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Date: Mon, 15 Jun 2009 10:43:09 -0400 (EDT)
From: Christoph Lameter <cl@linux-foundation.org>
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To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
cc: Pekka J Enberg <penberg@cs.helsinki.fi>, torvalds@linux-foundation.org,
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       kamezawa.hiroyu@jp.fujitsu.com, lizf@cn.fujitsu.com, mingo@elte.hu,
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Subject: Re: [GIT PULL v2] Early SLAB fixes for 2.6.31
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On Sat, 13 Jun 2009, Benjamin Herrenschmidt wrote:

>
> > Adds code to hot code path.
>
> A single mask which should be mostly in the noise...
>
> > The allocators mask flags passed to the page allocator through
> > GFP_RECLAIM_MASK|GFP_CONSTRAINT_MASK. This is done outside of the critical
> > code paths.
> >
> > The might_sleep issues may be fixed by adding another check to
> > __might_sleep().
>
> That is not enough because slab and slub explicitely re-enable
> interrupts when __GFP_WAIT is set, which is the problem we need to solve
> in the first place, so we need to do the masking there.

If you mask the bit then both wont reenable interrupts.