linux-kernel - Re: [RFC][PATCH] PM: Force GFP_NOIO during suspend/resume (was: Re: [linux-pm] Memory allocations in .suspend became very unreliable)

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Message-Id: <201001201505.41167.oliver@neukum.org>
Date:	Wed, 20 Jan 2010 15:05:41 +0100
From:	Oliver Neukum <oliver@...kum.org>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Maxim Levitsky <maximlevitsky@...il.com>,
	linux-pm@...ts.linux-foundation.org,
	LKML <linux-kernel@...r.kernel.org>,
	"linux-mm" <linux-mm@...ck.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Subject: Re: [RFC][PATCH] PM: Force GFP_NOIO during suspend/resume (was: Re: [linux-pm] Memory allocations in .suspend became very unreliable)

Am Dienstag, 19. Januar 2010 21:37:35 schrieb Rafael J. Wysocki:
> That said, Maxim reported that in his test case the mm subsystem apparently
> attempted to use I/O even if there was a plenty of free memory available and
> I'd like prevent that from happening.

Hi,

it seems to me that this is caused by the mm subsytem maintaing
a share of clean pages precisely so that GFP_NOIO will work.
Perhaps it is a good idea to
a) launder a number of pages if the system is about to be suspended
between the freezer and notifying drivers
b) set the ration of clean pages to dirty pages to 0 while suspending
the system.

	Regards
		Oliver
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