Date: Wed, 23 Mar 2005 18:00:31 -0800
From: Andrew Morton <akpm@osdl.org>
To: Andrea Arcangeli <andrea@suse.de>
Cc: mbligh@aracnet.com, aebr@win.tue.nl, cmm@us.ibm.com,
       linux-kernel@vger.kernel.org, ext2-devel@lists.sourceforge.net
Subject: Re: OOM problems on 2.6.12-rc1 with many fsx tests
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Andrea Arcangeli <andrea@suse.de> wrote:
>
> On Wed, Mar 23, 2005 at 03:42:32PM -0800, Andrew Morton wrote:
> > I'm suspecting here that we simply leaked a refcount on every darn
> > pagecache page in the machine.  Note how mapped memory has shrunk down to
> > less than a megabyte and everything which can be swapped out has been
> > swapped out.
> > 
> > If so, then oom-killing everything in the world is pretty inevitable.
> 
> Agreed, it looks like a memleak of a page_count (while mapcount is fine).
> 
> I would suggest looking after pages part of pagecache (i.e.
> page->mapcount not null) that have a mapcount of 0 and a page_count > 1,
> almost all of them should be like that during the memleak, and almost
> none should be like that before the memleak.
> 
> This seems unrelated to the bug that started the thread that was clearly
> a slab shrinking issue and not a pagecache memleak.
> 

The vmscan.c changes in -rc1 look harmless enough.  That's assuming that
2.6.11 doesn't have the bug.

btw, that new orphanned-page handling code has a printk in it, and nobody
has reported it coming out yet...

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