4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Vasily Averin vvs@virtuozzo.com
commit 4ecd55ea074217473f94cfee21bb72864d39f8d7 upstream.
After commit d202cce8963d, an expired cache_head can be removed from the cache_detail's hash.
However, the expired cache_head may be waiting for a reply from a previously submitted request. Such a cache_head has an increased refcounter and therefore it won't be freed after cache_put(freeme).
Because the cache_head was removed from the hash it cannot be found during cache_clean() and can be leaked forever, together with stalled cache_request and other taken resources.
In our case we noticed it because an entry in the export cache was holding a reference on a filesystem.
Fixes d202cce8963d ("sunrpc: never return expired entries in sunrpc_cache_lookup") Cc: Pavel Tikhomirov ptikhomirov@virtuozzo.com Cc: stable@kernel.org # 2.6.35 Signed-off-by: Vasily Averin vvs@virtuozzo.com Reviewed-by: NeilBrown neilb@suse.com Signed-off-by: J. Bruce Fields bfields@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/sunrpc/cache.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
--- a/net/sunrpc/cache.c +++ b/net/sunrpc/cache.c @@ -54,6 +54,11 @@ static void cache_init(struct cache_head h->last_refresh = now; }
+static void cache_fresh_locked(struct cache_head *head, time_t expiry, + struct cache_detail *detail); +static void cache_fresh_unlocked(struct cache_head *head, + struct cache_detail *detail); + struct cache_head *sunrpc_cache_lookup(struct cache_detail *detail, struct cache_head *key, int hash) { @@ -95,6 +100,7 @@ struct cache_head *sunrpc_cache_lookup(s if (cache_is_expired(detail, tmp)) { hlist_del_init(&tmp->cache_list); detail->entries --; + cache_fresh_locked(tmp, 0, detail); freeme = tmp; break; } @@ -110,8 +116,10 @@ struct cache_head *sunrpc_cache_lookup(s cache_get(new); write_unlock(&detail->hash_lock);
- if (freeme) + if (freeme) { + cache_fresh_unlocked(freeme, detail); cache_put(freeme, detail); + } return new; } EXPORT_SYMBOL_GPL(sunrpc_cache_lookup);