From 50f8b92f21d23789bd4ada593e8ddc56cc4f79fe Mon Sep 17 00:00:00 2001 From: Song Liu Date: Fri, 17 Aug 2018 15:47:00 -0700 Subject: [PATCH] mm: thp: pass correct vm_flags to hugepage_vma_check() khugepaged_enter_vma_merge() passes a stale vma->vm_flags to hugepage_vma_check(). The argument vm_flags contains the latest value. Therefore, it is necessary to pass this vm_flags into hugepage_vma_check(). With this bug, madvise(MADV_HUGEPAGE) for mmap files in shmem fails to put memory in huge pages. Here is an example of failed madvise(): /* mount /dev/shm with huge=advise: * mount -o remount,huge=advise /dev/shm */ /* create file /dev/shm/huge */ #define HUGE_FILE "/dev/shm/huge" fd = open(HUGE_FILE, O_RDONLY); ptr = mmap(NULL, FILE_SIZE, PROT_READ, MAP_PRIVATE, fd, 0); ret = madvise(ptr, FILE_SIZE, MADV_HUGEPAGE); madvise() will return 0, but this memory region is never put in huge page (check from /proc/meminfo: ShmemHugePages). Link: http://lkml.kernel.org/r/20180629181752.792831-1-songliubraving@fb.com Fixes: 02b75dc8160d ("mm: thp: register mm for khugepaged when merging vma for shmem") Signed-off-by: Song Liu Reviewed-by: Rik van Riel Reviewed-by: Yang Shi Cc: Kirill A. Shutemov Cc: Hugh Dickins Cc: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/khugepaged.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 79d55e1..961cbe9 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -397,10 +397,11 @@ static inline int khugepaged_test_exit(struct mm_struct *mm) return atomic_read(&mm->mm_users) == 0; } -static bool hugepage_vma_check(struct vm_area_struct *vma) +static bool hugepage_vma_check(struct vm_area_struct *vma, + unsigned long vm_flags) { - if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || - (vma->vm_flags & VM_NOHUGEPAGE) || + if ((!(vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || + (vm_flags & VM_NOHUGEPAGE) || test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) return false; if (shmem_file(vma->vm_file)) { @@ -413,7 +414,7 @@ static bool hugepage_vma_check(struct vm_area_struct *vma) return false; if (is_vma_temporary_stack(vma)) return false; - return !(vma->vm_flags & VM_NO_KHUGEPAGED); + return !(vm_flags & VM_NO_KHUGEPAGED); } int __khugepaged_enter(struct mm_struct *mm) @@ -458,7 +459,7 @@ int khugepaged_enter_vma_merge(struct vm_area_struct *vma, * khugepaged does not yet work on non-shmem files or special * mappings. And file-private shmem THP is not supported. */ - if (!hugepage_vma_check(vma)) + if (!hugepage_vma_check(vma, vm_flags)) return 0; hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; @@ -861,7 +862,7 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, hend = vma->vm_end & HPAGE_PMD_MASK; if (address < hstart || address + HPAGE_PMD_SIZE > hend) return SCAN_ADDRESS_RANGE; - if (!hugepage_vma_check(vma)) + if (!hugepage_vma_check(vma, vma->vm_flags)) return SCAN_VMA_CHECK; return 0; } @@ -1695,7 +1696,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, progress++; break; } - if (!hugepage_vma_check(vma)) { + if (!hugepage_vma_check(vma, vma->vm_flags)) { skip: progress++; continue; -- 2.7.4