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From: Yafang Shao <laoar.shao@gmail.com>
Date: Mon, 27 Nov 2017 16:54:39 +0800
Message-ID: <CALOAHbD+ab=1=9w=1ikGYhft-s3BU5Ro=ugCDS2GaJ6b90JQgA@mail.gmail.com>
Subject: Re: [PATCH] mm: print a warning once the vm dirtiness settings is illogical
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Sender: owner-linux-mm@kvack.org
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To: Michal Hocko <mhocko@suse.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>, Andrew Morton <akpm@linux-foundation.org>, Jan Kara <jack@suse.cz>, Linux MM <linux-mm@kvack.org>, fcicq@fcicq.net

2017-11-27 16:52 GMT+08:00 Michal Hocko <mhocko@suse.com>:
> On Mon 27-11-17 16:49:34, Yafang Shao wrote:
>> 2017-11-27 16:37 GMT+08:00 Michal Hocko <mhocko@suse.com>:
>> > On Mon 27-11-17 16:32:42, Yafang Shao wrote:
>> >> 2017-11-27 16:29 GMT+08:00 Yafang Shao <laoar.shao@gmail.com>:
> [...]
>> >> > It will help us to find the error if we don't change these values like this.
>> >> >
>> >>
>> >> And actually it help us find another issue that when availble_memroy
>> >> is too small, the thresh and bg_thresh will be 0, that's absolutely
>> >> wrong.
>> >
>> > Why is it wrong?
>> > --
>>
>> For example, the writeback threads will be wakeup on every write.
>> I don't think it is meaningful to wakeup the writeback thread when the
>> dirty pages is very low.
>
> Well, this is a corner situation when we are out of memory basically.
> Doing a wake up on the flusher is the least of your problem. So _why_
> exactly is this is problem?
> --

Are you _sure_ this is the least of  the problem on this corner situation ?
Why wakeup the bdi writeback ? why not just kill the program and flush
the date into the Disk when we do oom ?

Thanks
Yafang

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