From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nick Piggin Date: Tue, 22 Jul 2008 02:42:10 +0000 Subject: Re: [PATCH 1/2] mm: Avoid putting a bad page back on the LRU v7 Message-Id: <200807221242.10552.nickpiggin@yahoo.com.au> List-Id: References: <20080718203606.GE29621@sgi.com> In-Reply-To: <20080718203606.GE29621@sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Russ Anderson Cc: mingo@elte.hu, tglx@linutronix.de, Tony Luck , linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org 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. 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