linux-kernel - Re: [PATCH] slab/mempolicy: always use local policy from interrupt context v3

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Date:	Thu, 31 May 2012 09:13:51 -0500 (CDT)
From:	Christoph Lameter <cl@...ux.com>
To:	Andi Kleen <andi@...stfloor.org>
cc:	linux-kernel@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>,
	penberg@...nel.org
Subject: Re: [PATCH] slab/mempolicy: always use local policy from interrupt
 context v3

>
> slab_node() could access current->mempolicy from interrupt context.
> However there's a race condition during exit where the mempolicy
> is first freed and then the pointer zeroed.
>
> Using this from interrupts seems bogus anyways. The interrupt
> will interrupt a random process and therefore get a random
> mempolicy. Many times, this will be idle's, which noone can change.
>
> Just disable this here and always use local for slab
> from interrupts. I also cleaned up the callers of slab_node a bit
> which always passed the same argument.
>
> I believe the original mempolicy code did that in fact,
> so it's likely a regression.

Reviewed-by: Christoph Lameter <cl@...ux.com>

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