From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.4 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A9779C388F9 for ; Tue, 27 Oct 2020 17:42:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 608A821556 for ; Tue, 27 Oct 2020 17:42:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1803023AbgJ0RmM (ORCPT ); Tue, 27 Oct 2020 13:42:12 -0400 Received: from mx2.suse.de ([195.135.220.15]:35804 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1821208AbgJ0RlS (ORCPT ); Tue, 27 Oct 2020 13:41:18 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id CB7E4AAF1; Tue, 27 Oct 2020 17:41:16 +0000 (UTC) Subject: Re: [PATCH 3/3] mm, page_alloc: reduce static keys in prep_new_page() From: Vlastimil Babka To: David Hildenbrand , Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Alexander Potapenko , Kees Cook , Michal Hocko , Mateusz Nosek , Laura Abbott References: <20201026173358.14704-1-vbabka@suse.cz> <20201026173358.14704-4-vbabka@suse.cz> <93ab79df-cf8c-294b-3ed1-8a563e4a452b@redhat.com> <1fc7ec3a-367c-eb9f-1cb4-b9e015fea87c@suse.cz> <81faf3d6-9536-ff00-447d-e964a010492d@suse.cz> Message-ID: <38de5bb0-5559-d069-0ce0-daec66ef2746@suse.cz> Date: Tue, 27 Oct 2020 18:41:16 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.3.3 MIME-Version: 1.0 In-Reply-To: <81faf3d6-9536-ff00-447d-e964a010492d@suse.cz> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/27/20 2:32 PM, Vlastimil Babka wrote: > So my conclusion: > - We can remove PAGE_POISONING_NO_SANITY because it only makes sense with > PAGE_POISONING_ZERO, and we can use init_on_free instead Note for this we first have to make sanity checking compatible with hibernation, but that should be easy as the zeroing variants already paved the way. The patch below will be added to the next version of the series: From 44474ee27c4f5248061ea2e5bbc2aeefc91bcdfc Mon Sep 17 00:00:00 2001 From: Vlastimil Babka Date: Tue, 27 Oct 2020 18:25:17 +0100 Subject: [PATCH] kernel/power: allow hibernation with page_poison sanity checking Page poisoning used to be incompatible with hibernation, as the state of poisoned pages was lost after resume, thus enabling CONFIG_HIBERNATION forces CONFIG_PAGE_POISONING_NO_SANITY. For the same reason, the poisoning with zeroes variant CONFIG_PAGE_POISONING_ZERO used to disable hibernation. The latter restriction was removed by commit 1ad1410f632d ("PM / Hibernate: allow hibernation with PAGE_POISONING_ZERO") and similarly for init_on_free by commit 18451f9f9e58 ("PM: hibernate: fix crashes with init_on_free=1") by making sure free pages are cleared after resume. We can use the same mechanism to instead poison free pages with PAGE_POISON after resume. This covers both zero and 0xAA patterns. Thus we can remove the Kconfig restriction that disables page poison sanity checking when hibernation is enabled. Signed-off-by: Vlastimil Babka --- kernel/power/hibernate.c | 2 +- kernel/power/power.h | 2 +- kernel/power/snapshot.c | 14 ++++++++++---- mm/Kconfig.debug | 1 - 4 files changed, 12 insertions(+), 7 deletions(-) diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c index 2fc7d509a34f..da0b41914177 100644 --- a/kernel/power/hibernate.c +++ b/kernel/power/hibernate.c @@ -326,7 +326,7 @@ static int create_image(int platform_mode) if (!in_suspend) { events_check_enabled = false; - clear_free_pages(); + clear_or_poison_free_pages(); } platform_leave(platform_mode); diff --git a/kernel/power/power.h b/kernel/power/power.h index 24f12d534515..778bf431ec02 100644 --- a/kernel/power/power.h +++ b/kernel/power/power.h @@ -106,7 +106,7 @@ extern int create_basic_memory_bitmaps(void); extern void free_basic_memory_bitmaps(void); extern int hibernate_preallocate_memory(void); -extern void clear_free_pages(void); +extern void clear_or_poison_free_pages(void); /** * Auxiliary structure used for reading the snapshot image data and diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c index 46b1804c1ddf..6b1c84afa891 100644 --- a/kernel/power/snapshot.c +++ b/kernel/power/snapshot.c @@ -1144,7 +1144,7 @@ void free_basic_memory_bitmaps(void) pr_debug("Basic memory bitmaps freed\n"); } -void clear_free_pages(void) +void clear_or_poison_free_pages(void) { struct memory_bitmap *bm = free_pages_map; unsigned long pfn; @@ -1152,12 +1152,18 @@ void clear_free_pages(void) if (WARN_ON(!(free_pages_map))) return; - if (IS_ENABLED(CONFIG_PAGE_POISONING_ZERO) || want_init_on_free()) { + if (page_poisoning_enabled() || want_init_on_free()) { 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)); + if (pfn_valid(pfn)) { + struct page *page = pfn_to_page(pfn); + if (page_poisoning_enabled_static()) + kernel_poison_pages(page, 1); + else if (want_init_on_free()) + clear_highpage(page); + + } pfn = memory_bm_next_pfn(bm); } diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug index 864f129f1937..c57786ad5be9 100644 --- a/mm/Kconfig.debug +++ b/mm/Kconfig.debug @@ -64,7 +64,6 @@ config PAGE_OWNER config PAGE_POISONING bool "Poison pages after freeing" - select PAGE_POISONING_NO_SANITY if HIBERNATION help Fill the pages with poison patterns after free_pages() and verify the patterns before alloc_pages. The filling of the memory helps -- 2.29.0