net: ratelimit warnings about dst entry refcount underflow or overflow

Kernel generates a lot of warnings when dst entry reference counter
overflows and becomes negative. That bug was seen several times at
machines with outdated 3.10.y kernels. Most like it's already fixed
in upstream. Anyway that flood completely kills machine and makes
further debugging impossible.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/dst.c b/net/core/dst.c
index e956ce6d13782f2da0a229cabafef663665159eb..002144bea93517d7e2e5b2c0ac00e70c028174a2 100644 (file)
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -284,7 +284,9 @@ void dst_release(struct dst_entry *dst)
                int newrefcnt;
 
                newrefcnt = atomic_dec_return(&dst->__refcnt);
-               WARN_ON(newrefcnt < 0);
+               if (unlikely(newrefcnt < 0))
+                       net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
+                                            __func__, dst, newrefcnt);
                if (unlikely(dst->flags & DST_NOCACHE) && !newrefcnt)
                        call_rcu(&dst->rcu_head, dst_destroy_rcu);
        }