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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_RMAP_H
#define _LINUX_RMAP_H
* Declarations for Reverse Mapping functions in mm/rmap.c
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/rwsem.h>
#include <linux/memcontrol.h>
#include <linux/highmem.h>
* The anon_vma heads a list of private "related" vmas, to scan if
* an anonymous page pointing to this anon_vma needs to be unmapped:
* the vmas on the list will be related by forking, or by splitting.
* Since vmas come and go as they are split and merged (particularly
* in mprotect), the mapping field of an anonymous page cannot point
* directly to a vma: instead it points to an anon_vma, on whose list
* the related vmas can be easily linked or unlinked.
* After unlinking the last vma on the list, we must garbage collect
* the anon_vma object itself: we're guaranteed no page can be
* pointing to this anon_vma once its vma list is empty.
struct anon_vma {
struct anon_vma *root; /* Root of this anon_vma tree */
struct rw_semaphore rwsem; /* W: modification, R: walking the list */
* The refcount is taken on an anon_vma when there is no
* guarantee that the vma of page tables will exist for
* the duration of the operation. A caller that takes
* the reference is responsible for clearing up the
* anon_vma if they are the last user on release
atomic_t refcount;
* Count of child anon_vmas and VMAs which points to this anon_vma.
* This counter is used for making decision about reusing anon_vma
* instead of forking new one. See comments in function anon_vma_clone.
unsigned degree;
struct anon_vma *parent; /* Parent of this anon_vma */
* NOTE: the LSB of the rb_root.rb_node is set by
* mm_take_all_locks() _after_ taking the above lock. So the
* rb_root must only be read/written after taking the above lock
* to be sure to see a valid next pointer. The LSB bit itself
* is serialized by a system wide lock only visible to
* mm_take_all_locks() (mm_all_locks_mutex).
/* Interval tree of private "related" vmas */
struct rb_root_cached rb_root;
* The copy-on-write semantics of fork mean that an anon_vma
* can become associated with multiple processes. Furthermore,
* each child process will have its own anon_vma, where new
* pages for that process are instantiated.
* This structure allows us to find the anon_vmas associated
* with a VMA, or the VMAs associated with an anon_vma.
* The "same_vma" list contains the anon_vma_chains linking
* all the anon_vmas associated with this VMA.
* The "rb" field indexes on an interval tree the anon_vma_chains
* which link all the VMAs associated with this anon_vma.
struct anon_vma_chain {
struct vm_area_struct *vma;
struct anon_vma *anon_vma;
struct list_head same_vma; /* locked by mmap_sem & page_table_lock */
struct rb_node rb; /* locked by anon_vma->rwsem */
unsigned long rb_subtree_last;
unsigned long cached_vma_start, cached_vma_last;
enum ttu_flags {
TTU_MIGRATION = 0x1, /* migration mode */
TTU_MUNLOCK = 0x2, /* munlock mode */
TTU_SPLIT_HUGE_PMD = 0x4, /* split huge PMD if any */
TTU_IGNORE_MLOCK = 0x8, /* ignore mlock */
TTU_IGNORE_ACCESS = 0x10, /* don't age */
TTU_IGNORE_HWPOISON = 0x20, /* corrupted page is recoverable */
TTU_BATCH_FLUSH = 0x40, /* Batch TLB flushes where possible
* and caller guarantees they will
* do a final flush if necessary */
TTU_RMAP_LOCKED = 0x80, /* do not grab rmap lock:
* caller holds it */
TTU_SPLIT_FREEZE = 0x100, /* freeze pte under splitting thp */
static inline void get_anon_vma(struct anon_vma *anon_vma)
void __put_anon_vma(struct anon_vma *anon_vma);
static inline void put_anon_vma(struct anon_vma *anon_vma)
if (atomic_dec_and_test(&anon_vma->refcount))
static inline void anon_vma_lock_write(struct anon_vma *anon_vma)
static inline void anon_vma_unlock_write(struct anon_vma *anon_vma)
static inline void anon_vma_lock_read(struct anon_vma *anon_vma)
static inline void anon_vma_unlock_read(struct anon_vma *anon_vma)
* anon_vma helper functions.
void anon_vma_init(void); /* create anon_vma_cachep */
int __anon_vma_prepare(struct vm_area_struct *);
void unlink_anon_vmas(struct vm_area_struct *);
int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *);
int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *);
static inline int anon_vma_prepare(struct vm_area_struct *vma)
if (likely(vma->anon_vma))
return 0;
return __anon_vma_prepare(vma);
static inline void anon_vma_merge(struct vm_area_struct *vma,
struct vm_area_struct *next)
VM_BUG_ON_VMA(vma->anon_vma != next->anon_vma, vma);
struct anon_vma *page_get_anon_vma(struct page *page);
/* bitflags for do_page_add_anon_rmap() */
#define RMAP_EXCLUSIVE 0x01
#define RMAP_COMPOUND 0x02
* rmap interfaces called when adding or removing pte of page
void page_move_anon_rmap(struct page *, struct vm_area_struct *);
void page_add_anon_rmap(struct page *, struct vm_area_struct *,
unsigned long, bool);
void do_page_add_anon_rmap(struct page *, struct vm_area_struct *,
unsigned long, int);
void page_add_new_anon_rmap(struct page *, struct vm_area_struct *,
unsigned long, bool);
void page_add_file_rmap(struct page *, bool);
void page_remove_rmap(struct page *, bool);
void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *,
unsigned long);
void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *,
unsigned long);
static inline void page_dup_rmap(struct page *page, bool compound)
atomic_inc(compound ? compound_mapcount_ptr(page) : &page->_mapcount);
* Called from mm/vmscan.c to handle paging out
int page_referenced(struct page *, int is_locked,
struct mem_cgroup *memcg, unsigned long *vm_flags);
bool try_to_unmap(struct page *, enum ttu_flags flags);
/* Avoid racy checks */
#define PVMW_SYNC (1 << 0)
/* Look for migarion entries rather than present PTEs */
#define PVMW_MIGRATION (1 << 1)
struct page_vma_mapped_walk {
struct page *page;
struct vm_area_struct *vma;
unsigned long address;
pmd_t *pmd;
pte_t *pte;
spinlock_t *ptl;
unsigned int flags;
static inline void page_vma_mapped_walk_done(struct page_vma_mapped_walk *pvmw)
if (pvmw->pte)
if (pvmw->ptl)
bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw);
* Used by swapoff to help locate where page is expected in vma.
unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
* Cleans the PTEs of shared mappings.
* (and since clean PTEs should also be readonly, write protects them too)
* returns the number of cleaned PTEs.
int page_mkclean(struct page *);
* called in munlock()/munmap() path to check for other vmas holding
* the page mlocked.
void try_to_munlock(struct page *);
void remove_migration_ptes(struct page *old, struct page *new, bool locked);
* Called by memory-failure.c to kill processes.
struct anon_vma *page_lock_anon_vma_read(struct page *page);
void page_unlock_anon_vma_read(struct anon_vma *anon_vma);
int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
* rmap_walk_control: To control rmap traversing for specific needs
* arg: passed to rmap_one() and invalid_vma()
* rmap_one: executed on each vma where page is mapped
* done: for checking traversing termination condition
* anon_lock: for getting anon_lock by optimized way rather than default
* invalid_vma: for skipping uninterested vma
struct rmap_walk_control {
void *arg;
* Return false if page table scanning in rmap_walk should be stopped.
* Otherwise, return true.
bool (*rmap_one)(struct page *page, struct vm_area_struct *vma,
unsigned long addr, void *arg);
int (*done)(struct page *page);
struct anon_vma *(*anon_lock)(struct page *page);
bool (*invalid_vma)(struct vm_area_struct *vma, void *arg);
void rmap_walk(struct page *page, struct rmap_walk_control *rwc);
void rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc);
#else /* !CONFIG_MMU */
#define anon_vma_init() do {} while (0)
#define anon_vma_prepare(vma) (0)
#define anon_vma_link(vma) do {} while (0)
static inline int page_referenced(struct page *page, int is_locked,
struct mem_cgroup *memcg,
unsigned long *vm_flags)
*vm_flags = 0;
return 0;
#define try_to_unmap(page, refs) false
static inline int page_mkclean(struct page *page)
return 0;
#endif /* CONFIG_MMU */
#endif /* _LINUX_RMAP_H */