diff options
Diffstat (limited to 'mm/rmap.c')
| -rw-r--r-- | mm/rmap.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 0feeef860a8..f522cb00864 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -250,7 +250,8 @@ static void anon_vma_unlink(struct anon_vma_chain *anon_vma_chain) list_del(&anon_vma_chain->same_anon_vma); /* We must garbage collect the anon_vma if it's empty */ - empty = list_empty(&anon_vma->head) && !ksm_refcount(anon_vma); + empty = list_empty(&anon_vma->head) && !ksm_refcount(anon_vma) && + !migrate_refcount(anon_vma); spin_unlock(&anon_vma->lock); if (empty) @@ -275,6 +276,7 @@ static void anon_vma_ctor(void *data) spin_lock_init(&anon_vma->lock); ksm_refcount_init(anon_vma); + migrate_refcount_init(anon_vma); INIT_LIST_HEAD(&anon_vma->head); } @@ -1355,10 +1357,8 @@ static int rmap_walk_anon(struct page *page, int (*rmap_one)(struct page *, /* * Note: remove_migration_ptes() cannot use page_lock_anon_vma() * because that depends on page_mapped(); but not all its usages - * are holding mmap_sem, which also gave the necessary guarantee - * (that this anon_vma's slab has not already been destroyed). - * This needs to be reviewed later: avoiding page_lock_anon_vma() - * is risky, and currently limits the usefulness of rmap_walk(). + * are holding mmap_sem. Users without mmap_sem are required to + * take a reference count to prevent the anon_vma disappearing */ anon_vma = page_anon_vma(page); if (!anon_vma) |