Re: [patch 1/3] mm: SLUB fix reclaim_state

[Nick Piggin <npiggin@suse.de>]

On Wed, May 06, 2009 at 10:20:30AM +0300, Pekka Enberg wrote:
> On Tue, 2009-05-05 at 19:13 +1000, npiggin@suse.de wrote:
> > plain text document attachment (mm-slub-fix-reclaim_state.patch)
> > SLUB does not correctly account reclaim_state.reclaimed_slab, so it will
> > break memory reclaim. Account it like SLAB does.
> > 
> > Cc: stable@kernel.org
> > Cc: linux-mm@kvack.org
> > Cc: Pekka Enberg <penberg@cs.helsinki.fi>
> > Cc: Matt Mackall <mpm@selenic.com>
> > Cc: Christoph Lameter <cl@linux.com>
> > Signed-off-by: Nick Piggin <npiggin@suse.de>
> 
> I have applied the patch series. I see you have cc'd stable so I assume
> you want this in 2.6.30, right? This seems like a rather serious bug but

Thanks. I think it makes sense to into 2.6.30. Also probably all active
.stable kernels.


> I wonder why we've gotten away with it for so long? Is there a test
> program or a known workload that breaks without this?

Well... it isn't doing what reclaim code wants, and it is differing
behaviour between SLAB and SL?B, so I think it is fairly safe to
merge these now.

It doesn't look like too much *significant* changes to heuristics, but
things will get skewed here and there.

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