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Date: Thu, 1 Jun 2017 13:59:36 +0200
From: Michal Hocko <mhocko@suse.com>
Subject: Re: [PATCH] mm,page_alloc: Serialize warn_alloc() if schedulable.
Message-ID: <20170601115936.GA9091@dhcp22.suse.cz>
References: <1496317427-5640-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp>
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To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: akpm@linux-foundation.org, linux-mm@kvack.org, Cong Wang <xiyou.wangcong@gmail.com>, Dave Hansen <dave.hansen@intel.com>, Johannes Weiner <hannes@cmpxchg.org>, Mel Gorman <mgorman@suse.de>, Vlastimil Babka <vbabka@suse.cz>

On Thu 01-06-17 20:43:47, Tetsuo Handa wrote:
> Cong Wang has reported a lockup when running LTP memcg_stress test [1].

This seems to be on an old and not pristine kernel. Does it happen also
on the vanilla up-to-date kernel?

[...]
> Therefore, this patch uses a mutex dedicated for warn_alloc() like
> suggested in [3].

As I've said previously. We have rate limiting and if that doesn't work
out well, let's tune it. The lock should be the last resort to go with.
We already throttle show_mem, maybe we can throttle dump_stack as well,
although it sounds a bit strange that this adds so much to the picture.

-- 
Michal Hocko
SUSE Labs

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