From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qc0-f171.google.com (mail-qc0-f171.google.com [209.85.216.171]) by kanga.kvack.org (Postfix) with ESMTP id E9A4C6B0031 for ; Tue, 1 Jul 2014 10:58:57 -0400 (EDT) Received: by mail-qc0-f171.google.com with SMTP id w7so8732228qcr.30 for ; Tue, 01 Jul 2014 07:58:57 -0700 (PDT) Received: from qmta15.emeryville.ca.mail.comcast.net (qmta15.emeryville.ca.mail.comcast.net. [2001:558:fe2d:44:76:96:27:228]) by mx.google.com with ESMTP id 79si29866191qgc.45.2014.07.01.07.58.56 for ; Tue, 01 Jul 2014 07:58:56 -0700 (PDT) Date: Tue, 1 Jul 2014 09:58:52 -0500 (CDT) From: Christoph Lameter 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: owner-linux-mm@kvack.org List-ID: To: David Rientjes Cc: Sasha Levin , Wei Yang , Pekka Enberg , Matt Mackall , Andrew Morton , "linux-mm@kvack.org" , LKML , Dave Jones 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org