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8e321fefb0
The arbitrary restriction on page counts offered by the core migrate_page_move_mapping() code results in rather suspicious looking fiddling with page reference counts in the aio_migratepage() operation. To fix this, make migrate_page_move_mapping() take an extra_count parameter that allows aio to tell the code about its own reference count on the page being migrated. While cleaning up aio_migratepage(), make it validate that the old page being passed in is actually what aio_migratepage() expects to prevent misbehaviour in the case of races. Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
136 lines
4.3 KiB
C
136 lines
4.3 KiB
C
#ifndef _LINUX_MIGRATE_H
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#define _LINUX_MIGRATE_H
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#include <linux/mm.h>
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#include <linux/mempolicy.h>
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#include <linux/migrate_mode.h>
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typedef struct page *new_page_t(struct page *, unsigned long private, int **);
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/*
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* Return values from addresss_space_operations.migratepage():
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* - negative errno on page migration failure;
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* - zero on page migration success;
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*
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* The balloon page migration introduces this special case where a 'distinct'
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* return code is used to flag a successful page migration to unmap_and_move().
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* This approach is necessary because page migration can race against balloon
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* deflation procedure, and for such case we could introduce a nasty page leak
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* if a successfully migrated balloon page gets released concurrently with
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* migration's unmap_and_move() wrap-up steps.
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*/
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#define MIGRATEPAGE_SUCCESS 0
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#define MIGRATEPAGE_BALLOON_SUCCESS 1 /* special ret code for balloon page
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* sucessful migration case.
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*/
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enum migrate_reason {
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MR_COMPACTION,
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MR_MEMORY_FAILURE,
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MR_MEMORY_HOTPLUG,
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MR_SYSCALL, /* also applies to cpusets */
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MR_MEMPOLICY_MBIND,
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MR_NUMA_MISPLACED,
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MR_CMA
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};
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#ifdef CONFIG_MIGRATION
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extern void putback_lru_pages(struct list_head *l);
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extern void putback_movable_pages(struct list_head *l);
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extern int migrate_page(struct address_space *,
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struct page *, struct page *, enum migrate_mode);
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extern int migrate_pages(struct list_head *l, new_page_t x,
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unsigned long private, enum migrate_mode mode, int reason);
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extern int fail_migrate_page(struct address_space *,
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struct page *, struct page *);
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extern int migrate_prep(void);
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extern int migrate_prep_local(void);
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extern int migrate_vmas(struct mm_struct *mm,
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const nodemask_t *from, const nodemask_t *to,
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unsigned long flags);
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extern void migrate_page_copy(struct page *newpage, struct page *page);
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extern int migrate_huge_page_move_mapping(struct address_space *mapping,
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struct page *newpage, struct page *page);
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extern int migrate_page_move_mapping(struct address_space *mapping,
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struct page *newpage, struct page *page,
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struct buffer_head *head, enum migrate_mode mode,
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int extra_count);
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#else
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static inline void putback_lru_pages(struct list_head *l) {}
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static inline void putback_movable_pages(struct list_head *l) {}
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static inline int migrate_pages(struct list_head *l, new_page_t x,
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unsigned long private, enum migrate_mode mode, int reason)
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{ return -ENOSYS; }
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static inline int migrate_prep(void) { return -ENOSYS; }
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static inline int migrate_prep_local(void) { return -ENOSYS; }
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static inline int migrate_vmas(struct mm_struct *mm,
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const nodemask_t *from, const nodemask_t *to,
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unsigned long flags)
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{
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return -ENOSYS;
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}
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static inline void migrate_page_copy(struct page *newpage,
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struct page *page) {}
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static inline int migrate_huge_page_move_mapping(struct address_space *mapping,
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struct page *newpage, struct page *page)
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{
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return -ENOSYS;
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}
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/* Possible settings for the migrate_page() method in address_operations */
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#define migrate_page NULL
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#define fail_migrate_page NULL
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#endif /* CONFIG_MIGRATION */
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#ifdef CONFIG_NUMA_BALANCING
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extern bool pmd_trans_migrating(pmd_t pmd);
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extern void wait_migrate_huge_page(struct anon_vma *anon_vma, pmd_t *pmd);
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extern int migrate_misplaced_page(struct page *page,
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struct vm_area_struct *vma, int node);
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extern bool migrate_ratelimited(int node);
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#else
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static inline bool pmd_trans_migrating(pmd_t pmd)
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{
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return false;
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}
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static inline void wait_migrate_huge_page(struct anon_vma *anon_vma, pmd_t *pmd)
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{
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}
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static inline int migrate_misplaced_page(struct page *page,
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struct vm_area_struct *vma, int node)
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{
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return -EAGAIN; /* can't migrate now */
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}
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static inline bool migrate_ratelimited(int node)
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{
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return false;
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}
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#endif /* CONFIG_NUMA_BALANCING */
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#if defined(CONFIG_NUMA_BALANCING) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
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extern int migrate_misplaced_transhuge_page(struct mm_struct *mm,
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struct vm_area_struct *vma,
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pmd_t *pmd, pmd_t entry,
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unsigned long address,
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struct page *page, int node);
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#else
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static inline int migrate_misplaced_transhuge_page(struct mm_struct *mm,
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struct vm_area_struct *vma,
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pmd_t *pmd, pmd_t entry,
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unsigned long address,
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struct page *page, int node)
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{
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return -EAGAIN;
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}
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#endif /* CONFIG_NUMA_BALANCING && CONFIG_TRANSPARENT_HUGEPAGE*/
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#endif /* _LINUX_MIGRATE_H */
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