Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030221AbbENOU4 (ORCPT ); Thu, 14 May 2015 10:20:56 -0400 Received: from mail-wg0-f51.google.com ([74.125.82.51]:36084 "EHLO mail-wg0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933835AbbENOUA (ORCPT ); Thu, 14 May 2015 10:20:00 -0400 From: Anisse Astier Cc: Anisse Astier , Andrew Morton , Mel Gorman , "Kirill A. Shutemov" , David Rientjes , Alan Cox , Linus Torvalds , Peter Zijlstra , PaX Team , Brad Spengler , Kees Cook , Andi Kleen , "Rafael J. Wysocki" , Pavel Machek , Len Brown , linux-mm@kvack.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 3/3] mm: Add debug code for SANITIZE_FREED_PAGES Date: Thu, 14 May 2015 16:19:48 +0200 Message-Id: <1431613188-4511-4-git-send-email-anisse@astier.eu> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1431613188-4511-1-git-send-email-anisse@astier.eu> References: <1431613188-4511-1-git-send-email-anisse@astier.eu> To: unlisted-recipients:; (no To-header on input) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2694 Lines: 86 Add debug code for sanitize freed pages to print status and verify pages at alloc to make sure they're clean. It can be useful if you have crashes when using SANITIZE_FREED_PAGES. Signed-off-by: Anisse Astier --- kernel/power/snapshot.c | 8 ++++++-- mm/Kconfig | 10 ++++++++++ mm/page_alloc.c | 18 ++++++++++++++++++ 3 files changed, 34 insertions(+), 2 deletions(-) diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c index 2335130..e10e736 100644 --- a/kernel/power/snapshot.c +++ b/kernel/power/snapshot.c @@ -1044,9 +1044,13 @@ void clear_free_pages(void) memory_bm_position_reset(bm); pfn = memory_bm_next_pfn(bm); while (pfn != BM_END_OF_MAP) { - if (pfn_valid(pfn)) + if (pfn_valid(pfn)) { +#ifdef CONFIG_SANITIZE_FREED_PAGES_DEBUG + printk(KERN_INFO "Clearing page %p\n", + page_address(pfn_to_page(pfn))); +#endif clear_highpage(pfn_to_page(pfn)); - + } pfn = memory_bm_next_pfn(bm); } memory_bm_position_reset(bm); diff --git a/mm/Kconfig b/mm/Kconfig index e9fb3bd..95364f2 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -647,3 +647,13 @@ config SANITIZE_FREED_PAGES Depending on your workload it will greatly reduce performance. If unsure, say N. + +config SANITIZE_FREED_PAGES_DEBUG + bool "Debug sanitize pages feature" + default n + depends on SANITIZE_FREED_PAGES && DEBUG_KERNEL + help + This option adds some debugging code for the SANITIZE_FREED_PAGES + option, as well as verification code to ensure pages are really + zeroed. Don't enable unless you want to debug this feature. + If unsure, say N. diff --git a/mm/page_alloc.c b/mm/page_alloc.c index c29e3a0..d76325ad 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -975,6 +975,24 @@ static int prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags, for (i = 0; i < (1 << order); i++) clear_highpage(page + i); #endif +#ifdef CONFIG_SANITIZE_FREED_PAGES_DEBUG + for (i = 0; i < (1 << order); i++) { + struct page *p = page + i; + void *kaddr = kmap_atomic(p); + void *found = memchr_inv(kaddr, 0, PAGE_SIZE); + + kunmap_atomic(kaddr); + + if (found) { + pr_err("page %p is not zero on alloc! %s\n", + page_address(p), (gfp_flags & + __GFP_ZERO) ? + "fixing." : ""); + if (gfp_flags & __GFP_ZERO) + clear_highpage(p); + } + } +#endif if (order && (gfp_flags & __GFP_COMP)) prep_compound_page(page, order); -- 1.9.3 -- 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/