From: Michal Hocko <mhocko@kernel.org>
To: Christoph Lameter <cl@linux.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Mel Gorman <mgorman@techsingularity.net>,
Vlastimil Babka <vbabka@suse.cz>,
Dmitry Vyukov <dvyukov@google.com>, Tejun Heo <tj@kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
syzkaller <syzkaller@googlegroups.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: mm: deadlock between get_online_cpus/pcpu_alloc
Date: Wed, 8 Feb 2017 16:21:07 +0100 [thread overview]
Message-ID: <20170208152106.GP5686@dhcp22.suse.cz> (raw)
In-Reply-To: <alpine.DEB.2.20.1702080906540.3955@east.gentwo.org>
On Wed 08-02-17 09:11:06, Cristopher Lameter wrote:
> On Wed, 8 Feb 2017, Michal Hocko wrote:
>
> > > Huch? stop_machine() is horrible and heavy weight. Don't go there, there
> > > must be simpler solutions than that.
> >
> > Absolutely agreed. We are in the page allocator path so using the
> > stop_machine* is just ridiculous. And, in fact, there is a much simpler
> > solution [1]
>
> That is nonsense. stop_machine would be used when adding removing a
> processor. There would be no need to synchronize when looping over active
> cpus anymore. get_online_cpus() etc would be removed from the hot
> path since the cpu masks are guaranteed to be stable.
I have no idea what you are trying to say and how this is related to the
deadlock we are discussing here. We certainly do not need to add
stop_machine the problem. And yeah, dropping get_online_cpus was
possible after considering all fallouts.
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2017-02-08 15:21 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-29 12:44 mm: deadlock between get_online_cpus/pcpu_alloc Dmitry Vyukov
2017-01-29 17:22 ` Vlastimil Babka
2017-01-30 15:48 ` Dmitry Vyukov
2017-02-06 19:13 ` Dmitry Vyukov
2017-02-06 22:05 ` Mel Gorman
2017-02-07 8:48 ` Michal Hocko
2017-02-07 9:23 ` Vlastimil Babka
2017-02-07 9:46 ` Mel Gorman
2017-02-07 9:53 ` Michal Hocko
2017-02-07 10:42 ` Mel Gorman
2017-02-07 11:13 ` Mel Gorman
2017-02-07 9:43 ` Mel Gorman
2017-02-07 9:49 ` Vlastimil Babka
2017-02-07 10:05 ` Michal Hocko
2017-02-07 10:28 ` Mel Gorman
2017-02-07 10:35 ` Michal Hocko
2017-02-07 11:34 ` Mel Gorman
2017-02-07 11:43 ` Michal Hocko
2017-02-07 11:54 ` Vlastimil Babka
2017-02-07 12:08 ` Michal Hocko
2017-02-07 12:37 ` Michal Hocko
2017-02-07 12:43 ` Vlastimil Babka
2017-02-07 12:48 ` Michal Hocko
2017-02-07 13:57 ` Vlastimil Babka
2017-02-07 13:58 ` Mel Gorman
2017-02-07 14:19 ` Michal Hocko
2017-02-07 15:34 ` Michal Hocko
2017-02-07 16:22 ` Mel Gorman
2017-02-07 16:41 ` Michal Hocko
2017-02-07 16:55 ` Christoph Lameter
2017-02-07 22:25 ` Thomas Gleixner
2017-02-08 7:35 ` Michal Hocko
2017-02-08 12:02 ` Thomas Gleixner
2017-02-08 12:21 ` Michal Hocko
2017-02-08 12:26 ` Mel Gorman
2017-02-08 13:23 ` Thomas Gleixner
2017-02-08 14:03 ` Mel Gorman
2017-02-08 14:11 ` Peter Zijlstra
2017-02-08 15:11 ` Christoph Lameter
2017-02-08 15:21 ` Michal Hocko [this message]
2017-02-08 16:17 ` Christoph Lameter
2017-02-08 17:46 ` Thomas Gleixner
2017-02-09 3:15 ` Christoph Lameter
2017-02-09 11:42 ` Thomas Gleixner
2017-02-09 14:00 ` Christoph Lameter
2017-02-09 14:53 ` Thomas Gleixner
2017-02-09 15:42 ` Christoph Lameter
2017-02-09 16:12 ` Thomas Gleixner
2017-02-09 17:22 ` Christoph Lameter
2017-02-09 17:40 ` Thomas Gleixner
2017-02-09 19:15 ` Michal Hocko
2017-02-10 17:58 ` Christoph Lameter
2017-02-08 15:06 ` Christoph Lameter
2017-02-07 17:03 ` Tejun Heo
2017-02-07 20:16 ` Michal Hocko
2017-02-07 13:03 ` Mel Gorman
2017-02-07 13:48 ` Michal Hocko
2017-02-07 11:24 ` Tetsuo Handa
2017-02-07 8:43 ` Michal Hocko
2017-02-07 21:53 ` Thomas Gleixner
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