net: ratelimit warnings about dst entry refcount underflow or overflow

commit 8bf4ada2e21378816b28205427ee6b0e1ca4c5f1 upstream.

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machines with outdated 3.10.y kernels.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>
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/net/core/dst.c b/net/core/dst.c
index 1bf6842b89b82f75d329679366baba8f173a6e9e..582b861aeba61598009d6bb37bd4661490b70cae 100644 (file)
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -283,7 +283,9 @@ void dst_release(struct dst_entry *dst)
                unsigned short nocache = dst->flags & DST_NOCACHE;
 
                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 (!newrefcnt && unlikely(nocache))
                        call_rcu(&dst->rcu_head, dst_destroy_rcu);
        }