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 Subject: khugepaged: recheck pmd after mmap_sem re-acquired Vlastimil noted[1] that pmd can be no longer valid after we drop mmap_sem.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 @@ -2433,6 +2433,9 @@ 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); @@ -2518,6 +2521,9 @@ 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); _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
