Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760564AbXFVSkg (ORCPT ); Fri, 22 Jun 2007 14:40:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759446AbXFVSkU (ORCPT ); Fri, 22 Jun 2007 14:40:20 -0400 Received: from extu-mxob-2.symantec.com ([216.10.194.135]:50238 "EHLO extu-mxob-2.symantec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759377AbXFVSkS (ORCPT ); Fri, 22 Jun 2007 14:40:18 -0400 Date: Fri, 22 Jun 2007 19:39:33 +0100 (BST) From: Hugh Dickins X-X-Sender: hugh@blonde.wat.veritas.com To: Christoph Lameter cc: Linus Torvalds , Nicolas Ferre , ARM Linux Mailing List , Linux Kernel list , Marc Pignat , Andrew Victor , Pierre Ossman , Andrew Morton , Russell King Subject: Re: Oops in a driver while using SLUB as a SLAB allocator In-Reply-To: Message-ID: References: <467A4532.40301@rfo.atmel.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Brightmail-Verdict: VlJEQwAAAAIAAAABAAAAAAAAAAEAAAAAAAAACmluYm94AGxpbnV4LWtlcm5lbEB2Z2VyLmtlcm5lbC5vcmcAY2xhbWV0ZXJAc2dpLmNvbQBhbmRyZXdAc2FucGVvcGxlLmNvbQBuaWNvbGFzLmZlcnJlQHJmby5hdG1lbC5jb20AbGludXgtYXJtLWtlcm5lbEBsaXN0cy5hcm0ubGludXgub3JnLnVrAGFrcG1AbGludXgtZm91bmRhdGlvbi5vcmcAdG9ydmFsZHNAbGludXgtZm91bmRhdGlvbi5vcmcAbWFyYy5waWduYXRAaGV2cy5jaABkcnpldXNAZHJ6ZXVzLmN4AHJta0Bhcm0ubGludXgub3JnLnVrAA== X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2065 Lines: 52 On Fri, 22 Jun 2007, Christoph Lameter wrote: > > Add VM_BUG_ON in case someone uses page_mapping on a slab page > > Detect slab objects being passed to the page oriented functions of the VM. > > It is not sufficient to simply return NULL because the functions calling > page_mapping may depend on other items of the page_struct also to be setup > properly. Moreover the slab object may not be properly aligned. The page > orientedfunctions of the VM expect to operate on page aligned, page sized > objects. operations on objects straddling page boundaries may only affect > the objects partially which may lead to surprising results. > > It is better to detect eventually remaining uses and eliminate them. > > Signed-off-by: Christoph Lameter I'm quite happy with this approach for 2.6.23-rc, along with your ARM dma_map patch which (if I understood aright) rmk approved. Except, haven't you misplaced that VM_BUG_ON between an if and its else? And I'd much prefer you to make it an outright BUG_ON, because many testers have those VM_BUG_ONs configured out. Hugh > > --- > include/linux/mm.h | 5 +---- > 1 file changed, 1 insertion(+), 4 deletions(-) > > Index: linux-2.6/include/linux/mm.h > =================================================================== > --- linux-2.6.orig/include/linux/mm.h 2007-06-22 10:33:27.000000000 -0700 > +++ linux-2.6/include/linux/mm.h 2007-06-22 10:34:09.000000000 -0700 > @@ -603,10 +603,7 @@ static inline struct address_space *page > > if (unlikely(PageSwapCache(page))) > mapping = &swapper_space; > -#ifdef CONFIG_SLUB > - else if (unlikely(PageSlab(page))) > - mapping = NULL; > -#endif > + VM_BUG_ON(PageSlab(page)); > else if (unlikely((unsigned long)mapping & PAGE_MAPPING_ANON)) > mapping = NULL; > return mapping; > - 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/