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Message-ID: <1414370826.16231.1.camel@edumazet-glaptop2.roam.corp.google.com> Date: Sun, 26 Oct 2014 17:47:06 -0700 From: Eric Dumazet <eric.dumazet@...il.com> To: Nikolay Aleksandrov <nikolay@...hat.com> Cc: Florian Westphal <fw@...len.de>, Stephen Hemminger <stephen@...workplumber.org>, netdev@...r.kernel.org Subject: Re: Fw: [Bug 86851] New: Reproducible panic on heavy UDP traffic On Mon, 2014-10-27 at 00:28 +0100, Nikolay Aleksandrov wrote: > > Thanks for CCing me. > I'll dig in the code tomorrow but my first thought when I saw this was > could it be possible that we have a race condition between > ip_frag_queue() and inet_frag_evict(), more precisely between the > ipq_kill() calls from ip_frag_queue and inet_frag_evict since the frag > could be found before we have entered the evictor which then can add it to > its expire list but the ipq_kill() from ip_frag_queue() can do a list_del > after we release the chain lock in the evictor so we may end up like this ? Yes, either we use hlist_del_init() but loose poison aid, or test if frag was evicted : Not sure about refcount. diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c index 9eb89f3f0ee4..894ec30c5896 100644 --- a/net/ipv4/inet_fragment.c +++ b/net/ipv4/inet_fragment.c @@ -285,7 +285,8 @@ static inline void fq_unlink(struct inet_frag_queue *fq, struct inet_frags *f) struct inet_frag_bucket *hb; hb = get_frag_bucket_locked(fq, f); - hlist_del(&fq->list); + if (!(fq->flags & INET_FRAG_EVICTED)) + hlist_del(&fq->list); spin_unlock(&hb->chain_lock); } -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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