Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760962AbZDGPVY (ORCPT ); Tue, 7 Apr 2009 11:21:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759138AbZDGPKI (ORCPT ); Tue, 7 Apr 2009 11:10:08 -0400 Received: from one.firstfloor.org ([213.235.205.2]:41293 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756960AbZDGPKG (ORCPT ); Tue, 7 Apr 2009 11:10:06 -0400 From: Andi Kleen References: <20090407509.382219156@firstfloor.org> In-Reply-To: <20090407509.382219156@firstfloor.org> To: linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org Subject: [PATCH] [5/16] POISON: Add support for poison swap entries Message-Id: <20090407151002.0AA8F1D046E@basil.firstfloor.org> Date: Tue, 7 Apr 2009 17:10:01 +0200 (CEST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4003 Lines: 136 CPU migration uses special swap entry types to trigger special actions on page faults. Extend this mechanism to also support poisoned swap entries, to trigger poison handling on page faults. This allows followon patches to prevent processes from faulting in poisoned pages again. Signed-off-by: Andi Kleen --- include/linux/swap.h | 34 ++++++++++++++++++++++++++++------ include/linux/swapops.h | 38 ++++++++++++++++++++++++++++++++++++++ mm/swapfile.c | 4 ++-- 3 files changed, 68 insertions(+), 8 deletions(-) Index: linux/include/linux/swap.h =================================================================== --- linux.orig/include/linux/swap.h 2009-04-07 16:39:25.000000000 +0200 +++ linux/include/linux/swap.h 2009-04-07 16:39:39.000000000 +0200 @@ -34,16 +34,38 @@ * the type/offset into the pte as 5/27 as well. */ #define MAX_SWAPFILES_SHIFT 5 -#ifndef CONFIG_MIGRATION -#define MAX_SWAPFILES (1 << MAX_SWAPFILES_SHIFT) + +/* + * Use some of the swap files numbers for other purposes. This + * is a convenient way to hook into the VM to trigger special + * actions on faults. + */ + +/* + * NUMA node memory migration support + */ +#ifdef CONFIG_MIGRATION +#define SWP_MIGRATION_NUM 2 +#define SWP_MIGRATION_READ (MAX_SWAPFILES + SWP_POISON_NUM + 1) +#define SWP_MIGRATION_WRITE (MAX_SWAPFILES + SWP_POISON_NUM + 2) #else -/* Use last two entries for page migration swap entries */ -#define MAX_SWAPFILES ((1 << MAX_SWAPFILES_SHIFT)-2) -#define SWP_MIGRATION_READ MAX_SWAPFILES -#define SWP_MIGRATION_WRITE (MAX_SWAPFILES + 1) +#define SWP_MIGRATION_NUM 0 #endif /* + * Handling of poisoned pages with memory corruption. + */ +#ifdef CONFIG_MEMORY_FAILURE +#define SWP_POISON_NUM 1 +#define SWP_POISON (MAX_SWAPFILES + 1) +#else +#define SWP_POISON_NUM 0 +#endif + +#define MAX_SWAPFILES \ + ((1 << MAX_SWAPFILES_SHIFT) - SWP_MIGRATION_NUM - SWP_POISON_NUM) + +/* * Magic header for a swap area. The first part of the union is * what the swap magic looks like for the old (limited to 128MB) * swap area format, the second part of the union adds - in the Index: linux/include/linux/swapops.h =================================================================== --- linux.orig/include/linux/swapops.h 2009-04-07 16:39:25.000000000 +0200 +++ linux/include/linux/swapops.h 2009-04-07 16:39:39.000000000 +0200 @@ -131,3 +131,41 @@ #endif +#ifdef CONFIG_MEMORY_FAILURE +/* + * Support for poisoned pages + */ +static inline swp_entry_t make_poison_entry(struct page *page) +{ + BUG_ON(!PageLocked(page)); + return swp_entry(SWP_POISON, page_to_pfn(page)); +} + +static inline int is_poison_entry(swp_entry_t entry) +{ + return swp_type(entry) == SWP_POISON; +} +#else + +static inline swp_entry_t make_poison_entry(struct page *page) +{ + return swp_entry(0, 0); +} + +static inline int is_poison_entry(swp_entry_t swp) +{ + return 0; +} +#endif + +#if defined(CONFIG_MEMORY_FAILURE) || defined(CONFIG_MIGRATION) +static inline int non_swap_entry(swp_entry_t entry) +{ + return swp_type(entry) > MAX_SWAPFILES; +} +#else +static inline int non_swap_entry(swp_entry_t entry) +{ + return 0; +} +#endif Index: linux/mm/swapfile.c =================================================================== --- linux.orig/mm/swapfile.c 2009-04-07 16:39:25.000000000 +0200 +++ linux/mm/swapfile.c 2009-04-07 16:39:39.000000000 +0200 @@ -579,7 +579,7 @@ struct swap_info_struct *p; struct page *page = NULL; - if (is_migration_entry(entry)) + if (non_swap_entry(entry)) return 1; p = swap_info_get(entry); @@ -1949,7 +1949,7 @@ unsigned long offset, type; int result = 0; - if (is_migration_entry(entry)) + if (non_swap_entry(entry)) return 1; type = swp_type(entry); -- 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/