linux-kernel - Re: [PATCH] oom: add sysctl to enable slab memory dump

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Message-ID: <alpine.DEB.2.00.1202241550080.2401@chino.kir.corp.google.com>
Date:	Fri, 24 Feb 2012 15:51:50 -0800 (PST)
From:	David Rientjes <rientjes@...gle.com>
To:	Pekka Enberg <penberg@...nel.org>
cc:	Josef Bacik <josef@...hat.com>, Rafael Aquini <aquini@...hat.com>,
	linux-mm@...ck.org, Randy Dunlap <rdunlap@...otime.net>,
	Christoph Lameter <cl@...ux-foundation.org>,
	Matt Mackall <mpm@...enic.com>, Rik van Riel <riel@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] oom: add sysctl to enable slab memory dump

On Fri, 24 Feb 2012, Pekka Enberg wrote:

> On Fri, 24 Feb 2012, Josef Bacik wrote:
> >> Um well yeah, I'm rewriting a chunk of btrfs which was rapantly leaking memory
> >> so the OOM just couldn't keep up with how much I was sucking down.  This is
> >> strictly a developer is doing something stupid and needs help pointing out what
> >> it is sort of moment, not a day to day OOM.
> 
> On Fri, Feb 24, 2012 at 11:45 PM, David Rientjes <rientjes@...gle.com> wrote:
> > If you're debugging new kernel code and you realize that excessive amount
> > of memory is being consumed so that nothing can even fork, you may want to
> > try cat /proc/slabinfo before you get into that condition the next time
> > around, although I already suspect that you know the cache you're leaking.
> > It doesn't mean we need to add hundreds of lines of code to the kernel.
> > Try kmemleak.
> 
> Kmemleak is a wonderful tool but it's also pretty heavy-weight which
> makes it inconvenient in many cases.
> 

Too heavyweight to enable when debugging issues after "rewriting a chunk" 
of a filesystem that manipulates kernel memory?  I can't imagine a better 
time to enable it.