From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Oliver Neukum <oliver@neukum.org>
Subject: Re: [RFC][PATCH] PM: Force GFP_NOIO during suspend/resume (was: Re: [linux-pm] Memory allocations in .suspend became very unreliable)
Date: Wed, 20 Jan 2010 22:13:23 +0100
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Cc: Maxim Levitsky <maximlevitsky@gmail.com>,
       linux-pm@lists.linux-foundation.org,
       LKML <linux-kernel@vger.kernel.org>, "linux-mm" <linux-mm@kvack.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       Benjamin Herrenschmidt <benh@kernel.crashing.org>
References: <1263549544.3112.10.camel@maxim-laptop> <201001192137.35232.rjw@sisk.pl> <201001201505.41167.oliver@neukum.org>
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On Wednesday 20 January 2010, Oliver Neukum wrote:
> 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

That was tried, didn't work.

> b) set the ration of clean pages to dirty pages to 0 while suspending
> the system.

Patch, please?

Rafael
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