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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 75D4FC433C1 for ; Mon, 29 Mar 2021 11:59:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3DC906192C for ; Mon, 29 Mar 2021 11:59:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231258AbhC2L7L (ORCPT ); Mon, 29 Mar 2021 07:59:11 -0400 Received: from mx2.suse.de ([195.135.220.15]:41512 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231614AbhC2L7J (ORCPT ); Mon, 29 Mar 2021 07:59:09 -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 892A9B3C9; Mon, 29 Mar 2021 11:59:08 +0000 (UTC) To: Sergei Trofimovich , Andrew Morton , David Hildenbrand , Andrey Konovalov Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20210327180348.137d8fe2@sf> <20210327182144.3213887-1-slyfox@gentoo.org> From: Vlastimil Babka Subject: Re: [PATCH v2] mm: page_alloc: ignore init_on_free=1 for debug_pagealloc=1 Message-ID: Date: Mon, 29 Mar 2021 13:59:07 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <20210327182144.3213887-1-slyfox@gentoo.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/27/21 7:21 PM, Sergei Trofimovich wrote: > On !ARCH_SUPPORTS_DEBUG_PAGEALLOC (like ia64) debug_pagealloc=1 > implies page_poison=on: > > if (page_poisoning_enabled() || > (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) && > debug_pagealloc_enabled())) > static_branch_enable(&_page_poisoning_enabled); > > page_poison=on needs to init_on_free=1. > > Before the change id happened too late for the following case: > - have PAGE_POISONING=y > - have page_poison unset > - have !ARCH_SUPPORTS_DEBUG_PAGEALLOC arch (like ia64) > - have init_on_free=1 > - have debug_pagealloc=1 > > That way we get both keys enabled: > - static_branch_enable(&init_on_free); > - static_branch_enable(&_page_poisoning_enabled); > > which leads to poisoned pages returned for __GFP_ZERO pages. Good catch, thanks for finding the root cause! > After the change we execute only: > - static_branch_enable(&_page_poisoning_enabled); > and ignore init_on_free=1. > CC: Vlastimil Babka > CC: Andrew Morton > CC: linux-mm@kvack.org > CC: David Hildenbrand > CC: Andrey Konovalov > Link: https://lkml.org/lkml/2021/3/26/443 > Signed-off-by: Sergei Trofimovich Acked-by: Vlastimil Babka 8db26a3d4735 ("mm, page_poison: use static key more efficiently") Cc: > --- > mm/page_alloc.c | 30 +++++++++++++++++------------- > 1 file changed, 17 insertions(+), 13 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index d57d9b4f7089..10a8a1d28c11 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -764,32 +764,36 @@ static inline void clear_page_guard(struct zone *zone, struct page *page, > */ > void init_mem_debugging_and_hardening(void) > { > + bool page_poison_requested = page_poisoning_enabled(); > + > +#ifdef CONFIG_PAGE_POISONING > + /* > + * Page poisoning is debug page alloc for some arches. If > + * either of those options are enabled, enable poisoning. > + */ > + if (page_poisoning_enabled() || > + (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) && > + debug_pagealloc_enabled())) { > + static_branch_enable(&_page_poisoning_enabled); > + page_poison_requested = true; > + } > +#endif > + > if (_init_on_alloc_enabled_early) { > - if (page_poisoning_enabled()) > + if (page_poison_requested) > pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, " > "will take precedence over init_on_alloc\n"); > else > static_branch_enable(&init_on_alloc); > } > if (_init_on_free_enabled_early) { > - if (page_poisoning_enabled()) > + if (page_poison_requested) > pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, " > "will take precedence over init_on_free\n"); > else > static_branch_enable(&init_on_free); > } > > -#ifdef CONFIG_PAGE_POISONING > - /* > - * Page poisoning is debug page alloc for some arches. If > - * either of those options are enabled, enable poisoning. > - */ > - if (page_poisoning_enabled() || > - (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) && > - debug_pagealloc_enabled())) > - static_branch_enable(&_page_poisoning_enabled); > -#endif > - > #ifdef CONFIG_DEBUG_PAGEALLOC > if (!debug_pagealloc_enabled()) > return; >