linux-ext4 - Re: [PATCH] PM / Freezer: Freeze filesystems while freezing processes (v2)

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Date:	Wed, 16 Nov 2011 14:49:23 +0100
From:	Ferenc Wagner <wferi@...f.hu>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Christoph <cr2005@...lub.de>, "Theodore Ts'o" <tytso@....edu>,
	LKML <linux-kernel@...r.kernel.org>, xfs@....sgi.com,
	Christoph Hellwig <hch@...radead.org>,
	Nigel Cunningham <nigel@...onice.net>,
	Pavel Machek <pavel@....cz>, linux-fsdevel@...r.kernel.org,
	linux-ext4@...r.kernel.org,
	Linux PM list <linux-pm@...r.kernel.org>
Subject: Re: [PATCH] PM / Freezer: Freeze filesystems while freezing processes (v2)

"Rafael J. Wysocki" <rjw@...k.pl> writes:

> On Saturday, October 22, 2011, Christoph wrote:
>
>>> PM / Freezer: Freeze filesystems while freezing processes (v2)
>>> 
>>> On Sunday, August 07, 2011, Dave Chinner wrote:
>>>
>>>> On Sat, Aug 06, 2011 at 11:17:18PM +0200, Rafael J. Wysocki wrote:
>>>>
>>>>> From: Rafael J. Wysocki <rjw@...k.pl>
>>>>> 
>>>>> Freeze all filesystems during the freezing of tasks by calling 
>>>>> freeze_bdev() for each of them and thaw them during the thawing of
>>>>> tasks with the help of thaw_bdev().
>>>>> 
>>>>> This is needed by hibernation, because some filesystems (e.g. XFS) 
>>>>> deadlock with the preallocation of memory used by it if the memory 
>>>>> pressure caused by it is too heavy.
>>>
>>> Below is an alternative fix, the changelog pretty much explains the
>>> idea.
>>> 
>>> I've tested it on Toshiba Portege R500, but I don't have an XFS
>>> partition to verify that it really helps, so I'd appreciate it if
>>> someone able to reproduce the original issue could test it and report
>>> back.
>> 
>> Well, the kernel bugtracker is still down and I just like to post my
>> experience with kernel (x64) v3.1-rc8/9 + patches. My machine is a
>> MacBookPro, doomed with 4GB RAM running debian.
>> 
>> Bug #1
>> 
>> on the way to hibernate, machine hangs on
>> 
>> "PM: Preallocating image memory..."
>> 
>> this patch worked for me now for weeks:
>> "[PATCH] PM / Freezer: Freeze filesystems while freezing processes (v2)"
>> https://lkml.org/lkml/2011/9/24/77
>
> This patch is going to be merged into 3.2.

Hi,

I was the original reporter of the Bugzilla issue, just didn't know
about this thread until recently.  Anyway, I'm running 3.2-rc1 now,
which contains the alternative fix, and I can confirm that it indeed
works: hibernation does not deadlock on my XFS rooted system anymore
during memory preallocation.  Thanks everybody for his or her work on
the issue!

To add something still, preallocation now ends with a couple of seconds
of heavy disk activity, but with several seconds of total inactivity
beforehand.  Is this warranted by some CPU intensive task at that stage?
-- 
Thanks,
Feri.
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