linux-ext4 - Re: possible (ext4 related?) memory leak in kernel 2.6.26

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Message-Id: <200810082355.m98NtZkQ012577@goelette.ens.fr>
Date:	Thu, 9 Oct 2008 01:52:46 +0200
From:	Quentin Godfroy <godfroy@...pper.ens.fr>
To:	Theodore Tso <tytso@....edu>, Eric Sandeen <sandeen@...hat.com>,
	linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: possible (ext4 related?) memory leak in kernel 2.6.26

On Tue, Oct 07, 2008 at 08:53:38PM -0400, Theodore Tso wrote:
> On Wed, Oct 08, 2008 at 02:02:27AM +0200, Quentin Godfroy wrote:
> > 
> > I rebooted, but as I didn't know exactly how to trigger the bug except than
> > by waiting a few days I was waiting to see.
> > 
> > Do you have an idea about how to trigger the bug?
> 
> The bug is that each time a transaction commits, if the buffer head
> hasn't been leaked already, it will leak pinning the memory until the
> total size of the journal is taking up memory.  If you have a 2gigs of
> memory, and a single filesystem with 256meg journal, you might not
> notice the problem at all.  If you less than 256 megs of memory,
> you'll notice fairly quickly.   

Indeed after a couple of days of uptime the number of dirty blocks do not go
further than ~50, so I think the bug is corrected as far as I am concerned.

By the way, why does the kernel not commit to memory these remaining buffers
when the memory is scarse (say instead of firing an OOM killer)?

Regards
Quentin Godfroy
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