From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: slub: use irqsafe_cpu_cmpxchg for put_cpu_partial
Date: Wed, 23 Nov 2011 17:04:51 +0100
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Cc: Pekka Enberg <penberg@kernel.org>, Christian Kujau
 <lists@nerdbynature.de>,  Benjamin Herrenschmidt
 <benh@kernel.crashing.org>, Markus Trippelsdorf <markus@trippelsdorf.de>,
 "Alex,Shi" <alex.shi@intel.com>,  "linux-kernel@vger.kernel.org"
 <linux-kernel@vger.kernel.org>, "linux-mm@kvack.org" <linux-mm@kvack.org>,
 Matt Mackall <mpm@selenic.com>, "netdev@vger.kernel.org"
 <netdev@vger.kernel.org>, Tejun Heo <tj@kernel.org>,  David Rientjes
 <rientjes@google.com>
To: Christoph Lameter <cl@linux.com>
Return-path: <owner-linux-mm@kvack.org>
In-Reply-To: <alpine.DEB.2.00.1111230907330.16139@router.home>
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List-Id: netdev.vger.kernel.org

Le mercredi 23 novembre 2011 =C3=A0 09:14 -0600, Christoph Lameter a =C3=A9=
crit :

> I think he only tested the patch that he showed us. Here is the patch
> cleaned up. Do you Want me to feed you the debug fixes patch by patch a=
s
> well?
>=20
> Subject: slub: use irqsafe_cpu_cmpxchg for put_cpu_partial
>=20
> The cmpxchg must be irq safe. The fallback for this_cpu_cmpxchg only
> disables preemption which results in per cpu partial page operation
> potentially failing on non x86 platforms.
>=20
> Signed-off-by: Christoph Lameter <cl@linux.com>
>=20
> ---
>  mm/slub.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>=20
> Index: linux-2.6/mm/slub.c
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> --- linux-2.6.orig/mm/slub.c	2011-11-23 09:10:48.000000000 -0600
> +++ linux-2.6/mm/slub.c	2011-11-23 09:10:57.000000000 -0600
> @@ -1969,7 +1969,7 @@ int put_cpu_partial(struct kmem_cache *s
>  		page->pobjects =3D pobjects;
>  		page->next =3D oldpage;
>=20
> -	} while (this_cpu_cmpxchg(s->cpu_slab->partial, oldpage, page) !=3D o=
ldpage);
> +	} while (irqsafe_cpu_cmpxchg(s->cpu_slab->partial, oldpage, page) !=3D=
 oldpage);
>  	stat(s, CPU_PARTIAL_FREE);
>  	return pobjects;
>  }

Acked-by: Eric Dumazet <eric.dumazet@gmail.com>

Thanks !


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