linux-kernel - Re: thousands of kworker processes with 4.7.x and 4.8-rc*

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Date:   Fri, 23 Sep 2016 16:10:00 +0200
From:   Mike Galbraith <umgwanakikbuti@...il.com>
To:     Tomasz Chmielewski <mangoo@...g.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: thousands of kworker processes with 4.7.x and 4.8-rc*

On Fri, 2016-09-23 at 22:23 +0900, Tomasz Chmielewski wrote:
> On 2016-09-19 16:08, Tomasz Chmielewski wrote:
> > On several servers running 4.7.x and 4.8-rc6/7 kernels I'm seeing
> > thousands of kworker processes.
> > # ps auxf|grep -c kworker
> > 2104
> > Load average goes into hundreds on a pretty much idle server (biggest
> > CPU and RAM consumers are probably SSHD with one user logged in and
> > rsyslog writing ~1 line per minute):
> > # uptime
> >  06:58:56 up 26 min,  1 user,  load average: 146.11, 215.46, 105.70
> > # uptime
> >  06:59:48 up 26 min,  1 user,  load average: 305.20, 240.84, 120.25
> > Sometimes seeing lots of them in "D" state:
> > root     19474  0.0  0.0      0     0 ?        D    06:54   0:00  \_
> > [kworker/0:208]
> > root     19475  0.0  0.0      0     0 ?        D    06:54   0:00  \_
> > [kworker/0:209]
> 
> 
> I did some experiments to see when the problem first appeared. Thousands 
> of kworker processes start to show up in 4.7.0-rc5.
> 
> kernel version | kworker count after boot
> -------------------------------------------
> 4.6.3 > 	>         37
> 4.6.4 > 	>         47
> 4.6.5 > 	>         46
> 4.6.6 > 	>         49
> 4.6.7 > 	>         49
> 4.7.0-rc1 > 	> 46
> 4.7.0-rc2 > 	> 49
> 4.7.0-rc3> 	> 45
> 4.7.0-rc4> 	> 47
> 4.7.0-rc5> 	> 1592

Best bet would be to use 'git bisect' to locate the exact commit that
caused this, and post the bisection result along with your config.

AFAIK, nobody else is seeing this, is the kernel virgin source?

	-Mike