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| author | Mike Kravetz <mike.kravetz@oracle.com> | 2019-01-08 15:23:32 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-01-08 17:15:11 -0800 |
| commit | e7c58097793ef15d58fadf190ee58738fbf447cd (patch) | |
| tree | 7dd04f50d4daadba4f8f3550a6d39d1a0ac2cda7 /mm | |
| parent | 8ab88c7169b7fba98812ead6524b9d05bc76cf00 (diff) | |
| download | linux-0-day-e7c58097793ef15d58fadf190ee58738fbf447cd.tar.gz linux-0-day-e7c58097793ef15d58fadf190ee58738fbf447cd.tar.xz | |
hugetlbfs: revert "Use i_mmap_rwsem to fix page fault/truncate race"
This reverts c86aa7bbfd5568ba8a82d3635d8f7b8a8e06fe54
The reverted commit caused ABBA deadlocks when file migration raced with
file eviction for specific hugetlbfs files. This was discovered with a
modified version of the LTP move_pages12 test.
The purpose of the reverted patch was to close a long existing race
between hugetlbfs file truncation and page faults. After more analysis
of the patch and impacted code, it was determined that i_mmap_rwsem can
not be used for all required synchronization. Therefore, revert this
patch while working an another approach to the underlying issue.
Link: http://lkml.kernel.org/r/20190103235452.29335-1-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reported-by: Jan Stancek <jstancek@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Prakash Sangappa <prakash.sangappa@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/hugetlb.c | 21 |
1 files changed, 11 insertions, 10 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 7450888109651..aedc1b183cf93 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -3755,16 +3755,16 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm, } /* - * We can not race with truncation due to holding i_mmap_rwsem. - * Check once here for faults beyond end of file. + * Use page lock to guard against racing truncation + * before we get page_table_lock. */ - size = i_size_read(mapping->host) >> huge_page_shift(h); - if (idx >= size) - goto out; - retry: page = find_lock_page(mapping, idx); if (!page) { + size = i_size_read(mapping->host) >> huge_page_shift(h); + if (idx >= size) + goto out; + /* * Check for page in userfault range */ @@ -3854,6 +3854,9 @@ retry: } ptl = huge_pte_lock(h, mm, ptep); + size = i_size_read(mapping->host) >> huge_page_shift(h); + if (idx >= size) + goto backout; ret = 0; if (!huge_pte_none(huge_ptep_get(ptep))) @@ -3956,10 +3959,8 @@ vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, /* * Acquire i_mmap_rwsem before calling huge_pte_alloc and hold - * until finished with ptep. This serves two purposes: - * 1) It prevents huge_pmd_unshare from being called elsewhere - * and making the ptep no longer valid. - * 2) It synchronizes us with file truncation. + * until finished with ptep. This prevents huge_pmd_unshare from + * being called elsewhere and making the ptep no longer valid. * * ptep could have already be assigned via huge_pte_offset. That * is OK, as huge_pte_alloc will return the same value unless |