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

[Matt Mackall <mpm@selenic.com>]

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
> 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?

Appears to me to be less a correctness than a balancing issue. reclaim
state is a back channel into the shrink code that says 'yes, this is
working'. Without it, things should still work, but possibly not as
smoothly.

-- 
Mathematics is the supreme nostalgia of our time.

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