From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f181.google.com (mail-wi0-f181.google.com [209.85.212.181]) by kanga.kvack.org (Postfix) with ESMTP id D3D4A6B006E for ; Thu, 7 May 2015 02:36:40 -0400 (EDT) Received: by wizk4 with SMTP id k4so229449129wiz.1 for ; Wed, 06 May 2015 23:36:40 -0700 (PDT) Received: from mail-wi0-f169.google.com (mail-wi0-f169.google.com. [209.85.212.169]) by mx.google.com with ESMTPS id jt5si1743147wjc.48.2015.05.06.23.36.37 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 06 May 2015 23:36:38 -0700 (PDT) Received: by wizk4 with SMTP id k4so229447868wiz.1 for ; Wed, 06 May 2015 23:36:37 -0700 (PDT) From: Anisse Astier Subject: [PATCH v3 4/4] mm: Add debug code for SANITIZE_FREED_PAGES Date: Thu, 7 May 2015 08:34:12 +0200 Message-Id: <1430980452-2767-5-git-send-email-anisse@astier.eu> In-Reply-To: <1430980452-2767-1-git-send-email-anisse@astier.eu> References: <1430980452-2767-1-git-send-email-anisse@astier.eu> Sender: owner-linux-mm@kvack.org List-ID: 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 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 673ade1..dfbfb5f 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..f6105e5 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org