From: Kirill A. Shutemov Date: Tue, 26 Jul 2016 22:25:12 +0000 (-0700) Subject: khugepaged: recheck pmd after mmap_sem re-acquired X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=1f52e67e5e7f48424059f8168e3a65bddc80ad97;p=openwrt%2Fstaging%2Fblogic.git khugepaged: recheck pmd after mmap_sem re-acquired Vlastimil noted[1] that pmd can be no longer valid after we drop mmap_sem.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@suse.cz Link: http://lkml.kernel.org/r/1466021202-61880-6-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 1841e0ceac23..1a90f55d930f 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2433,6 +2433,9 @@ static bool __collapse_huge_page_swapin(struct mm_struct *mm, /* 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_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);