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Date: Wed, 20 Jul 2011 08:54:10 -0500 (CDT)
From: Christoph Lameter <cl@linux.com>
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To: Pekka Enberg <penberg@kernel.org>
cc: Konstantin Khlebnikov <khlebnikov@parallels.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Matt Mackall <mpm@selenic.com>, "mgorman@suse.de" <mgorman@suse.de>
Subject: Re: [PATCH] mm-slab: allocate kmem_cache with __GFP_REPEAT
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On Wed, 20 Jul 2011, Pekka Enberg wrote:

> On Wed, 20 Jul 2011, Konstantin Khlebnikov wrote:
> > > The changelog isn't that convincing, really. This is kmem_cache_create()
> > > so I'm surprised we'd ever get NULL here in practice. Does this fix some
> > > problem you're seeing? If this is really an issue, I'd blame the page
> > > allocator as GFP_KERNEL should just work.
> >
> > nf_conntrack creates separate slab-cache for each net-namespace,
> > this patch of course not eliminates the chance of failure, but makes it more
> > acceptable.
>
> I'm still surprised you are seeing failures. mm/slab.c hasn't changed
> significantly in a long time. Why hasn't anyone reported this before? I'd
> still be inclined to shift the blame to the page allocator... Mel, Christoph?

There was a lot of recent fiddling with the reclaim logic. Maybe some of
those changes caused the problem?