Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753114Ab1FHT4k (ORCPT ); Wed, 8 Jun 2011 15:56:40 -0400 Received: from e7.ny.us.ibm.com ([32.97.182.137]:49671 "EHLO e7.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751181Ab1FHT4i (ORCPT ); Wed, 8 Jun 2011 15:56:38 -0400 Date: Wed, 8 Jun 2011 12:56:35 -0700 From: "Paul E. McKenney" To: Eric B Munson Cc: arnd@arndb.de, akpm@linux-foundation.org, mingo@elte.hu, randy.dunlap@oracle.com, josh@joshtriplett.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, mgorman@suse.de, linux-mm@kvack.org Subject: Re: [PATCH] Add debugging boundary check to pfn_to_page Message-ID: <20110608195635.GI2324@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <1307560734-3915-1-git-send-email-emunson@mgebm.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1307560734-3915-1-git-send-email-emunson@mgebm.net> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3291 Lines: 94 On Wed, Jun 08, 2011 at 03:18:54PM -0400, Eric B Munson wrote: > Bugzilla 36192 showed a problem where pages were being accessed outside of > a node boundary. It would be helpful in diagnosing this kind of problem to > have pfn_to_page complain when a page is accessed outside of the node boundary. > This patch adds a new debug config option which adds a WARN_ON in pfn_to_page > that will complain when pages are accessed outside of the node boundary. > > Signed-of-by: Eric B Munson > --- > include/asm-generic/memory_model.h | 19 +++++++++++++++---- > lib/Kconfig.debug | 10 ++++++++++ > 2 files changed, 25 insertions(+), 4 deletions(-) > > diff --git a/include/asm-generic/memory_model.h b/include/asm-generic/memory_model.h > index fb2d63f..a0f1d19 100644 > --- a/include/asm-generic/memory_model.h > +++ b/include/asm-generic/memory_model.h > @@ -62,11 +62,22 @@ > (unsigned long)(__pg - __section_mem_map_addr(__nr_to_section(__sec))); \ > }) > > -#define __pfn_to_page(pfn) \ > -({ unsigned long __pfn = (pfn); \ > - struct mem_section *__sec = __pfn_to_section(__pfn); \ > - __section_mem_map_addr(__sec) + __pfn; \ > +#ifdef CONFIG_DEBUG_MEMORY_MODEL > +#define __pfn_to_page(pfn) \ > +({ unsigned long __pfn = (pfn); \ > + struct mem_section *__sec = __pfn_to_section(__pfn); \ > + struct page *__page = __section_mem_map_addr(__sec) + __pfn; \ > + WARN_ON(__page->flags == 0); \ > + __page; \ > }) > +#else > +#define __pfn_to_page(pfn) \ > +({ unsigned long __pfn = (pfn); \ > + struct mem_section *__sec = __pfn_to_section(__pfn); \ > + __section_mem_map_addr(__sec) + __pfn; \ > +}) > +#endif /* CONFIG_DEBUG_MEMORY_MODEL */ > + The following variant would avoid the duplicate code, FWIW. #define __pfn_to_page_nodebug(pfn) \ ({ unsigned long __pfn = (pfn); \ struct mem_section *__sec = __pfn_to_section(__pfn); \ __section_mem_map_addr(__sec) + __pfn; \ }) #ifdef CONFIG_DEBUG_MEMORY_MODEL #define __pfn_to_page(pfn) \ ({ \ struct page *__page = __pfn_to_page_nodebug(pfn); \ WARN_ON(__page->flags == 0); \ __page; \ }) #else #define __pfn_to_page(pfn) __pfn_to_page_nodebug(pfn) #endif /* CONFIG_DEBUG_MEMORY_MODEL */ Thanx, Paul > #endif /* CONFIG_FLATMEM/DISCONTIGMEM/SPARSEMEM */ > > #define page_to_pfn __page_to_pfn > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index dd373c8..d932cbf 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -777,6 +777,16 @@ config DEBUG_MEMORY_INIT > > If unsure, say Y > > +config DEBUG_MEMORY_MODEL > + bool "Debug memory model" if SPARSEMEM || DISCONTIGMEM > + depends on SPARSEMEM || DISCONTIGMEM > + help > + Enable this to check that page accesses are done within node > + boundaries. The check will warn each time a page is requested > + outside node boundaries. > + > + If unsure, say N > + > config DEBUG_LIST > bool "Debug linked list manipulation" > depends on DEBUG_KERNEL > -- > 1.7.4.1 > -- 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/