diff options
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/zswap.c | 21 |
1 files changed, 12 insertions, 9 deletions
diff --git a/mm/zswap.c b/mm/zswap.c index 87b204233115..62195f72bf56 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -355,12 +355,14 @@ static int zswap_rb_insert(struct rb_root *root, struct zswap_entry *entry, return 0; } -static void zswap_rb_erase(struct rb_root *root, struct zswap_entry *entry) +static bool zswap_rb_erase(struct rb_root *root, struct zswap_entry *entry) { if (!RB_EMPTY_NODE(&entry->rbnode)) { rb_erase(&entry->rbnode, root); RB_CLEAR_NODE(&entry->rbnode); + return true; } + return false; } /* @@ -599,14 +601,16 @@ static struct zswap_pool *zswap_pool_find_get(char *type, char *compressor) return NULL; } +/* + * If the entry is still valid in the tree, drop the initial ref and remove it + * from the tree. This function must be called with an additional ref held, + * otherwise it may race with another invalidation freeing the entry. + */ static void zswap_invalidate_entry(struct zswap_tree *tree, struct zswap_entry *entry) { - /* remove from rbtree */ - zswap_rb_erase(&tree->rbroot, entry); - - /* drop the initial reference from entry creation */ - zswap_entry_put(tree, entry); + if (zswap_rb_erase(&tree->rbroot, entry)) + zswap_entry_put(tree, entry); } static int zswap_reclaim_entry(struct zswap_pool *pool) @@ -659,8 +663,7 @@ static int zswap_reclaim_entry(struct zswap_pool *pool) * swapcache. Drop the entry from zswap - unless invalidate already * took it out while we had the tree->lock released for IO. */ - if (entry == zswap_rb_search(&tree->rbroot, swpoffset)) - zswap_invalidate_entry(tree, entry); + zswap_invalidate_entry(tree, entry); put_unlock: /* Drop local reference */ @@ -1466,7 +1469,6 @@ stats: count_objcg_event(entry->objcg, ZSWPIN); freeentry: spin_lock(&tree->lock); - zswap_entry_put(tree, entry); if (!ret && zswap_exclusive_loads_enabled) { zswap_invalidate_entry(tree, entry); *exclusive = true; @@ -1475,6 +1477,7 @@ freeentry: list_move(&entry->lru, &entry->pool->lru); spin_unlock(&entry->pool->lru_lock); } + zswap_entry_put(tree, entry); spin_unlock(&tree->lock); return ret; |