linux-kernel - Re: [PATCH v8]: Hibernation: lower/better control the amount of pages used for buffering

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Date:	Tue, 10 Apr 2012 12:25:54 +1000
From:	Bojan Smojver <bojan@...ursive.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	linux-kernel@...r.kernel.org,
	Linux PM list <linux-pm@...r.kernel.org>,
	Per Olofsson <pelle@...ian.org>
Subject: Re: [PATCH v8]: Hibernation: lower/better control the amount of
 pages used for buffering

On Sun, 2012-04-08 at 10:14 +1000, Bojan Smojver wrote:
> Please ignore this request. As it turns out, the hangs are still
> there, it just takes a bit longer to trigger.

Thanks to Per Olofsson, who actually determined what was going on, we
now know what the problem is.

My "free pages" maths used nr_free_pages() macro, which deals with all
free pages. However, we only allocate buffers from non-high zones. So,
on systems where there is a significant number of high pages free, we
get a very large number (even if only a quarter is used), which then
gets the kernel into a bind and eventually hangs it on page allocation.

Will send a patch shortly, which will also have some other fixes.

-- 
Bojan

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