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5e93a23b3f
commit 6d50e60cd2 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>
[lizf: Backported to 3.4: adjust context]
Signed-off-by: Zefan Li <lizefan@huawei.com>
70 lines
2 KiB
C
70 lines
2 KiB
C
#ifndef _LINUX_KHUGEPAGED_H
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#define _LINUX_KHUGEPAGED_H
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#include <linux/sched.h> /* MMF_VM_HUGEPAGE */
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#ifdef CONFIG_TRANSPARENT_HUGEPAGE
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extern int __khugepaged_enter(struct mm_struct *mm);
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extern void __khugepaged_exit(struct mm_struct *mm);
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extern int khugepaged_enter_vma_merge(struct vm_area_struct *vma,
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unsigned long vm_flags);
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#define khugepaged_enabled() \
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(transparent_hugepage_flags & \
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((1<<TRANSPARENT_HUGEPAGE_FLAG) | \
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(1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)))
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#define khugepaged_always() \
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(transparent_hugepage_flags & \
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(1<<TRANSPARENT_HUGEPAGE_FLAG))
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#define khugepaged_req_madv() \
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(transparent_hugepage_flags & \
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(1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG))
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#define khugepaged_defrag() \
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(transparent_hugepage_flags & \
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(1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG))
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static inline int khugepaged_fork(struct mm_struct *mm, struct mm_struct *oldmm)
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{
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if (test_bit(MMF_VM_HUGEPAGE, &oldmm->flags))
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return __khugepaged_enter(mm);
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return 0;
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}
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static inline void khugepaged_exit(struct mm_struct *mm)
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{
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if (test_bit(MMF_VM_HUGEPAGE, &mm->flags))
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__khugepaged_exit(mm);
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}
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static inline int khugepaged_enter(struct vm_area_struct *vma,
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unsigned long vm_flags)
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{
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if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags))
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if ((khugepaged_always() ||
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(khugepaged_req_madv() && (vm_flags & VM_HUGEPAGE))) &&
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!(vm_flags & VM_NOHUGEPAGE))
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if (__khugepaged_enter(vma->vm_mm))
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return -ENOMEM;
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return 0;
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}
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#else /* CONFIG_TRANSPARENT_HUGEPAGE */
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static inline int khugepaged_fork(struct mm_struct *mm, struct mm_struct *oldmm)
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{
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return 0;
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}
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static inline void khugepaged_exit(struct mm_struct *mm)
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{
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}
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static inline int khugepaged_enter(struct vm_area_struct *vma,
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unsigned long vm_flags)
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{
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return 0;
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}
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static inline int khugepaged_enter_vma_merge(struct vm_area_struct *vma,
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unsigned long vm_flags)
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{
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return 0;
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}
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#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
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#endif /* _LINUX_KHUGEPAGED_H */
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