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    Subject[PATCH 3.12 054/119] net: ratelimit warnings about dst entry refcount underflow or overflow
    Date
    From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>

    3.12-stable review patch. If anyone has any objections, please let me know.

    ===============

    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    machines with outdated 3.10.y kernels.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: Jiri Slaby <jslaby@suse.cz>
    ---
    net/core/dst.c | 4 +++-
    1 file changed, 3 insertions(+), 1 deletion(-)

    diff --git a/net/core/dst.c b/net/core/dst.c
    index c07070544e3f..31344009de25 100644
    --- a/net/core/dst.c
    +++ b/net/core/dst.c
    @@ -282,7 +282,9 @@ 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 (!newrefcnt && unlikely(dst->flags & DST_NOCACHE))
    call_rcu(&dst->rcu_head, dst_destroy_rcu);
    }
    --
    2.10.0
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