From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3x22vF2Yx0zDqj1 for ; Tue, 4 Jul 2017 22:12:41 +1000 (AEST) Date: Tue, 4 Jul 2017 20:12:36 +0800 From: Eryu Guan To: Michael Ellerman Cc: tj@kernel.org, Balbir Singh , liwan@redhat.com, "open list:LINUX FOR POWERPC (32-BIT AND 64-BIT)" Subject: Re: kworker with empty task->cpus_allowed (was Re: [v4.12-rc1 regression] mount ext4 fs results in kernel crash on PPC64le host) Message-ID: <20170704121236.GO23360@eguan.usersys.redhat.com> References: <20170629100533.GQ23360@eguan.usersys.redhat.com> <87efu39he0.fsf@concordia.ellerman.id.au> <20170629113933.GT23360@eguan.usersys.redhat.com> <878tkb9ewo.fsf@concordia.ellerman.id.au> <20170629135919.GU23360@eguan.usersys.redhat.com> <8760fdrdq1.fsf@concordia.ellerman.id.au> <20170630114756.GD23360@eguan.usersys.redhat.com> <87tw2syayk.fsf@concordia.ellerman.id.au> <20170704082101.GM23360@eguan.usersys.redhat.com> <87r2xwxxyo.fsf@concordia.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <87r2xwxxyo.fsf@concordia.ellerman.id.au> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, Jul 04, 2017 at 09:06:55PM +1000, Michael Ellerman wrote: > Eryu Guan writes: > > > On Tue, Jul 04, 2017 at 04:26:11PM +1000, Michael Ellerman wrote: > >> Eryu Guan writes: > >> > On Fri, Jun 30, 2017 at 08:07:02PM +1000, Michael Ellerman wrote: > >> >> > >> >> Can you try this patch and see if it changes anything? (with the debug > >> >> still applied). > >> > > >> > This patch fixes the crash for me. After appliying this patch (with all > >> > other debug patches still applied), kernel didn't print any warnings or > >> > calltraces or debug messages. > >> > >> OK. It's not meant to fix it :) > > > > Understand. > > > >> > >> I can't form any connection between your bisection result and that > >> patch, nothing is making any sense TBH. > >> > >> What hardware are you on? And are you doing CPU hotplug or anything like that? > > > > It's a "PowerVM" guest (I'm not familiar with powerpc, I don't know what > > does that mean..) running on Power8 host. I didn't do any CPU hotplug or > > anything like that. > > OK thanks. > > We might have to try and sync up on irc so we can debug this a bit faster. Sure, where can I find you? I'm in #xfs at freenode, nick eguan. But maybe tomorrow, I have to take off today. > > Can you try this hunk also? This new WARN_ON didn't trigger (I skipped the other warning messages, they're the same warnings as in my last reply). Thanks, Eryu > > cheers > > diff --git a/kernel/workqueue.c b/kernel/workqueue.c > index c74bf39ef764..7c55721b1f1d 100644 > --- a/kernel/workqueue.c > +++ b/kernel/workqueue.c > @@ -3902,6 +3906,7 @@ static int alloc_and_link_pwqs(struct workqueue_struct *wq) > "ordering guarantee broken for workqueue %s\n", wq->name); > return ret; > } else { > + WARN_ON(cpumask_empty(unbound_std_wq_attrs[highpri]->cpumask)); > return apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]); > } > } > >