diff options
| author | Sahitya Tummala <stummala@codeaurora.org> | 2017-07-10 15:49:57 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-07-10 16:32:33 -0700 |
| commit | 2c80cd57c74339889a8752b20862a16c28929c3a (patch) | |
| tree | 91fe60fcb168a485c9616b2adb36a11eb719f5fa | |
| parent | 32e4e6d5cbb0c0e427391635991fe65e17797af8 (diff) | |
mm/list_lru.c: fix list_lru_count_node() to be race free
list_lru_count_node() iterates over all memcgs to get the total number of
entries on the node but it can race with memcg_drain_all_list_lrus(),
which migrates the entries from a dead cgroup to another. This can return
incorrect number of entries from list_lru_count_node().
Fix this by keeping track of entries per node and simply return it in
list_lru_count_node().
Link: http://lkml.kernel.org/r/1498707555-30525-1-git-send-email-stummala@codeaurora.org
Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Alexander Polakov <apolyakov@beget.ru>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | include/linux/list_lru.h | 1 | ||||
| -rw-r--r-- | mm/list_lru.c | 14 |
2 files changed, 7 insertions, 8 deletions
diff --git a/include/linux/list_lru.h b/include/linux/list_lru.h index cb0ba9f2a9a2..fa7fd03cb5f9 100644 --- a/include/linux/list_lru.h +++ b/include/linux/list_lru.h @@ -44,6 +44,7 @@ struct list_lru_node { /* for cgroup aware lrus points to per cgroup lists, otherwise NULL */ struct list_lru_memcg *memcg_lrus; #endif + long nr_items; } ____cacheline_aligned_in_smp; struct list_lru { diff --git a/mm/list_lru.c b/mm/list_lru.c index 234676e31edd..7a40fa2be858 100644 --- a/mm/list_lru.c +++ b/mm/list_lru.c @@ -117,6 +117,7 @@ bool list_lru_add(struct list_lru *lru, struct list_head *item) l = list_lru_from_kmem(nlru, item); list_add_tail(item, &l->list); l->nr_items++; + nlru->nr_items++; spin_unlock(&nlru->lock); return true; } @@ -136,6 +137,7 @@ bool list_lru_del(struct list_lru *lru, struct list_head *item) l = list_lru_from_kmem(nlru, item); list_del_init(item); l->nr_items--; + nlru->nr_items--; spin_unlock(&nlru->lock); return true; } @@ -183,15 +185,10 @@ EXPORT_SYMBOL_GPL(list_lru_count_one); unsigned long list_lru_count_node(struct list_lru *lru, int nid) { - long count = 0; - int memcg_idx; + struct list_lru_node *nlru; - count += __list_lru_count_one(lru, nid, -1); - if (list_lru_memcg_aware(lru)) { - for_each_memcg_cache_index(memcg_idx) - count += __list_lru_count_one(lru, nid, memcg_idx); - } - return count; + nlru = &lru->node[nid]; + return nlru->nr_items; } EXPORT_SYMBOL_GPL(list_lru_count_node); @@ -226,6 +223,7 @@ restart: assert_spin_locked(&nlru->lock); case LRU_REMOVED: isolated++; + nlru->nr_items--; /* * If the lru lock has been dropped, our list * traversal is now invalid and so we have to |