668f9abbd4
Commit bf6bddf192 ("mm: introduce compaction and migration for
ballooned pages") introduces page_count(page) into memory compaction
which dereferences page->first_page if PageTail(page).
This results in a very rare NULL pointer dereference on the
aforementioned page_count(page). Indeed, anything that does
compound_head(), including page_count() is susceptible to racing with
prep_compound_page() and seeing a NULL or dangling page->first_page
pointer.
This patch uses Andrea's implementation of compound_trans_head() that
deals with such a race and makes it the default compound_head()
implementation. This includes a read memory barrier that ensures that
if PageTail(head) is true that we return a head page that is neither
NULL nor dangling. The patch then adds a store memory barrier to
prep_compound_page() to ensure page->first_page is set.
This is the safest way to ensure we see the head page that we are
expecting, PageTail(page) is already in the unlikely() path and the
memory barriers are unfortunately required.
Hugetlbfs is the exception, we don't enforce a store memory barrier
during init since no race is possible.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Holger Kiehl <Holger.Kiehl@dwd.de>
Cc: Christoph Lameter <cl@linux.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
215 lines
6.9 KiB
C
215 lines
6.9 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 void huge_pmd_set_accessed(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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pmd_t orig_pmd, int dirty);
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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 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
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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, unsigned long addr);
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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 move_huge_pmd(struct vm_area_struct *vma,
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struct vm_area_struct *new_vma,
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unsigned long old_addr,
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unsigned long new_addr, unsigned long old_end,
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pmd_t *old_pmd, pmd_t *new_pmd);
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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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int prot_numa);
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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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TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_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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spinlock_t **ptl);
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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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#ifdef CONFIG_TRANSPARENT_HUGEPAGE
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#define HPAGE_PMD_SHIFT PMD_SHIFT
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#define HPAGE_PMD_SIZE ((1UL) << HPAGE_PMD_SHIFT)
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#define HPAGE_PMD_MASK (~(HPAGE_PMD_SIZE - 1))
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extern bool is_vma_temporary_stack(struct vm_area_struct *vma);
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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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#define transparent_hugepage_use_zero_page() \
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(transparent_hugepage_flags & \
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(1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG))
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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 split_huge_page_to_list(struct page *page, struct list_head *list);
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static inline int split_huge_page(struct page *page)
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{
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return split_huge_page_to_list(page, NULL);
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}
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extern void __split_huge_page_pmd(struct vm_area_struct *vma,
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unsigned long address, pmd_t *pmd);
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#define split_huge_page_pmd(__vma, __address, __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(__vma, __address, \
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____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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anon_vma_lock_write(__anon_vma); \
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anon_vma_unlock_write(__anon_vma); \
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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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extern void split_huge_page_pmd_mm(struct mm_struct *mm, unsigned long address,
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pmd_t *pmd);
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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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extern int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
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spinlock_t **ptl);
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/* mmap_sem must be held on entry */
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static inline int pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
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spinlock_t **ptl)
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{
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VM_BUG_ON(!rwsem_is_locked(&vma->vm_mm->mmap_sem));
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if (pmd_trans_huge(*pmd))
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return __pmd_trans_huge_lock(pmd, vma, ptl);
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else
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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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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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extern int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
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unsigned long addr, pmd_t pmd, pmd_t *pmdp);
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#else /* CONFIG_TRANSPARENT_HUGEPAGE */
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#define HPAGE_PMD_SHIFT ({ BUILD_BUG(); 0; })
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#define HPAGE_PMD_MASK ({ BUILD_BUG(); 0; })
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#define HPAGE_PMD_SIZE ({ BUILD_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
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split_huge_page_to_list(struct page *page, struct list_head *list)
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{
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return 0;
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}
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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(__vma, __address, __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 split_huge_page_pmd_mm(__mm, __address, __pmd) \
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do { } while (0)
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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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static inline int pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
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spinlock_t **ptl)
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{
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return 0;
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}
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static inline int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
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unsigned long addr, pmd_t pmd, pmd_t *pmdp)
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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_HUGE_MM_H */
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