318 lines
9.2 KiB
C
318 lines
9.2 KiB
C
#ifndef _LINUX_RMAP_H
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#define _LINUX_RMAP_H
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/*
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* Declarations for Reverse Mapping functions in mm/rmap.c
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*/
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#include <linux/list.h>
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#include <linux/slab.h>
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#include <linux/mm.h>
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#include <linux/rwsem.h>
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#include <linux/memcontrol.h>
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/*
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* The anon_vma heads a list of private "related" vmas, to scan if
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* an anonymous page pointing to this anon_vma needs to be unmapped:
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* the vmas on the list will be related by forking, or by splitting.
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*
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* Since vmas come and go as they are split and merged (particularly
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* in mprotect), the mapping field of an anonymous page cannot point
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* directly to a vma: instead it points to an anon_vma, on whose list
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* the related vmas can be easily linked or unlinked.
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*
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* After unlinking the last vma on the list, we must garbage collect
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* the anon_vma object itself: we're guaranteed no page can be
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* pointing to this anon_vma once its vma list is empty.
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*/
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struct anon_vma {
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struct anon_vma *root; /* Root of this anon_vma tree */
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struct rw_semaphore rwsem; /* W: modification, R: walking the list */
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/*
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* The refcount is taken on an anon_vma when there is no
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* guarantee that the vma of page tables will exist for
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* the duration of the operation. A caller that takes
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* the reference is responsible for clearing up the
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* anon_vma if they are the last user on release
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*/
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atomic_t refcount;
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/*
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* Count of child anon_vmas and VMAs which points to this anon_vma.
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*
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* This counter is used for making decision about reusing anon_vma
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* instead of forking new one. See comments in function anon_vma_clone.
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*/
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unsigned degree;
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struct anon_vma *parent; /* Parent of this anon_vma */
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/*
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* NOTE: the LSB of the rb_root.rb_node is set by
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* mm_take_all_locks() _after_ taking the above lock. So the
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* rb_root must only be read/written after taking the above lock
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* to be sure to see a valid next pointer. The LSB bit itself
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* is serialized by a system wide lock only visible to
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* mm_take_all_locks() (mm_all_locks_mutex).
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*/
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struct rb_root rb_root; /* Interval tree of private "related" vmas */
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};
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/*
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* The copy-on-write semantics of fork mean that an anon_vma
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* can become associated with multiple processes. Furthermore,
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* each child process will have its own anon_vma, where new
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* pages for that process are instantiated.
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*
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* This structure allows us to find the anon_vmas associated
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* with a VMA, or the VMAs associated with an anon_vma.
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* The "same_vma" list contains the anon_vma_chains linking
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* all the anon_vmas associated with this VMA.
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* The "rb" field indexes on an interval tree the anon_vma_chains
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* which link all the VMAs associated with this anon_vma.
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*/
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struct anon_vma_chain {
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struct vm_area_struct *vma;
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struct anon_vma *anon_vma;
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struct list_head same_vma; /* locked by mmap_sem & page_table_lock */
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struct rb_node rb; /* locked by anon_vma->rwsem */
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unsigned long rb_subtree_last;
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#ifdef CONFIG_DEBUG_VM_RB
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unsigned long cached_vma_start, cached_vma_last;
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#endif
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};
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enum ttu_flags {
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TTU_UNMAP = 1, /* unmap mode */
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TTU_MIGRATION = 2, /* migration mode */
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TTU_MUNLOCK = 4, /* munlock mode */
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TTU_LZFREE = 8, /* lazy free mode */
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TTU_SPLIT_HUGE_PMD = 16, /* split huge PMD if any */
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TTU_IGNORE_MLOCK = (1 << 8), /* ignore mlock */
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TTU_IGNORE_ACCESS = (1 << 9), /* don't age */
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TTU_IGNORE_HWPOISON = (1 << 10),/* corrupted page is recoverable */
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TTU_BATCH_FLUSH = (1 << 11), /* Batch TLB flushes where possible
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* and caller guarantees they will
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* do a final flush if necessary */
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TTU_RMAP_LOCKED = (1 << 12) /* do not grab rmap lock:
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* caller holds it */
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};
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#ifdef CONFIG_MMU
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static inline void get_anon_vma(struct anon_vma *anon_vma)
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{
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atomic_inc(&anon_vma->refcount);
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}
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void __put_anon_vma(struct anon_vma *anon_vma);
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static inline void put_anon_vma(struct anon_vma *anon_vma)
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{
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if (atomic_dec_and_test(&anon_vma->refcount))
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__put_anon_vma(anon_vma);
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}
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static inline void anon_vma_lock_write(struct anon_vma *anon_vma)
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{
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down_write(&anon_vma->root->rwsem);
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}
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static inline void anon_vma_unlock_write(struct anon_vma *anon_vma)
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{
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up_write(&anon_vma->root->rwsem);
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}
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static inline void anon_vma_lock_read(struct anon_vma *anon_vma)
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{
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down_read(&anon_vma->root->rwsem);
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}
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static inline void anon_vma_unlock_read(struct anon_vma *anon_vma)
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{
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up_read(&anon_vma->root->rwsem);
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}
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/*
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* anon_vma helper functions.
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*/
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void anon_vma_init(void); /* create anon_vma_cachep */
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int __anon_vma_prepare(struct vm_area_struct *);
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void unlink_anon_vmas(struct vm_area_struct *);
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int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *);
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int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *);
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static inline int anon_vma_prepare(struct vm_area_struct *vma)
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{
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if (likely(vma->anon_vma))
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return 0;
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return __anon_vma_prepare(vma);
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}
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static inline void anon_vma_merge(struct vm_area_struct *vma,
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struct vm_area_struct *next)
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{
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VM_BUG_ON_VMA(vma->anon_vma != next->anon_vma, vma);
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unlink_anon_vmas(next);
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}
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struct anon_vma *page_get_anon_vma(struct page *page);
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/* bitflags for do_page_add_anon_rmap() */
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#define RMAP_EXCLUSIVE 0x01
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#define RMAP_COMPOUND 0x02
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/*
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* rmap interfaces called when adding or removing pte of page
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*/
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void page_move_anon_rmap(struct page *, struct vm_area_struct *);
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void page_add_anon_rmap(struct page *, struct vm_area_struct *,
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unsigned long, bool);
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void do_page_add_anon_rmap(struct page *, struct vm_area_struct *,
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unsigned long, int);
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void page_add_new_anon_rmap(struct page *, struct vm_area_struct *,
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unsigned long, bool);
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void page_add_file_rmap(struct page *, bool);
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void page_remove_rmap(struct page *, bool);
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void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *,
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unsigned long);
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void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *,
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unsigned long);
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static inline void page_dup_rmap(struct page *page, bool compound)
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{
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atomic_inc(compound ? compound_mapcount_ptr(page) : &page->_mapcount);
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}
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/*
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* Called from mm/vmscan.c to handle paging out
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*/
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int page_referenced(struct page *, int is_locked,
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struct mem_cgroup *memcg, unsigned long *vm_flags);
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#define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)
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int try_to_unmap(struct page *, enum ttu_flags flags);
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/*
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* Used by uprobes to replace a userspace page safely
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*/
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pte_t *__page_check_address(struct page *, struct mm_struct *,
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unsigned long, spinlock_t **, int);
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static inline pte_t *page_check_address(struct page *page, struct mm_struct *mm,
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unsigned long address,
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spinlock_t **ptlp, int sync)
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{
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pte_t *ptep;
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__cond_lock(*ptlp, ptep = __page_check_address(page, mm, address,
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ptlp, sync));
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return ptep;
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}
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/*
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* Used by idle page tracking to check if a page was referenced via page
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* tables.
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*/
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#ifdef CONFIG_TRANSPARENT_HUGEPAGE
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bool page_check_address_transhuge(struct page *page, struct mm_struct *mm,
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unsigned long address, pmd_t **pmdp,
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pte_t **ptep, spinlock_t **ptlp);
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#else
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static inline bool page_check_address_transhuge(struct page *page,
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struct mm_struct *mm, unsigned long address,
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pmd_t **pmdp, pte_t **ptep, spinlock_t **ptlp)
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{
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*ptep = page_check_address(page, mm, address, ptlp, 0);
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*pmdp = NULL;
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return !!*ptep;
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}
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#endif
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/*
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* Used by swapoff to help locate where page is expected in vma.
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*/
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unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
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/*
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* Cleans the PTEs of shared mappings.
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* (and since clean PTEs should also be readonly, write protects them too)
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*
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* returns the number of cleaned PTEs.
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*/
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int page_mkclean(struct page *);
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/*
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* called in munlock()/munmap() path to check for other vmas holding
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* the page mlocked.
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*/
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int try_to_munlock(struct page *);
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void remove_migration_ptes(struct page *old, struct page *new, bool locked);
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/*
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* Called by memory-failure.c to kill processes.
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*/
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struct anon_vma *page_lock_anon_vma_read(struct page *page);
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void page_unlock_anon_vma_read(struct anon_vma *anon_vma);
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int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
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/*
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* rmap_walk_control: To control rmap traversing for specific needs
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*
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* arg: passed to rmap_one() and invalid_vma()
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* rmap_one: executed on each vma where page is mapped
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* done: for checking traversing termination condition
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* anon_lock: for getting anon_lock by optimized way rather than default
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* invalid_vma: for skipping uninterested vma
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*/
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struct rmap_walk_control {
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void *arg;
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int (*rmap_one)(struct page *page, struct vm_area_struct *vma,
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unsigned long addr, void *arg);
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int (*done)(struct page *page);
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struct anon_vma *(*anon_lock)(struct page *page);
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bool (*invalid_vma)(struct vm_area_struct *vma, void *arg);
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};
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int rmap_walk(struct page *page, struct rmap_walk_control *rwc);
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int rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc);
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#else /* !CONFIG_MMU */
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#define anon_vma_init() do {} while (0)
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#define anon_vma_prepare(vma) (0)
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#define anon_vma_link(vma) do {} while (0)
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static inline int page_referenced(struct page *page, int is_locked,
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struct mem_cgroup *memcg,
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unsigned long *vm_flags)
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{
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*vm_flags = 0;
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return 0;
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}
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#define try_to_unmap(page, refs) SWAP_FAIL
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static inline int page_mkclean(struct page *page)
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{
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return 0;
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}
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#endif /* CONFIG_MMU */
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/*
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* Return values of try_to_unmap
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*/
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#define SWAP_SUCCESS 0
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#define SWAP_AGAIN 1
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#define SWAP_FAIL 2
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#define SWAP_MLOCK 3
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#define SWAP_LZFREE 4
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#endif /* _LINUX_RMAP_H */
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