From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f51.google.com (mail-wg0-f51.google.com [74.125.82.51]) by kanga.kvack.org (Postfix) with ESMTP id 8776E6B009E for ; Mon, 18 May 2015 06:23:22 -0400 (EDT) Received: by wgfl8 with SMTP id l8so30440812wgf.2 for ; Mon, 18 May 2015 03:23:21 -0700 (PDT) Received: from mail-wi0-f176.google.com (mail-wi0-f176.google.com. [209.85.212.176]) by mx.google.com with ESMTPS id l9si11925337wia.121.2015.05.18.03.23.21 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 18 May 2015 03:23:21 -0700 (PDT) Received: by wibt6 with SMTP id t6so63927963wib.0 for ; Mon, 18 May 2015 03:23:20 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <7216052.tCNGRiLFYJ@vostro.rjw.lan> References: <1431613188-4511-1-git-send-email-anisse@astier.eu> <1431613188-4511-2-git-send-email-anisse@astier.eu> <7216052.tCNGRiLFYJ@vostro.rjw.lan> From: Anisse Astier Date: Mon, 18 May 2015 12:23:00 +0200 Message-ID: Subject: Re: [PATCH v4 1/3] PM / Hibernate: prepare for SANITIZE_FREED_PAGES Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: "Rafael J. Wysocki" Cc: Andrew Morton , Mel Gorman , "Kirill A. Shutemov" , David Rientjes , Alan Cox , Linus Torvalds , Peter Zijlstra , PaX Team , Brad Spengler , Kees Cook , Andi Kleen , Pavel Machek , Len Brown , linux-mm@kvack.org, Linux PM list , Linux Kernel Mailing List Hi Rafael, Thanks for taking the time to review this. On Sat, May 16, 2015 at 2:28 AM, Rafael J. Wysocki wrote: > On Thursday, May 14, 2015 04:19:46 PM Anisse Astier wrote: >> SANITIZE_FREED_PAGES feature relies on having all pages going through >> the free_pages_prepare path in order to be cleared before being used. In >> the hibernate use case, free pages will automagically appear in the >> system without being cleared, left there by the loading kernel. >> >> This patch will make sure free pages are cleared on resume; when we'll >> enable SANITIZE_FREED_PAGES. We free the pages just after resume because >> we can't do it later: going through any device resume code might >> allocate some memory and invalidate the free pages bitmap. >> >> Signed-off-by: Anisse Astier >> --- >> kernel/power/hibernate.c | 4 +++- >> kernel/power/power.h | 2 ++ >> kernel/power/snapshot.c | 22 ++++++++++++++++++++++ >> 3 files changed, 27 insertions(+), 1 deletion(-) >> >> diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c >> index 2329daa..0a73126 100644 >> --- a/kernel/power/hibernate.c >> +++ b/kernel/power/hibernate.c >> @@ -305,9 +305,11 @@ static int create_image(int platform_mode) >> error); >> /* Restore control flow magically appears here */ >> restore_processor_state(); >> - if (!in_suspend) >> + if (!in_suspend) { >> events_check_enabled = false; >> >> + clear_free_pages(); > > Again, why don't you do that at the swsusp_free() time? Because it's too late, the kernel has already been through device resume code, and the free pages bitmap isn't valid anymore; device resume code might allocate memory, and we'd be clearing those pages as well. >> diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c >> index 5235dd4..2335130 100644 >> --- a/kernel/power/snapshot.c >> +++ b/kernel/power/snapshot.c >> @@ -1032,6 +1032,28 @@ void free_basic_memory_bitmaps(void) >> pr_debug("PM: Basic memory bitmaps freed\n"); >> } >> >> +void clear_free_pages(void) >> +{ >> +#ifdef CONFIG_SANITIZE_FREED_PAGES >> + struct memory_bitmap *bm = free_pages_map; >> + unsigned long pfn; >> + >> + if (WARN_ON(!(free_pages_map))) > > One paren too many. Thanks, will be fixed. > >> + return; >> + >> + memory_bm_position_reset(bm); >> + pfn = memory_bm_next_pfn(bm); >> + while (pfn != BM_END_OF_MAP) { >> + if (pfn_valid(pfn)) >> + clear_highpage(pfn_to_page(pfn)); > > Is clear_highpage() also fine for non-highmem pages? > Yes, it works fine for low memory too because kmap_atomic will just return the page address if it's already mapped. Regards, Anisse -- 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