netdev - Re: Kernel 4.1 hang, apparently in __inet_lookup

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Message-ID: <56492A39.2060307@fastly.com>
Date:	Sun, 15 Nov 2015 16:58:33 -0800
From:	Grant Zhang <gzhang@...tly.com>
To:	Eric Dumazet <eric.dumazet@...il.com>,
	Patrick Schaaf <kernelorg@....de>
Cc:	NETDEV <netdev@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: Kernel 4.1 hang, apparently in __inet_lookup_established

Hi Patrick,

Have you tried the two patches Eric mentioned? One of my 4.1.11 server 
just hanged with very similar stack trace and I am wondering whether the 
aforementioned patches would help.

Thanks,

Grant

On 23/09/2015 09:31, Eric Dumazet wrote:
> On Wed, 2015-09-23 at 10:25 +0200, Patrick Schaaf wrote:
>> Dear kernel developers,
>>
>> I recently started to upgrade my production hosts and VMs from the 3.14 series
>> to 4.1 kernels, starting with 4.1.6. Yesterday, for the second time after I
>> started these upgrades, I experienced one of our webserver VMs hanging.
>>
>> The first time this happened, the VM hung completely, all 5 virtual cores
>> spinning at 100%, ping still worked, but nothing else, including no virsh
>> console reaction - I had to destroy and restart that VM. No messages were to
>> be found.
>>
>> Yesterday, when it happened the second time, I found the VM spinning on a
>> single core only, and could still connect to it via ssh - but it stopped
>> accepting apache connections. The core it spun on showed 100% time used in
>> "si", with top, and it produced the messages appended below. The VM did not
>> shutdown properly when told to, and had to be destroyed again.
>>
>> If I read that dmesg output correctly it spins in __inet_lookup_established,
>> which indeed reads like it has infinite spin potential. But that code itself
>> did not change relative to the 3.14 series we've been running for a long time
>> without the issues - so the root cause would be something else.
>>
>> For our production systems I'll revert to the 3.14 series, but maybe this
>> report may help somebody understand what's going on.
>>
>> best regards
>>    Patrick
>
>
> You could try following commits :
>
> http://git.kernel.org/cgit/linux/kernel/git/davem/net.git/commit/?id=ed2e923945892a8372ab70d2f61d364b0b6d9054
>
> http://git.kernel.org/cgit/linux/kernel/git/davem/net.git/commit/?id=29c6852602e259d2c1882f320b29d5c3fec0de04
>
>
>
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