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Anonymous Virtual Memory Area

include/mem/anon_vma.h View source View on GitHub

LOCK ORDERING:

mmap_lock
└─ anon_vma->root->lock
   └─ folio_lock

Structs

Section titled “Structs”

anon_vma

Section titled “anon_vma”
struct anon_vma (5 fields) source
§ struct rbit tree

AVCs, keyed in OBJECT-SPACE [pgoff, pgoff+npages)

§ struct anon_vma *root

oldest ancestor, the lock is here

§ struct anon_vma *parent

immediate ancestor in fork hierarchy

§ struct rwlock lock

acquire via root

§ refcount_t refcount

AVCs + folios referencing this object

Functions

Section titled “Functions”

anon_vma_alloc

Section titled “anon_vma_alloc”
struct anon_vma * anon_vma_alloc(void)
source

anon_vma_free

Section titled “anon_vma_free”
void anon_vma_free(struct anon_vma *av)
source

refcount==0 only

anon_vma_fork

Section titled “anon_vma_fork”
enum err anon_vma_fork(
    struct vma_range *child,
    struct vma_range *parent
)
source

anon_vma_read_lock

Section titled “anon_vma_read_lock”
void anon_vma_read_lock(struct anon_vma *av)
source

root->lock

anon_vma_unlock

Section titled “anon_vma_unlock”
void anon_vma_unlock(struct anon_vma *av)
source

anon_vma_write_lock

Section titled “anon_vma_write_lock”
void anon_vma_write_lock(struct anon_vma *av)
source

anon_vma_clone

Section titled “anon_vma_clone”
enum err anon_vma_clone(struct vma_range *dst, struct vma_range *src)
source

anon_vma_itree_first

Section titled “anon_vma_itree_first”
struct anon_vma_chain * anon_vma_itree_first(
    struct anon_vma *av,
    pgoff_t first,
    pgoff_t last
)
source

anon_vma_itree_next

Section titled “anon_vma_itree_next”
struct anon_vma_chain * anon_vma_itree_next(
    struct anon_vma_chain *avc,
    pgoff_t first,
    pgoff_t last
)
source
Section titled “vma_range_unlink_anon_vmas”
void vma_range_unlink_anon_vmas(struct vma_range *vma_range)
source

teardown: unlink all AVCs on this vma_range, drop anon_vma refs

anon_vma_is_root

Section titled “anon_vma_is_root”
bool anon_vma_is_root(const struct anon_vma *av)
source

anon_vma_getref

Section titled “anon_vma_getref”
bool anon_vma_getref(struct anon_vma *av)
source

anon_vma_putref

Section titled “anon_vma_putref”
void anon_vma_putref(struct anon_vma *av)
source

Drop ref: When forked anon_vma dies it releases its root pin, allowing the putref to go up the hierarchy, but it’s bounded, as root is its own root