From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Mel Gorman <mgorman@suse.de>
Cc: Linux-MM <linux-mm@kvack.org>,
Linux-FSDevel <linux-fsdevel@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>,
Russell King - ARM Linux <linux@arm.linux.org.uk>,
Gilad Ben-Yossef <gilad@benyossef.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Miklos Szeredi <mszeredi@novell.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Greg KH <gregkh@suse.de>, Gong Chen <gong.chen@intel.com>
Subject: Re: [PATCH 2/2] mm: page allocator: Do not drain per-cpu lists via IPI from page allocator context
Date: Thu, 12 Jan 2012 16:52:31 +0100 [thread overview]
Message-ID: <1326383551.2442.203.camel@twins> (raw)
In-Reply-To: <20120112153712.GL4118@suse.de>
On Thu, 2012-01-12 at 15:37 +0000, Mel Gorman wrote:
> On Thu, Jan 12, 2012 at 04:18:12PM +0100, Peter Zijlstra wrote:
> > On Wed, 2012-01-11 at 10:11 +0000, Mel Gorman wrote:
> > > At least one bug report has
> > > been seen on ppc64 against a 3.0 era kernel that looked like a bug
> > > receiving interrupts on a CPU being offlined.
> >
> > Got details on that Mel? The preempt_disable() in on_each_cpu() should
> > serialize against the stop_machine() crap in unplug.
>
> I might have added 2 and 2 together and got 5.
>
> The stack trace clearly was while sending IPIs in on_each_cpu() and
> always when under memory pressure and stuck in direct reclaim. This was
> on !PREEMPT kernels where preempt_disable() is a no-op. That is why I
> thought get_online_cpu() would be necessary.
For non-preempt the required scheduling of stop_machine() will have to
wait even longer. Still there might be something funny, some of the
hotplug notifiers are ran before the stop_machine thing does its thing
so there might be some fun interaction.
next prev parent reply other threads:[~2012-01-12 15:52 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-11 10:11 [RFC PATCH 0/2] Improve reliability of CPU hotplug Mel Gorman
2012-01-11 10:11 ` [PATCH 1/2] fs: sysfs: Do dcache-related updates to sysfs dentries under sysfs_mutex Mel Gorman
2012-01-11 17:11 ` Eric W. Biederman
2012-01-11 18:07 ` Mel Gorman
2012-01-11 19:02 ` Eric W. Biederman
2012-01-11 10:11 ` [PATCH 2/2] mm: page allocator: Do not drain per-cpu lists via IPI from page allocator context Mel Gorman
2012-01-12 14:51 ` Gilad Ben-Yossef
2012-01-12 15:08 ` Peter Zijlstra
2012-01-12 15:13 ` Gilad Ben-Yossef
2012-01-12 15:08 ` Gilad Ben-Yossef
2012-01-12 15:18 ` Peter Zijlstra
2012-01-12 15:37 ` Mel Gorman
2012-01-12 15:52 ` Peter Zijlstra [this message]
2012-01-12 17:18 ` Mel Gorman
2012-01-12 19:14 ` Gilad Ben-Yossef
[not found] ` <no-drain-reply@mdm.bga.com>
[not found] ` <20120119162057.GD3143@suse.de>
2012-01-19 21:46 ` Srivatsa S. Bhat
2012-01-20 8:48 ` Mel Gorman
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