linux-kernel - Re: [PATCH v10]: Hibernation: fix the number of pages used for hibernate/thaw buffering

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Message-ID: <4F870317.1030408@debian.org>
Date:	Thu, 12 Apr 2012 18:30:15 +0200
From:	Per Olofsson <pelle@...ian.org>
To:	Bojan Smojver <bojan@...ursive.com>
CC:	"Rafael J. Wysocki" <rjw@...k.pl>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v10]: Hibernation: fix the number of pages used for hibernate/thaw
 buffering

2012-04-12 13:31, Bojan Smojver skrev:
> Bojan Smojver <bojan@...ursive.com> wrote:
> 
>> -	read_pages = (nr_free_pages() - snapshot_get_image_size()) >> 1; 
>> +	read_pages = (low_free_pages() - snapshot_get_image_size()) / 2;
> 
> Actually, I am pretty sure this part of the patch is wrong. Image can
> be bigger than the size of non-high memory. So, this calculation may
> turn up entirely bogus numbers, given we are dealing with unsigned
> values. Sure, we clamp that a line later, so all is not lost, but
> still, it needs to be fixed.

Indeed. I think what you want is:

read_pages = min(low_free_pages(),
                 nr_free_pages() - snapshot_get_image_size()) / 2;

-- 
Pelle
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