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From: Heiko Carstens <heiko.carstens@de.ibm.com>
To: Tejun Heo <tj@kernel.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>,
	Peter Zijlstra <peterz@infradead.org>,
	"linux-kernel@vger.kernel.org >> Linux Kernel Mailing List" 
	<linux-kernel@vger.kernel.org>,
	linux-s390 <linux-s390@vger.kernel.org>,
	KVM list <kvm@vger.kernel.org>, Oleg Nesterov <oleg@redhat.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: Re: regression 4.4: deadlock in with cgroup percpu_rwsem
Date: Wed, 20 Jan 2016 08:07:40 +0100	[thread overview]
Message-ID: <20160120070740.GA3395@osiris> (raw)
In-Reply-To: <20160119193845.GT3520@mtj.duckdns.org>

On Tue, Jan 19, 2016 at 02:38:45PM -0500, Tejun Heo wrote:
> Hello,
> 
> On Tue, Jan 19, 2016 at 08:36:18PM +0100, Christian Borntraeger wrote:
> > No, its not a task_struct. Activating some more debug information did indeed 
> > revealed several other issues (overwritten redzones etc). Unfortunately I 
> > only saw the broken things after the facts, so I do not know which code did that.
> > When I disabled the cgroup controllers in libvirt I was no longer able to trigger
> > the bugs. Still trying to narrow things down.
> 
> Hmmm... that's worrying.  CONFIG_DEBUG_PAGEALLOC sometimes can catch
> these sort of bugs red-handed.  Might worth trying.

Christian, just to avoid that you get surprised like I did:
CONFIG_DEBUG_PAGEALLOC requires in the meantime an additional kernel
parameter "debug_pagealloc=on" to be active.

That change was introduced a year ago, so it was probably only me who
wasn't aware of that change :)

  reply	other threads:[~2016-01-20  7:08 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-14 11:19 regression 4.4: deadlock in with cgroup percpu_rwsem Christian Borntraeger
2016-01-14 13:38 ` Christian Borntraeger
2016-01-14 14:04 ` Nikolay Borisov
2016-01-14 14:08   ` Christian Borntraeger
2016-01-14 14:27     ` Nikolay Borisov
2016-01-14 17:15       ` Christian Borntraeger
2016-01-14 19:56 ` Tejun Heo
2016-01-15  7:30   ` Christian Borntraeger
2016-01-15 15:13     ` Christian Borntraeger
2016-01-18 18:32       ` Peter Zijlstra
2016-01-18 18:48         ` Christian Borntraeger
2016-01-19  9:55           ` Heiko Carstens
2016-01-19 19:36             ` Christian Borntraeger
2016-01-19 19:38               ` Tejun Heo
2016-01-20  7:07                 ` Heiko Carstens [this message]
2016-01-20 10:15                   ` Christian Borntraeger
2016-01-20 10:30                     ` Peter Zijlstra
2016-01-20 10:47                       ` Peter Zijlstra
2016-01-20 15:30                         ` Tejun Heo
2016-01-20 16:04                           ` Tejun Heo
2016-01-20 16:49                             ` Peter Zijlstra
2016-01-20 16:56                               ` Tejun Heo
2016-01-23  2:03                           ` Paul E. McKenney
2016-01-25  8:49                             ` Christoph Hellwig
2016-01-25 19:38                               ` Tejun Heo
2016-01-26 14:51                                 ` Christoph Hellwig
2016-01-26 15:28                                   ` Tejun Heo
2016-01-26 16:41                                     ` Christoph Hellwig
2016-01-20 10:53                       ` Peter Zijlstra
2016-01-21  8:23                         ` Christian Borntraeger
2016-01-21  9:27                           ` Peter Zijlstra
2016-01-15 16:40     ` Tejun Heo
2016-01-19 17:18       ` [PATCH cgroup/for-4.5-fixes] cpuset: make mm migration asynchronous Tejun Heo
2016-01-22 14:24         ` Christian Borntraeger
2016-01-22 15:22           ` Tejun Heo
2016-01-22 15:45             ` Christian Borntraeger
2016-01-22 15:47               ` Tejun Heo
2016-01-22 15:23         ` Tejun Heo
2016-01-21 20:31     ` [PATCH 1/2] cgroup: make sure a parent css isn't offlined before its children Tejun Heo
2016-01-21 20:32       ` [PATCH 2/2] cgroup: make sure a parent css isn't freed " Tejun Heo
2016-01-22 15:45         ` [PATCH v2 " Tejun Heo
2016-01-21 21:24       ` [PATCH 1/2] cgroup: make sure a parent css isn't offlined " Peter Zijlstra
2016-01-21 21:28         ` Tejun Heo
2016-01-22  8:18           ` Christian Borntraeger
2016-02-29 11:13         ` [tip:sched/core] sched/cgroup: Fix cgroup entity load tracking tear-down tip-bot for Peter Zijlstra
2016-01-22 15:45       ` [PATCH v2 1/2] cgroup: make sure a parent css isn't offlined before its children Tejun Heo

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