_alloc can become
   invalid via a call to huge_pmd_unshare by another thread.
2) hugetlbfs page faults can race with truncation causing invalid global
   reserve counts and state.
Both issues are addressed by expanding the use of i_mmap_rwsem.

These issues have existed for a long time.  They can be recreated with a
test program that causes page fault/truncation races.  For simple mappings,
this results in a negative HugePages_Rsvd count.  If racing with mappings
that contain shared pmds, we can hit "BUG at fs/hugetlbfs/inode.c:444!" or
Oops! as the result of an invalid memory reference.

v2 -> v3
  Incorporated suggestions from Kirill.  Code change to hold i_mmap_rwsem
  for duration of copy in copy_hugetlb_page_range.  Took i_mmap_rwsem in
  hugetlbfs_evict_inode to be consistent with other callers.  Other changes
  were to documentation/comments.
v1 -> v2
  Combined patches 2 and 3 of v1 series as suggested by Aneesh.  No other
  changes were made.
Patches are a follow up to the RFC,
  http://lkml.kernel.org/r/20181024045053.1467-1-mike.kravetz@oracle.com
  Comments made by Naoya were addressed.

Mike Kravetz (2):
  hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization
  hugetlbfs: Use i_mmap_rwsem to fix page fault/truncate race

 fs/hugetlbfs/inode.c | 61 +++++++++++++++-----------------
 mm/hugetlb.c         | 84 +++++++++++++++++++++++++++++++-------------
 mm/memory-failure.c  | 14 +++++++-
 mm/migrate.c         | 13 ++++++-
 mm/rmap.c            |  4 +++
 mm/userfaultfd.c     | 11 ++++--
 6 files changed, 125 insertions(+), 62 deletions(-)

-- 
2.17.2

^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2019-01-02 16:54 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-12-22 22:30 [PATCH v3 0/2] hugetlbfs: use i_mmap_rwsem for better synchronization Mike Kravetz
2018-12-22 22:30 ` [PATCH v3 1/2] hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization Mike Kravetz
2018-12-28 14:26   ` [LKP] [hugetlbfs] 9c83282117: vm-scalability.throughput -4.3% regression kernel test robot
2018-12-28 14:26     ` kernel test robot
2019-01-02 16:54     ` Mike Kravetz
2018-12-22 22:30 ` [PATCH v3 2/2] hugetlbfs: Use i_mmap_rwsem to fix page fault/truncate race Mike Kravetz
2018-12-24 10:13 ` [PATCH v3 0/2] hugetlbfs: use i_mmap_rwsem for better synchronization Kirill A. Shutemov

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