From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754825AbYGWWNv (ORCPT ); Wed, 23 Jul 2008 18:13:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753605AbYGWWNm (ORCPT ); Wed, 23 Jul 2008 18:13:42 -0400 Received: from relay1.sgi.com ([192.48.171.29]:45713 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753587AbYGWWNl (ORCPT ); Wed, 23 Jul 2008 18:13:41 -0400 Date: Wed, 23 Jul 2008 17:13:38 -0500 From: Russ Anderson To: Nick Piggin Cc: mingo@elte.hu, tglx@linutronix.de, Tony Luck , linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org Subject: Re: [PATCH 1/2] mm: Avoid putting a bad page back on the LRU v7 Message-ID: <20080723221338.GB193408@sgi.com> Reply-To: Russ Anderson References: <20080718203606.GE29621@sgi.com> <200807221242.10552.nickpiggin@yahoo.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200807221242.10552.nickpiggin@yahoo.com.au> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 22, 2008 at 12:42:10PM +1000, Nick Piggin wrote: > On Saturday 19 July 2008 06:36, Russ Anderson wrote: > > [PATCH 1/2] mm: Avoid putting a bad page back on the LRU v7 > > > > Prevent a page with a physical memory error from being placed back > > on the LRU. A new page flag (PG_memerror) is added if > > CONFIG_PAGEFLAGS_EXTENDED is defined. > > > > Signed-off-by: Russ Anderson > > Reviewed-by: Christoph Lameter > > > > --- > > include/linux/page-flags.h | 18 ++++++++++++++++-- > > mm/migrate.c | 31 ++++++++++++++++++++++++++++++- > > mm/page_alloc.c | 13 ++++++++----- > > 3 files changed, 54 insertions(+), 8 deletions(-) > > > > Index: linux/mm/page_alloc.c > > =================================================================== > > --- linux.orig/mm/page_alloc.c 2008-07-18 15:15:48.000000000 -0500 > > +++ linux/mm/page_alloc.c 2008-07-18 15:16:09.000000000 -0500 > > @@ -602,10 +602,10 @@ static int prep_new_page(struct page *pa > > bad_page(page); > > > > /* > > - * For now, we report if PG_reserved was found set, but do not > > - * clear it, and do not allocate the page: as a safety net. > > + * For now, we report if PG_reserved or PG_memerror was found set, but > > + * do not clear it, and do not allocate the page: as a safety net. > > */ > > - if (PageReserved(page)) > > + if (PageReserved(page) || PageMemError(page)) > > return 1; > > > > page->flags &= ~(1 << PG_uptodate | 1 << PG_error | 1 << PG_reclaim | > > @@ -2475,8 +2475,11 @@ static void setup_zone_migrate_reserve(s > > continue; > > page = pfn_to_page(pfn); > > > > - /* Blocks with reserved pages will never free, skip them. */ > > - if (PageReserved(page)) > > + /* > > + * Blocks with reserved pages or memory errors will never > > + * free, skip them. > > + */ > > + if (PageReserved(page) || PageMemError(page)) > > continue; > > > > block_migratetype = get_pageblock_migratetype(page); > > I don't like adding more branches like this into fastpaths like this. It > would make a lot more sense to me if you just had some private module that > does the job of isolating the page from the lru and/or elevating their > refcount so that they do not get put back on freelists. That is how it works. If PageMemError is set the migration code leaves the page with an elevated refcount. The PageMemError() check was to avoid reallocating the page was an additional safty net. I'll pull the checks. > Migration may need something to perhaps allow migrations of pages not on > LRU lists but have PageMemError set which is OK, but I really don't like > adding code and branches to page_alloc.c if possible.... > > Thanks, > Nick -- Russ Anderson, OS RAS/Partitioning Project Lead SGI - Silicon Graphics Inc rja@sgi.com