Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759367Ab2EPRtz (ORCPT ); Wed, 16 May 2012 13:49:55 -0400 Received: from na3sys009aog126.obsmtp.com ([74.125.149.155]:51898 "HELO na3sys009aog126.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752607Ab2EPRtx convert rfc822-to-8bit (ORCPT ); Wed, 16 May 2012 13:49:53 -0400 MIME-Version: 1.0 In-Reply-To: <1337034597-1826-1-git-send-email-pshelar@nicira.com> References: <1337034597-1826-1-git-send-email-pshelar@nicira.com> Date: Wed, 16 May 2012 10:49:52 -0700 Message-ID: Subject: Re: [PATCH v2] mm: Fix slab->page _count corruption. From: Pravin Shelar To: cl@linux.com, penberg@kernel.org, mpm@selenic.com Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, jesse@nicira.com, abhide@nicira.com, Pravin B Shelar Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1821 Lines: 51 Hi Christoph, Can you comment on this patch. I have changed it according to your comments. Thanks, Pravin. On Mon, May 14, 2012 at 3:29 PM, Pravin B Shelar wrote: > On arches that do not support this_cpu_cmpxchg_double slab_lock is used > to do atomic cmpxchg() on double word which contains page->_count. > page count can be changed from get_page() or put_page() without taking > slab_lock. That corrupts page counter. > > Following patch fixes it by moving page->_count out of cmpxchg_double > data. So that slub does no change it while updating slub meta-data in > struct page. > > Reported-by: Amey Bhide > Signed-off-by: Pravin B Shelar > --- > ?include/linux/mm_types.h | ? ?8 ++++++++ > ?1 file changed, 8 insertions(+) > > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > index dad95bd..5f558dc 100644 > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -57,8 +57,16 @@ struct page { > ? ? ? ? ? ? ? ?}; > > ? ? ? ? ? ? ? ?union { > +#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \ > + ? ?defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE) > ? ? ? ? ? ? ? ? ? ? ? ?/* Used for cmpxchg_double in slub */ > ? ? ? ? ? ? ? ? ? ? ? ?unsigned long counters; > +#else > + ? ? ? ? ? ? ? ? ? ? ? /* Keep _count separate from slub cmpxchg_double data, > + ? ? ? ? ? ? ? ? ? ? ? ?* As rest of double word is protected by slab_lock > + ? ? ? ? ? ? ? ? ? ? ? ?* but _count is not. */ > + ? ? ? ? ? ? ? ? ? ? ? unsigned counters; > +#endif > > ? ? ? ? ? ? ? ? ? ? ? ?struct { > > -- > 1.7.10 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/