From 8d55e44b36dbc85fc8c8f60c891f40a51b7f359c Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Wed, 29 Oct 2014 14:50:31 -0700 Subject: [PATCH] mm, thp: fix collapsing of hugepages on madvise commit 6d50e60cd2edb5a57154db5a6f64eef5aa59b751 upstream. If an anonymous mapping is not allowed to fault thp memory and then madvise(MADV_HUGEPAGE) is used after fault, khugepaged will never collapse this memory into thp memory. This occurs because the madvise(2) handler for thp, hugepage_madvise(), clears VM_NOHUGEPAGE on the stack and it isn't stored in vma->vm_flags until the final action of madvise_behavior(). This causes the khugepaged_enter_vma_merge() to be a no-op in hugepage_madvise() when the vma had previously had VM_NOHUGEPAGE set. Fix this by passing the correct vma flags to the khugepaged mm slot handler. There's no chance khugepaged can run on this vma until after madvise_behavior() returns since we hold mm->mmap_sem. It would be possible to clear VM_NOHUGEPAGE directly from vma->vm_flags in hugepage_advise(), but I didn't want to introduce special case behavior into madvise_behavior(). I think it's best to just let it always set vma->vm_flags itself. Signed-off-by: David Rientjes Reported-by: Suleiman Souhlal Cc: "Kirill A. Shutemov" Cc: Andrea Arcangeli Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds [ luis: backported to 3.16: - use VM_BUG_ON() instead of VM_BUG_ON_VMA() ] Signed-off-by: Luis Henriques --- include/linux/khugepaged.h | 17 ++++++++++------- mm/huge_memory.c | 11 ++++++----- mm/mmap.c | 8 ++++---- 3 files changed, 20 insertions(+), 16 deletions(-) diff --git a/include/linux/khugepaged.h b/include/linux/khugepaged.h index 6b394f0b5148..eeb307985715 100644 --- a/include/linux/khugepaged.h +++ b/include/linux/khugepaged.h @@ -6,7 +6,8 @@ #ifdef CONFIG_TRANSPARENT_HUGEPAGE extern int __khugepaged_enter(struct mm_struct *mm); extern void __khugepaged_exit(struct mm_struct *mm); -extern int khugepaged_enter_vma_merge(struct vm_area_struct *vma); +extern int khugepaged_enter_vma_merge(struct vm_area_struct *vma, + unsigned long vm_flags); #define khugepaged_enabled() \ (transparent_hugepage_flags & \ @@ -35,13 +36,13 @@ static inline void khugepaged_exit(struct mm_struct *mm) __khugepaged_exit(mm); } -static inline int khugepaged_enter(struct vm_area_struct *vma) +static inline int khugepaged_enter(struct vm_area_struct *vma, + unsigned long vm_flags) { if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags)) if ((khugepaged_always() || - (khugepaged_req_madv() && - vma->vm_flags & VM_HUGEPAGE)) && - !(vma->vm_flags & VM_NOHUGEPAGE)) + (khugepaged_req_madv() && (vm_flags & VM_HUGEPAGE))) && + !(vm_flags & VM_NOHUGEPAGE)) if (__khugepaged_enter(vma->vm_mm)) return -ENOMEM; return 0; @@ -54,11 +55,13 @@ static inline int khugepaged_fork(struct mm_struct *mm, struct mm_struct *oldmm) static inline void khugepaged_exit(struct mm_struct *mm) { } -static inline int khugepaged_enter(struct vm_area_struct *vma) +static inline int khugepaged_enter(struct vm_area_struct *vma, + unsigned long vm_flags) { return 0; } -static inline int khugepaged_enter_vma_merge(struct vm_area_struct *vma) +static inline int khugepaged_enter_vma_merge(struct vm_area_struct *vma, + unsigned long vm_flags) { return 0; } diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 985328953054..9892ab0bf2b2 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -788,7 +788,7 @@ int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, if (haddr >= vma->vm_start && haddr + HPAGE_PMD_SIZE <= vma->vm_end) { if (unlikely(anon_vma_prepare(vma))) return VM_FAULT_OOM; - if (unlikely(khugepaged_enter(vma))) + if (unlikely(khugepaged_enter(vma, vma->vm_flags))) return VM_FAULT_OOM; if (!(flags & FAULT_FLAG_WRITE) && transparent_hugepage_use_zero_page()) { @@ -1925,7 +1925,7 @@ int hugepage_madvise(struct vm_area_struct *vma, * register it here without waiting a page fault that * may not happen any time soon. */ - if (unlikely(khugepaged_enter_vma_merge(vma))) + if (unlikely(khugepaged_enter_vma_merge(vma, *vm_flags))) return -ENOMEM; break; case MADV_NOHUGEPAGE: @@ -2026,7 +2026,8 @@ int __khugepaged_enter(struct mm_struct *mm) return 0; } -int khugepaged_enter_vma_merge(struct vm_area_struct *vma) +int khugepaged_enter_vma_merge(struct vm_area_struct *vma, + unsigned long vm_flags) { unsigned long hstart, hend; if (!vma->anon_vma) @@ -2038,11 +2039,11 @@ int khugepaged_enter_vma_merge(struct vm_area_struct *vma) if (vma->vm_ops) /* khugepaged not yet working on file or special mappings */ return 0; - VM_BUG_ON(vma->vm_flags & VM_NO_THP); + VM_BUG_ON(vm_flags & VM_NO_THP); hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; hend = vma->vm_end & HPAGE_PMD_MASK; if (hstart < hend) - return khugepaged_enter(vma); + return khugepaged_enter(vma, vm_flags); return 0; } diff --git a/mm/mmap.c b/mm/mmap.c index 4d7171989f2d..691b0a870c96 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1076,7 +1076,7 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm, end, prev->vm_pgoff, NULL); if (err) return NULL; - khugepaged_enter_vma_merge(prev); + khugepaged_enter_vma_merge(prev, vm_flags); return prev; } @@ -1095,7 +1095,7 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm, next->vm_pgoff - pglen, NULL); if (err) return NULL; - khugepaged_enter_vma_merge(area); + khugepaged_enter_vma_merge(area, vm_flags); return area; } @@ -2260,7 +2260,7 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address) } } vma_unlock_anon_vma(vma); - khugepaged_enter_vma_merge(vma); + khugepaged_enter_vma_merge(vma, vma->vm_flags); validate_mm(vma->vm_mm); return error; } @@ -2339,7 +2339,7 @@ int expand_downwards(struct vm_area_struct *vma, } } vma_unlock_anon_vma(vma); - khugepaged_enter_vma_merge(vma); + khugepaged_enter_vma_merge(vma, vma->vm_flags); validate_mm(vma->vm_mm); return error; }