Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932166AbaGAO67 (ORCPT ); Tue, 1 Jul 2014 10:58:59 -0400 Received: from qmta01.emeryville.ca.mail.comcast.net ([76.96.30.16]:57098 "EHLO qmta01.emeryville.ca.mail.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757662AbaGAO64 (ORCPT ); Tue, 1 Jul 2014 10:58:56 -0400 Date: Tue, 1 Jul 2014 09:58:52 -0500 (CDT) From: Christoph Lameter To: David Rientjes cc: Sasha Levin , Wei Yang , Pekka Enberg , Matt Mackall , Andrew Morton , "linux-mm@kvack.org" , LKML , Dave Jones Subject: Re: mm: slub: invalid memory access in setup_object In-Reply-To: Message-ID: References: <53AAFDF7.2010607@oracle.com> Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 30 Jun 2014, David Rientjes wrote: > It's not at all clear to me that that patch is correct. Wei? Looks ok to me. But I do not like the convoluted code in new_slab() which Wei's patch does not make easier to read. Makes it difficult for the reader to see whats going on. Lets drop the use of the variable named "last". Subject: slub: Only call setup_object once for each object Modify the logic for object initialization to be less convoluted and initialize an object only once. Signed-off-by: Christoph Lameter Index: linux/mm/slub.c =================================================================== --- linux.orig/mm/slub.c 2014-07-01 09:50:02.486846653 -0500 +++ linux/mm/slub.c 2014-07-01 09:52:07.918802585 -0500 @@ -1409,7 +1409,6 @@ static struct page *new_slab(struct kmem { struct page *page; void *start; - void *last; void *p; int order; @@ -1432,15 +1431,11 @@ static struct page *new_slab(struct kmem if (unlikely(s->flags & SLAB_POISON)) memset(start, POISON_INUSE, PAGE_SIZE << order); - last = start; for_each_object(p, s, start, page->objects) { - setup_object(s, page, last); - set_freepointer(s, last, p); - last = p; + setup_object(s, page, p); + set_freepointer(s, p, p + s->size); } - setup_object(s, page, last); - set_freepointer(s, last, NULL); - + set_freepointer(s, start + (page->objects - 1) * s->size, NULL); page->freelist = start; page->inuse = page->objects; page->frozen = 1; -- 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/