From: Florian Westphal <fw@strlen.de>
To: Florian Westphal <fw@strlen.de>
Cc: netfilter-devel@vger.kernel.org
Subject: Re: [PATCH nf] netfilter: conntrack: resched in nf_ct_iterate_cleanup
Date: Fri, 11 Dec 2015 15:43:13 +0100 [thread overview]
Message-ID: <20151211144313.GD8811@breakpoint.cc> (raw)
In-Reply-To: <1449682209-20330-1-git-send-email-fw@strlen.de>
Florian Westphal <fw@strlen.de> wrote:
> Ulrich reports soft lockup with following (shortened) callchain:
>
> NMI watchdog: BUG: soft lockup - CPU#1 stuck for 22s!
> __netif_receive_skb_core+0x6e4/0x774
> process_backlog+0x94/0x160
> net_rx_action+0x88/0x178
> call_do_softirq+0x24/0x3c
> do_softirq+0x54/0x6c
> __local_bh_enable_ip+0x7c/0xbc
> nf_ct_iterate_cleanup+0x11c/0x22c [nf_conntrack]
> masq_inet_event+0x20/0x30 [nf_nat_masquerade_ipv6]
> atomic_notifier_call_chain+0x1c/0x2c
> ipv6_del_addr+0x1bc/0x220 [ipv6]
>
> Problem is that nf_ct_iterate_cleanup can run for a very long time
> since it can be interrupted by softirq processing.
> Moreover, atomic_notifier_call_chain runs with rcu readlock held.
Ulrich just reported another softlockup even with this patch applied.
One explanation would be non-matching iter(), in this case
get_next_corpse can take forever since it will walk the entire conntrack
table, rendering the cond_resched moot.
A V2 patch will be coming to also add a lock break + resched to
get_next_corpse.
I'll mark it as 'changes requested' in patchwork.
next prev parent reply other threads:[~2015-12-11 14:43 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-09 17:30 [PATCH nf] netfilter: conntrack: resched in nf_ct_iterate_cleanup Florian Westphal
2015-12-11 11:42 ` Pablo Neira Ayuso
2015-12-11 11:53 ` Florian Westphal
2015-12-11 14:43 ` Florian Westphal [this message]
2015-12-11 17:16 ` Pablo Neira Ayuso
2015-12-11 17:21 ` Florian Westphal
-- strict thread matches above, loose matches on Subject: below --
2016-01-20 10:16 Florian Westphal
2016-02-01 17:38 ` Pablo Neira Ayuso
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