Re: workqueue: WARN at at kernel/workqueue.c:2176

[Sasha Levin <sasha.levin@oracle.com>]

On 05/12/2014 10:19 PM, Lai Jiangshan wrote:
> On 05/13/2014 04:01 AM, Tejun Heo wrote:
>> > On Mon, May 12, 2014 at 02:58:55PM -0400, Sasha Levin wrote:
>>> >> Hi all,
>>> >>
>>> >> While fuzzing with trinity inside a KVM tools guest running the latest -next
>>> >> kernel I've stumbled on the following spew:
>>> >>
>>> >> [ 1297.886670] WARNING: CPU: 0 PID: 190 at kernel/workqueue.c:2176 process_one_work+0xb5/0x6f0()
>>> >> [ 1297.889216] Modules linked in:
>>> >> [ 1297.890306] CPU: 0 PID: 190 Comm: kworker/3:0 Not tainted 3.15.0-rc5-next-20140512-sasha-00019-ga20bc00-dirty #456
>>> >> [ 1297.893258]  0000000000000009 ffff88010c5d7ce8 ffffffffb153e1ec 0000000000000002
>>> >> [ 1297.893258]  0000000000000000 ffff88010c5d7d28 ffffffffae15fd6c ffff88010cdd6c98
>>> >> [ 1297.893258]  ffff8806285d4000 ffffffffb3cd09e0 ffff88010cdde000 0000000000000000
>>> >> [ 1297.893258] Call Trace:
>>> >> [ 1297.893258] dump_stack (lib/dump_stack.c:52)
>>> >> [ 1297.893258] warn_slowpath_common (kernel/panic.c:430)
>>> >> [ 1297.893258] warn_slowpath_null (kernel/panic.c:465)
>>> >> [ 1297.893258] process_one_work (kernel/workqueue.c:2174 (discriminator 38))
>>> >> [ 1297.893258] worker_thread (kernel/workqueue.c:2354)
>>> >> [ 1297.893258] kthread (kernel/kthread.c:210)
>>> >> [ 1297.893258] ret_from_fork (arch/x86/kernel/entry_64.S:553)
> Hi,
> 
> I have been trying to address this bug.
> Buy I can't reproduce this bug. Is your testing arch X86?
> if yes, could you find out how to reproduce the bug?

Yup, it's a 64bit KVM guest.

I don't have an easy way to reproduce it as I only saw the bug once, but
it happened when I started pressuring CPU hotplug paths by adding and removing
CPUs often. Maybe it has anything to do with that?


Thanks,
Sasha