The patch titled
Subject: khugepaged: recheck pmd after mmap_sem re-acquired
has been added to the -mm tree. Its filename is
khugepaged-recheck-pmd-after-mmap_sem-re-acquired.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/khugepaged-recheck-pmd-after-mmap_sem-re-acquired.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/khugepaged-recheck-pmd-after-mmap_sem-re-acquired.patch
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------------------------------------------------------
From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Subject: khugepaged: recheck pmd after mmap_sem re-acquired
Vlastimil noted[1] that pmd can be no longer valid after we drop
mmap_sem. We need recheck it once mmap_sem taken again.
[1] http://lkml.kernel.org/r/12918dcd-a695-c6f4-e06f-69141c5f357f@xxxxxxx
Link: http://lkml.kernel.org/r/1466021202-61880-6-git-send-email-kirill.shutemov@xxxxxxxxxxxxxxx
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 6 ++++++
1 file changed, 6 insertions(+)
diff -puN mm/huge_memory.c~khugepaged-recheck-pmd-after-mmap_sem-re-acquired mm/huge_memory.c
--- a/mm/huge_memory.c~khugepaged-recheck-pmd-after-mmap_sem-re-acquired
+++ a/mm/huge_memory.c
@@ -2438,6 +2438,9 @@ static bool __collapse_huge_page_swapin(
/* vma is no longer available, don't continue to swapin */
if (hugepage_vma_revalidate(mm, address))
return false;
+ /* check if the pmd is still valid */
+ if (mm_find_pmd(mm, address) != pmd)
+ return false;
}
if (ret & VM_FAULT_ERROR) {
trace_mm_collapse_huge_page_swapin(mm, swapped_in, 0);
@@ -2523,6 +2526,9 @@ static void collapse_huge_page(struct mm
result = hugepage_vma_revalidate(mm, address);
if (result)
goto out;
+ /* check if the pmd is still valid */
+ if (mm_find_pmd(mm, address) != pmd)
+ goto out;
anon_vma_lock_write(vma->anon_vma);
_
Patches currently in -mm which might be from kirill.shutemov@xxxxxxxxxxxxxxx are
revert-mm-make-faultaround-produce-old-ptes.patch
revert-mm-disable-fault-around-on-emulated-access-bit-architecture.patch
mm-make-swapin-readahead-to-improve-thp-collapse-rate-fix.patch
mm-make-swapin-readahead-to-improve-thp-collapse-rate-fix-2.patch
mm-make-swapin-readahead-to-improve-thp-collapse-rate-fix-3.patch
mm-thp-make-swapin-readahead-under-down_read-of-mmap_sem-fix.patch
khugepaged-recheck-pmd-after-mmap_sem-re-acquired.patch
thp-mlock-update-unevictable-lrutxt.patch
mm-do-not-pass-mm_struct-into-handle_mm_fault.patch
mm-introduce-fault_env.patch
mm-postpone-page-table-allocation-until-we-have-page-to-map.patch
rmap-support-file-thp.patch
mm-introduce-do_set_pmd.patch
thp-vmstats-add-counters-for-huge-file-pages.patch
thp-support-file-pages-in-zap_huge_pmd.patch
thp-handle-file-pages-in-split_huge_pmd.patch
thp-handle-file-cow-faults.patch
thp-skip-file-huge-pmd-on-copy_huge_pmd.patch
thp-prepare-change_huge_pmd-for-file-thp.patch
thp-run-vma_adjust_trans_huge-outside-i_mmap_rwsem.patch
thp-file-pages-support-for-split_huge_page.patch
thp-mlock-do-not-mlock-pte-mapped-file-huge-pages.patch
vmscan-split-file-huge-pages-before-paging-them-out.patch
page-flags-relax-policy-for-pg_mappedtodisk-and-pg_reclaim.patch
radix-tree-implement-radix_tree_maybe_preload_order.patch
filemap-prepare-find-and-delete-operations-for-huge-pages.patch
truncate-handle-file-thp.patch
mm-rmap-account-shmem-thp-pages.patch
shmem-prepare-huge=-mount-option-and-sysfs-knob.patch
shmem-add-huge-pages-support.patch
shmem-thp-respect-madv_nohugepage-for-file-mappings.patch
thp-extract-khugepaged-from-mm-huge_memoryc.patch
khugepaged-move-up_readmmap_sem-out-of-khugepaged_alloc_page.patch
shmem-make-shmem_inode_info-lock-irq-safe.patch
khugepaged-add-support-of-collapse-for-tmpfs-shmem-pages.patch
thp-introduce-config_transparent_huge_pagecache.patch
shmem-split-huge-pages-beyond-i_size-under-memory-pressure.patch
thp-update-documentation-vm-transhugefilesystems-proctxt.patch
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