4.20-stable review patch. If anyone has any objections, please let me know.
------------------ From: Vasily Averin <[email protected]> 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 <[email protected]> Cc: [email protected] # 2.6.35 Signed-off-by: Vasily Averin <[email protected]> Reviewed-by: NeilBrown <[email protected]> Signed-off-by: J. Bruce Fields <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- 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); + static struct cache_head *sunrpc_cache_find_rcu(struct cache_detail *detail, struct cache_head *key, int hash) @@ -100,6 +105,7 @@ static struct cache_head *sunrpc_cache_a if (cache_is_expired(detail, tmp)) { hlist_del_init_rcu(&tmp->cache_list); detail->entries --; + cache_fresh_locked(tmp, 0, detail); freeme = tmp; break; } @@ -115,8 +121,10 @@ static struct cache_head *sunrpc_cache_a cache_get(new); spin_unlock(&detail->hash_lock); - if (freeme) + if (freeme) { + cache_fresh_unlocked(freeme, detail); cache_put(freeme, detail); + } return new; }
