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> [ luis: backported to 3.16: - use VM_BUG_ON() instead of VM_BUG_ON_VMA() ] Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
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@ -6,7 +6,8 @@
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#ifdef CONFIG_TRANSPARENT_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 int __khugepaged_enter(struct mm_struct *mm);
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extern void __khugepaged_exit(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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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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#define khugepaged_enabled() \
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(transparent_hugepage_flags & \
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(transparent_hugepage_flags & \
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@ -35,13 +36,13 @@ static inline void khugepaged_exit(struct mm_struct *mm)
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__khugepaged_exit(mm);
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__khugepaged_exit(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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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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{
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if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags))
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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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if ((khugepaged_always() ||
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(khugepaged_req_madv() &&
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(khugepaged_req_madv() && (vm_flags & VM_HUGEPAGE))) &&
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vma->vm_flags & VM_HUGEPAGE)) &&
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!(vm_flags & VM_NOHUGEPAGE))
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!(vma->vm_flags & VM_NOHUGEPAGE))
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if (__khugepaged_enter(vma->vm_mm))
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if (__khugepaged_enter(vma->vm_mm))
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return -ENOMEM;
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return -ENOMEM;
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return 0;
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return 0;
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@ -54,11 +55,13 @@ static inline int khugepaged_fork(struct mm_struct *mm, struct mm_struct *oldmm)
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static inline void khugepaged_exit(struct mm_struct *mm)
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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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}
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}
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static inline int khugepaged_enter(struct vm_area_struct *vma)
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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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{
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return 0;
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return 0;
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}
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}
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static inline int khugepaged_enter_vma_merge(struct vm_area_struct *vma)
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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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{
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return 0;
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return 0;
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}
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}
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@ -788,7 +788,7 @@ int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
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if (haddr >= vma->vm_start && haddr + HPAGE_PMD_SIZE <= vma->vm_end) {
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if (haddr >= vma->vm_start && haddr + HPAGE_PMD_SIZE <= vma->vm_end) {
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if (unlikely(anon_vma_prepare(vma)))
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if (unlikely(anon_vma_prepare(vma)))
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return VM_FAULT_OOM;
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return VM_FAULT_OOM;
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if (unlikely(khugepaged_enter(vma)))
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if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
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return VM_FAULT_OOM;
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return VM_FAULT_OOM;
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if (!(flags & FAULT_FLAG_WRITE) &&
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if (!(flags & FAULT_FLAG_WRITE) &&
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transparent_hugepage_use_zero_page()) {
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transparent_hugepage_use_zero_page()) {
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@ -1925,7 +1925,7 @@ int hugepage_madvise(struct vm_area_struct *vma,
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* register it here without waiting a page fault that
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* register it here without waiting a page fault that
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* may not happen any time soon.
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* may not happen any time soon.
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*/
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*/
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if (unlikely(khugepaged_enter_vma_merge(vma)))
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if (unlikely(khugepaged_enter_vma_merge(vma, *vm_flags)))
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return -ENOMEM;
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return -ENOMEM;
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break;
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break;
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case MADV_NOHUGEPAGE:
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case MADV_NOHUGEPAGE:
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@ -2026,7 +2026,8 @@ int __khugepaged_enter(struct mm_struct *mm)
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return 0;
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return 0;
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}
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}
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int khugepaged_enter_vma_merge(struct vm_area_struct *vma)
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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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{
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unsigned long hstart, hend;
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unsigned long hstart, hend;
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if (!vma->anon_vma)
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if (!vma->anon_vma)
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@ -2038,11 +2039,11 @@ int khugepaged_enter_vma_merge(struct vm_area_struct *vma)
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if (vma->vm_ops)
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if (vma->vm_ops)
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/* khugepaged not yet working on file or special mappings */
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/* khugepaged not yet working on file or special mappings */
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return 0;
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return 0;
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VM_BUG_ON(vma->vm_flags & VM_NO_THP);
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VM_BUG_ON(vm_flags & VM_NO_THP);
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hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
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hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
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hend = vma->vm_end & HPAGE_PMD_MASK;
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hend = vma->vm_end & HPAGE_PMD_MASK;
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if (hstart < hend)
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if (hstart < hend)
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return khugepaged_enter(vma);
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return khugepaged_enter(vma, vm_flags);
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return 0;
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return 0;
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}
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}
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@ -1076,7 +1076,7 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
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end, prev->vm_pgoff, NULL);
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end, prev->vm_pgoff, NULL);
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if (err)
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if (err)
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return NULL;
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return NULL;
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khugepaged_enter_vma_merge(prev);
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khugepaged_enter_vma_merge(prev, vm_flags);
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return prev;
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return prev;
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}
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}
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@ -1095,7 +1095,7 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
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next->vm_pgoff - pglen, NULL);
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next->vm_pgoff - pglen, NULL);
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if (err)
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if (err)
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return NULL;
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return NULL;
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khugepaged_enter_vma_merge(area);
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khugepaged_enter_vma_merge(area, vm_flags);
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return area;
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return area;
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}
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}
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@ -2260,7 +2260,7 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
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}
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}
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}
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}
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vma_unlock_anon_vma(vma);
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vma_unlock_anon_vma(vma);
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khugepaged_enter_vma_merge(vma);
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khugepaged_enter_vma_merge(vma, vma->vm_flags);
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validate_mm(vma->vm_mm);
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validate_mm(vma->vm_mm);
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return error;
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return error;
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}
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}
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@ -2339,7 +2339,7 @@ int expand_downwards(struct vm_area_struct *vma,
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}
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}
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}
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}
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vma_unlock_anon_vma(vma);
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vma_unlock_anon_vma(vma);
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khugepaged_enter_vma_merge(vma);
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khugepaged_enter_vma_merge(vma, vma->vm_flags);
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validate_mm(vma->vm_mm);
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validate_mm(vma->vm_mm);
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return error;
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return error;
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}
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}
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