linux-kernel - Re: [BUGFIX][PATCH] vmscan: don't use return value trick when oom_killer

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Message-ID: <AANLkTinxHbeCUh80i515FPMpF-GY4S0kh9PHqUNtYP-m@mail.gmail.com>
Date:	Wed, 1 Sep 2010 11:01:43 +0900
From:	Minchan Kim <minchan.kim@...il.com>
To:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc:	Johannes Weiner <hannes@...xchg.org>,
	Rik van Riel <riel@...hat.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	"M. Vefa Bicakci" <bicave@...eronline.com>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [BUGFIX][PATCH] vmscan: don't use return value trick when oom_killer_disabled

On Wed, Sep 1, 2010 at 10:55 AM, KOSAKI Motohiro
<kosaki.motohiro@...fujitsu.com> wrote:
> Hi
>
> Thank you for good commenting!
>
>
>> I don't like use oom_killer_disabled directly.
>> That's because we have wrapper inline functions to handle the
>> variable(ex, oom_killer_[disable/enable]).
>> It means we are reluctant to use the global variable directly.
>> So should we make new function as is_oom_killer_disable?
>>
>> I think NO.
>>
>> As I read your description, this problem is related to only hibernation.
>> Since hibernation freezes all processes(include kswapd), this problem
>> happens. Of course, now oom_killer_disabled is used by only
>> hibernation. But it can be used others in future(Off-topic : I don't
>> want it). Others can use it without freezing processes. Then kswapd
>> can set zone->all_unreclaimable and the problem can't happen.
>>
>> So I want to use sc->hibernation_mode which is already used
>> do_try_to_free_pages instead of oom_killer_disabled.
>
> Unfortunatelly, It's impossible. shrink_all_memory() turn on
> sc->hibernation_mode. but other hibernation caller merely call
> alloc_pages(). so we don't have any hint.
>
Ahh.. True. Sorry for that.
I will think some better method.
if I can't find it, I don't mind this patch. :)

Thanks.


-- 
Kind regards,
Minchan Kim
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