linux-kernel - Re: [Bug 9182] Critical memory leak (dirty pages)

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Date:	Mon, 17 Dec 2007 15:26:22 +0100
From:	Jan Kara <jack@...e.cz>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Krzysztof Oledzki <olel@....pl>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Nick Piggin <nickpiggin@...oo.com.au>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Osterried <osterried@...se.de>, protasnb@...il.com,
	bugme-daemon@...zilla.kernel.org
Subject: Re: [Bug 9182] Critical memory leak (dirty pages)

> On Sun, 16 Dec 2007 14:46:36 +0100 (CET) Krzysztof Oledzki <olel@....pl> wrote:
> 
> > >>> Which filesystem, which mount options
> > >>
> > >>   - ext3 on RAID1 (MD): / - rootflags=data=journal
> > >
> > > It wouldn't surprise me if this is specific to data=journal: that
> > > journalling mode is pretty complex wrt dairty-data handling and isn't well
> > > tested.
> > >
> > > Does switching that to data=writeback change things?
> > 
> > I'll confirm this tomorrow but it seems that even switching to 
> > data=ordered (AFAIK default o ext3) is indeed enough to cure this problem.
> 
> yes, sorry, I meant ordered.
> 
> > Two questions remain then: why system dies when dirty reaches ~200MB 
> 
> I think you have ~2G of RAM and you're running with 
> /proc/sys/vm/dirty_ratio=10, yes?
> 
> If so, when that machine hits 10% * 2G of dirty memory then everyone who
> wants to dirty pages gets blocked.
> 
> > and what is wrong with ext3+data=journal with >=2.6.20-rc2?
> 
> Ah.  It has a bug in it ;)
> 
> As I said, data=journal has exceptional handling of pagecache data and is
> not well tested.  Someone (and I'm not sure who) will need to get in there
> and fix it.
  It seems fsx-linux is able to trigger the leak on my test machine so
I'll have a look into it (not sure if I'll get to it today but I should
find some time for it this week)...

									Honza
-- 
Jan Kara <jack@...e.cz>
SuSE CR Labs
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