![Andrea Arcangeli](/assets/img/avatar_default.png)
The huge_memory.c THP page fault was allowed to run if vm_ops was null (which would succeed for /dev/zero MAP_PRIVATE, as the f_op->mmap wouldn't setup a special vma->vm_ops and it would fallback to regular anonymous memory) but other THP logics weren't fully activated for vmas with vm_file not NULL (/dev/zero has a not NULL vma->vm_file). So this removes the vm_file checks so that /dev/zero also can safely use THP (the other albeit safer approach to fix this bug would have been to prevent the THP initial page fault to run if vm_file was set). After removing the vm_file checks, this also makes huge_memory.c stricter in khugepaged for the DEBUG_VM=y case. It doesn't replace the vm_file check with a is_pfn_mapping check (but it keeps checking for VM_PFNMAP under VM_BUG_ON) because for a is_cow_mapping() mapping VM_PFNMAP should only be allowed to exist before the first page fault, and in turn when vma->anon_vma is null (so preventing khugepaged registration). So I tend to think the previous comment saying if vm_file was set, VM_PFNMAP might have been set and we could still be registered in khugepaged (despite anon_vma was not NULL to be registered in khugepaged) was too paranoid. The is_linear_pfn_mapping check is also I think superfluous (as described by comment) but under DEBUG_VM it is safe to stay. Addresses https://bugzilla.kernel.org/show_bug.cgi?id=33682 Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reported-by: Caspar Zhang <bugs@casparzhang.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Rik van Riel <riel@redhat.com> Cc: <stable@kernel.org> [2.6.38.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
181 lines
5.8 KiB
C
181 lines
5.8 KiB
C
#ifndef _LINUX_HUGE_MM_H
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#define _LINUX_HUGE_MM_H
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extern int do_huge_pmd_anonymous_page(struct mm_struct *mm,
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struct vm_area_struct *vma,
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unsigned long address, pmd_t *pmd,
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unsigned int flags);
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extern int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
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pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
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struct vm_area_struct *vma);
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extern int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
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unsigned long address, pmd_t *pmd,
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pmd_t orig_pmd);
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extern pgtable_t get_pmd_huge_pte(struct mm_struct *mm);
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extern struct page *follow_trans_huge_pmd(struct mm_struct *mm,
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unsigned long addr,
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pmd_t *pmd,
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unsigned int flags);
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extern int zap_huge_pmd(struct mmu_gather *tlb,
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struct vm_area_struct *vma,
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pmd_t *pmd);
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extern int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
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unsigned long addr, unsigned long end,
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unsigned char *vec);
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extern int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
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unsigned long addr, pgprot_t newprot);
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enum transparent_hugepage_flag {
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TRANSPARENT_HUGEPAGE_FLAG,
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TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
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TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
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TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG,
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TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG,
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#ifdef CONFIG_DEBUG_VM
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TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG,
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#endif
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};
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enum page_check_address_pmd_flag {
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PAGE_CHECK_ADDRESS_PMD_FLAG,
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PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG,
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PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG,
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};
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extern pmd_t *page_check_address_pmd(struct page *page,
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struct mm_struct *mm,
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unsigned long address,
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enum page_check_address_pmd_flag flag);
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#ifdef CONFIG_TRANSPARENT_HUGEPAGE
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#define HPAGE_PMD_SHIFT HPAGE_SHIFT
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#define HPAGE_PMD_MASK HPAGE_MASK
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#define HPAGE_PMD_SIZE HPAGE_SIZE
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#define transparent_hugepage_enabled(__vma) \
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((transparent_hugepage_flags & \
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(1<<TRANSPARENT_HUGEPAGE_FLAG) || \
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(transparent_hugepage_flags & \
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(1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG) && \
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((__vma)->vm_flags & VM_HUGEPAGE))) && \
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!((__vma)->vm_flags & VM_NOHUGEPAGE) && \
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!is_vma_temporary_stack(__vma))
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#define transparent_hugepage_defrag(__vma) \
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((transparent_hugepage_flags & \
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(1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)) || \
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(transparent_hugepage_flags & \
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(1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG) && \
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(__vma)->vm_flags & VM_HUGEPAGE))
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#ifdef CONFIG_DEBUG_VM
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#define transparent_hugepage_debug_cow() \
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(transparent_hugepage_flags & \
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(1<<TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG))
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#else /* CONFIG_DEBUG_VM */
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#define transparent_hugepage_debug_cow() 0
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#endif /* CONFIG_DEBUG_VM */
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extern unsigned long transparent_hugepage_flags;
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extern int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
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pmd_t *dst_pmd, pmd_t *src_pmd,
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struct vm_area_struct *vma,
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unsigned long addr, unsigned long end);
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extern int handle_pte_fault(struct mm_struct *mm,
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struct vm_area_struct *vma, unsigned long address,
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pte_t *pte, pmd_t *pmd, unsigned int flags);
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extern int split_huge_page(struct page *page);
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extern void __split_huge_page_pmd(struct mm_struct *mm, pmd_t *pmd);
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#define split_huge_page_pmd(__mm, __pmd) \
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do { \
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pmd_t *____pmd = (__pmd); \
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if (unlikely(pmd_trans_huge(*____pmd))) \
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__split_huge_page_pmd(__mm, ____pmd); \
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} while (0)
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#define wait_split_huge_page(__anon_vma, __pmd) \
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do { \
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pmd_t *____pmd = (__pmd); \
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spin_unlock_wait(&(__anon_vma)->root->lock); \
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/* \
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* spin_unlock_wait() is just a loop in C and so the \
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* CPU can reorder anything around it. \
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*/ \
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smp_mb(); \
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BUG_ON(pmd_trans_splitting(*____pmd) || \
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pmd_trans_huge(*____pmd)); \
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} while (0)
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#define HPAGE_PMD_ORDER (HPAGE_PMD_SHIFT-PAGE_SHIFT)
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#define HPAGE_PMD_NR (1<<HPAGE_PMD_ORDER)
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#if HPAGE_PMD_ORDER > MAX_ORDER
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#error "hugepages can't be allocated by the buddy allocator"
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#endif
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extern int hugepage_madvise(struct vm_area_struct *vma,
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unsigned long *vm_flags, int advice);
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extern void __vma_adjust_trans_huge(struct vm_area_struct *vma,
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unsigned long start,
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unsigned long end,
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long adjust_next);
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static inline void vma_adjust_trans_huge(struct vm_area_struct *vma,
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unsigned long start,
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unsigned long end,
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long adjust_next)
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{
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if (!vma->anon_vma || vma->vm_ops)
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return;
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__vma_adjust_trans_huge(vma, start, end, adjust_next);
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}
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static inline int hpage_nr_pages(struct page *page)
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{
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if (unlikely(PageTransHuge(page)))
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return HPAGE_PMD_NR;
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return 1;
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}
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static inline struct page *compound_trans_head(struct page *page)
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{
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if (PageTail(page)) {
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struct page *head;
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head = page->first_page;
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smp_rmb();
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/*
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* head may be a dangling pointer.
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* __split_huge_page_refcount clears PageTail before
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* overwriting first_page, so if PageTail is still
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* there it means the head pointer isn't dangling.
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*/
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if (PageTail(page))
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return head;
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}
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return page;
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}
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#else /* CONFIG_TRANSPARENT_HUGEPAGE */
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#define HPAGE_PMD_SHIFT ({ BUG(); 0; })
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#define HPAGE_PMD_MASK ({ BUG(); 0; })
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#define HPAGE_PMD_SIZE ({ BUG(); 0; })
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#define hpage_nr_pages(x) 1
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#define transparent_hugepage_enabled(__vma) 0
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#define transparent_hugepage_flags 0UL
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static inline int split_huge_page(struct page *page)
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{
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return 0;
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}
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#define split_huge_page_pmd(__mm, __pmd) \
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do { } while (0)
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#define wait_split_huge_page(__anon_vma, __pmd) \
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do { } while (0)
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#define compound_trans_head(page) compound_head(page)
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static inline int hugepage_madvise(struct vm_area_struct *vma,
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unsigned long *vm_flags, int advice)
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{
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BUG();
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return 0;
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}
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static inline void vma_adjust_trans_huge(struct vm_area_struct *vma,
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unsigned long start,
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unsigned long end,
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long adjust_next)
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{
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}
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#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
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#endif /* _LINUX_HUGE_MM_H */
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