Re: WARNING in task_participate_group_stop

From: Oleg Nesterov
Date: Mon Nov 02 2015 - 12:10:20 EST

On 11/02, Oleg Nesterov wrote:
> On 11/02, Oleg Nesterov wrote:
> >
> > On 11/02, Dmitry Vyukov wrote:
> > >
> > > But I wasn't able
> > > to figure out what's the root cause (why task does not have
> > > JOBCTL_STOP_PENDING) and maybe the same WARNING can be triggered
> > > without root and/or with other than init process. So still posting it
> > > here.
> >
> > Yes I think you are right. SIGSTOP can race with SIGKILL which (unlike SIGCONT)
> > doesn't clear JOBCTL_STOP_DEQUEUED/PENDING/etc.
> I was wrong... I forgot that complete_signal(SIGKILL) sets SIGNAL_GROUP_EXIT.
> Unless SIGNAL_UNKILLABLE is set, and this is what makes init "special".

and I think this should be fixed anyway, if nothing else to make this logic more
correct. I'll try to recheck this all later.

> So it seems that everything is clear. Except I can't understand why your
> test-case doesn't work for me ;) It should.

Damn. Sorry Dmitry it actually works. Just I didn't see the output from
pr_warn()'s on the serial console due to the wrong console_loglevel.


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