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authorDavid Rientjes <rientjes@google.com>2014-10-29 14:50:31 -0700
committerBen Hutchings <ben@decadent.org.uk>2014-12-14 16:23:52 +0000
commit37e867c16ad3f6ac7e117d87f55e3863cb2854a2 (patch)
tree7f1905ecf991639906e0459205afabfeb1a5043d /include
parente0fb1fad0739d6c56264ebeaf7fc7ae61b085632 (diff)
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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 <rientjes@google.com> Reported-by: Suleiman Souhlal <suleiman@google.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> [bwh: Backported to 3.2: adjust context, indentation] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'include')
-rw-r--r--include/linux/khugepaged.h17
1 files changed, 10 insertions, 7 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;
}