1 files changed, 35 insertions, 9 deletions

diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c
index 2bc7bb82b162..360decdddc78 100644
--- a/net/sunrpc/auth.c
+++ b/net/sunrpc/auth.c
@@ -80,6 +80,10 @@ static struct kernel_param_ops param_ops_hashtbl_sz = {
 module_param_named(auth_hashtable_size, auth_hashbits, hashtbl_sz, 0644);
 MODULE_PARM_DESC(auth_hashtable_size, "RPC credential cache hashtable size");
 
+static unsigned long auth_max_cred_cachesize = ULONG_MAX;
+module_param(auth_max_cred_cachesize, ulong, 0644);
+MODULE_PARM_DESC(auth_max_cred_cachesize, "RPC credential maximum total cache size");
+
 static u32
 pseudoflavor_to_flavor(u32 flavor) {
         if (flavor > RPC_AUTH_MAXFLAVOR)
@@ -481,6 +485,20 @@ rpcauth_prune_expired(struct list_head *free, int nr_to_scan)
         return freed;
 }
 
+static unsigned long
+rpcauth_cache_do_shrink(int nr_to_scan)
+{
+        LIST_HEAD(free);
+        unsigned long freed;
+
+        spin_lock(&rpc_credcache_lock);
+        freed = rpcauth_prune_expired(&free, nr_to_scan);
+        spin_unlock(&rpc_credcache_lock);
+        rpcauth_destroy_credlist(&free);
+
+        return freed;
+}
+
 /*
  * Run memory cache shrinker.
  */
@@ -488,9 +506,6 @@ static unsigned long
 rpcauth_cache_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
 
 {
-        LIST_HEAD(free);
-        unsigned long freed;
-
         if ((sc->gfp_mask & GFP_KERNEL) != GFP_KERNEL)
                 return SHRINK_STOP;
 
@@ -498,12 +513,7 @@ rpcauth_cache_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
         if (list_empty(&cred_unused))
                 return SHRINK_STOP;
 
-        spin_lock(&rpc_credcache_lock);
-        freed = rpcauth_prune_expired(&free, sc->nr_to_scan);
-        spin_unlock(&rpc_credcache_lock);
-        rpcauth_destroy_credlist(&free);
-
-        return freed;
+        return rpcauth_cache_do_shrink(sc->nr_to_scan);
 }
 
 static unsigned long
@@ -513,6 +523,21 @@ rpcauth_cache_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
         return (number_cred_unused / 100) * sysctl_vfs_cache_pressure;
 }
 
+static void
+rpcauth_cache_enforce_limit(void)
+{
+        unsigned long diff;
+        unsigned int nr_to_scan;
+
+        if (number_cred_unused <= auth_max_cred_cachesize)
+                return;
+        diff = number_cred_unused - auth_max_cred_cachesize;
+        nr_to_scan = 100;
+        if (diff < nr_to_scan)
+                nr_to_scan = diff;
+        rpcauth_cache_do_shrink(nr_to_scan);
+}
+
 /*
  * Look up a process' credentials in the authentication cache
  */
@@ -566,6 +591,7 @@ rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred,
         } else
                 list_add_tail(&new->cr_lru, &free);
         spin_unlock(&cache->lock);
+        rpcauth_cache_enforce_limit();
 found:
         if (test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags) &&
             cred->cr_ops->cr_init != NULL &&