Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756607AbYLAAka (ORCPT ); Sun, 30 Nov 2008 19:40:30 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752201AbYLAAkU (ORCPT ); Sun, 30 Nov 2008 19:40:20 -0500 Received: from extu-mxob-2.symantec.com ([216.10.194.135]:49765 "EHLO extu-mxob-2.symantec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751937AbYLAAkT (ORCPT ); Sun, 30 Nov 2008 19:40:19 -0500 Date: Mon, 1 Dec 2008 00:40:26 +0000 (GMT) From: Hugh Dickins X-X-Sender: hugh@blonde.site To: Andrew Morton cc: Russ Anderson , Nick Piggin , Dave Jones , Arjan van de Ven , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 1/8] badpage: simplify page_alloc flag check+clear In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3921 Lines: 105 Simplify the PAGE_FLAGS checking and clearing when freeing and allocating a page: check the same flags as before when freeing, clear ALL the flags (unless PageReserved) when freeing, check ALL flags off when allocating. Signed-off-by: Hugh Dickins --- include/linux/page-flags.h | 25 ++++++++----------------- mm/page_alloc.c | 19 ++++++------------- 2 files changed, 14 insertions(+), 30 deletions(-) --- badpage0/include/linux/page-flags.h 2008-11-26 12:18:59.000000000 +0000 +++ badpage1/include/linux/page-flags.h 2008-11-28 20:40:33.000000000 +0000 @@ -375,31 +375,22 @@ static inline void __ClearPageTail(struc #define __PG_MLOCKED 0 #endif -#define PAGE_FLAGS (1 << PG_lru | 1 << PG_private | 1 << PG_locked | \ - 1 << PG_buddy | 1 << PG_writeback | \ - 1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \ - __PG_UNEVICTABLE | __PG_MLOCKED) - -/* - * Flags checked in bad_page(). Pages on the free list should not have - * these flags set. It they are, there is a problem. - */ -#define PAGE_FLAGS_CLEAR_WHEN_BAD (PAGE_FLAGS | \ - 1 << PG_reclaim | 1 << PG_dirty | 1 << PG_swapbacked) - /* * Flags checked when a page is freed. Pages being freed should not have * these flags set. It they are, there is a problem. */ -#define PAGE_FLAGS_CHECK_AT_FREE (PAGE_FLAGS | 1 << PG_reserved) +#define PAGE_FLAGS_CHECK_AT_FREE \ + (1 << PG_lru | 1 << PG_private | 1 << PG_locked | \ + 1 << PG_buddy | 1 << PG_writeback | 1 << PG_reserved | \ + 1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \ + __PG_UNEVICTABLE | __PG_MLOCKED) /* * Flags checked when a page is prepped for return by the page allocator. - * Pages being prepped should not have these flags set. It they are, there - * is a problem. + * Pages being prepped should not have any flags set. It they are set, + * there has been a kernel bug or struct page corruption. */ -#define PAGE_FLAGS_CHECK_AT_PREP (PAGE_FLAGS | \ - 1 << PG_reserved | 1 << PG_dirty | 1 << PG_swapbacked) +#define PAGE_FLAGS_CHECK_AT_PREP ((1 << NR_PAGEFLAGS) - 1) #endif /* !__GENERATING_BOUNDS_H */ #endif /* PAGE_FLAGS_H */ --- badpage0/mm/page_alloc.c 2008-11-26 12:19:00.000000000 +0000 +++ badpage1/mm/page_alloc.c 2008-11-28 20:40:33.000000000 +0000 @@ -231,7 +231,6 @@ static void bad_page(struct page *page) printk(KERN_EMERG "Trying to fix it up, but a reboot is needed\n" KERN_EMERG "Backtrace:\n"); dump_stack(); - page->flags &= ~PAGE_FLAGS_CLEAR_WHEN_BAD; set_page_count(page, 0); reset_page_mapcount(page); page->mapping = NULL; @@ -468,16 +467,16 @@ static inline int free_pages_check(struc (page_count(page) != 0) | (page->flags & PAGE_FLAGS_CHECK_AT_FREE))) bad_page(page); - if (PageDirty(page)) - __ClearPageDirty(page); - if (PageSwapBacked(page)) - __ClearPageSwapBacked(page); /* * For now, we report if PG_reserved was found set, but do not * clear it, and do not free the page. But we shall soon need * to do more, for when the ZERO_PAGE count wraps negative. */ - return PageReserved(page); + if (PageReserved(page)) + return 1; + if (page->flags & PAGE_FLAGS_CHECK_AT_PREP) + page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; + return 0; } /* @@ -621,13 +620,7 @@ static int prep_new_page(struct page *pa if (PageReserved(page)) return 1; - page->flags &= ~(1 << PG_uptodate | 1 << PG_error | 1 << PG_reclaim | - 1 << PG_referenced | 1 << PG_arch_1 | - 1 << PG_owner_priv_1 | 1 << PG_mappedtodisk -#ifdef CONFIG_UNEVICTABLE_LRU - | 1 << PG_mlocked -#endif - ); + page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; set_page_private(page, 0); set_page_refcounted(page); -- 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/