From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757745Ab3BYRST (ORCPT ); Mon, 25 Feb 2013 12:18:19 -0500 Received: from mx4-phx2.redhat.com ([209.132.183.25]:33843 "EHLO mx4-phx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754365Ab3BYRSS (ORCPT ); Mon, 25 Feb 2013 12:18:18 -0500 Date: Mon, 25 Feb 2013 12:18:10 -0500 (EST) From: Aaron Tomlin To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Rik , glommer@parallels.com Message-ID: <591256534.8212978.1361812690861.JavaMail.root@redhat.com> In-Reply-To: <813482873.8209105.1361812140956.JavaMail.root@redhat.com> Subject: Re: [PATCH v2] mm: slab: Verify the nodeid passed to ____cache_alloc_node MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [10.33.1.237] X-Mailer: Zimbra 7.2.0_GA_2669 (ZimbraWebClient - GC24 (Linux)/7.2.0_GA_2669) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, This patch is in response to bz#42967 [1]. Using VM_BUG_ON instead of a generic BUG_ON so it's used only when CONFIG_DEBUG_VM is set, given that ____cache_alloc_node() is a hot code path. Cheers, Aaron [1]: https://bugzilla.kernel.org/show_bug.cgi?id=42967 ---8<--- mm: slab: Verify the nodeid passed to ____cache_alloc_node If the nodeid is > num_online_nodes() this can cause an Oops and a panic(). The purpose of this patch is to assert if this condition is true to aid debugging efforts rather than some random NULL pointer dereference or page fault. Signed-off-by: Aaron Tomlin slab.c | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/slab.c b/mm/slab.c index e7667a3..735e8bd 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -3412,6 +3412,7 @@ static void *____cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, void *obj; int x; + VM_BUG_ON(nodeid > num_online_nodes()); l3 = cachep->nodelists[nodeid]; BUG_ON(!l3);