netdev - Re: Soft lockup in inet_put

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Date:   Thu, 08 Dec 2016 22:03:44 +0100
From:   Hannes Frederic Sowa <hannes@...essinduktion.org>
To:     Tom Herbert <tom@...bertland.com>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Josef Bacik <jbacik@...com>
Subject: Re: Soft lockup in inet_put_port on 4.6

Hello Tom,

On Wed, Dec 7, 2016, at 00:06, Tom Herbert wrote:
> We are seeing a fair number of machines getting into softlockup in 4.6
> kernel. As near as I can tell this is happening on the spinlock in
> bind hash bucket. When inet_csk_get_port exits and does spinunlock_bh
> the TCP timer runs and we hit lockup in inet_put_port (presumably on
> same lock). It seems like the locked isn't properly be unlocked
> somewhere but I don't readily see it.
> 
> Any ideas?

Likewise we received reports that pretty much look the same on our
heavily patched kernel. Did you have a chance to investigate or
reproduce the problem?

I am wondering if you would be able to take a complete thread stack dump
if you can reproduce this to check if one of the user space processes is
looping inside finding a free port?

Thanks,
Hannes