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authorSahitya Tummala <stummala@codeaurora.org>2017-07-10 15:49:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-07-10 16:32:33 -0700
commit2c80cd57c74339889a8752b20862a16c28929c3a (patch)
tree91fe60fcb168a485c9616b2adb36a11eb719f5fa
parent32e4e6d5cbb0c0e427391635991fe65e17797af8 (diff)
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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.h1
-rw-r--r--mm/list_lru.c14
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