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=-11.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS 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 926A4C07E95 for ; Wed, 14 Jul 2021 02:00:54 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0E6436115B for ; Wed, 14 Jul 2021 02:00:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0E6436115B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 2BC086B0088; Tue, 13 Jul 2021 22:00:54 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 26CB46B008C; Tue, 13 Jul 2021 22:00:54 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1356E6B0092; Tue, 13 Jul 2021 22:00:54 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0246.hostedemail.com [216.40.44.246]) by kanga.kvack.org (Postfix) with ESMTP id E525F6B0088 for ; Tue, 13 Jul 2021 22:00:53 -0400 (EDT) Received: from smtpin35.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id E8D672289F for ; Wed, 14 Jul 2021 02:00:52 +0000 (UTC) X-FDA: 78359539944.35.ADBA780 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf17.hostedemail.com (Postfix) with ESMTP id 815E9F0003B6 for ; Wed, 14 Jul 2021 02:00:52 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 863E9611AB; Wed, 14 Jul 2021 02:00:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1626228051; bh=AkOidA3H+o7OOm9lbz6dv5CMrVs5hpCplVZ49A0VwOU=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=VFWoWTFwq47USqbLc/QWVkGSaNuMO669OvDqmpaQo6FVilGhqE4eMtxF0H4tiYRC0 yQpP+APTgO82U1BYrwCx8u5gLQpiGuLAUsRS1s/x6o1fP3BmYM2Xkw02i5yKbfsm+5 JRZ494JRU8Www/Eoa3tUkJYmSO49eo8iL8ouWph0= Date: Tue, 13 Jul 2021 19:00:51 -0700 From: Andrew Morton To: Sergei Trofimovich Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Kees Cook , Alexander Potapenko , Thomas Gleixner , Vlastimil Babka , bowsingbetee@pm.me Subject: Re: [PATCH] mm: page_alloc: fix page_poison=1 / INIT_ON_ALLOC_DEFAULT_ON interaction Message-Id: <20210713190051.5d841c9269cf7cddf1731e5a@linux-foundation.org> In-Reply-To: <20210712215816.1512739-1-slyfox@gentoo.org> References: <20210712005732.4f9bfa78@zn3> <20210712215816.1512739-1-slyfox@gentoo.org> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 815E9F0003B6 X-Stat-Signature: 5pdwfbaxzguiqz9eiz688m8zze6yhg4j Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=VFWoWTFw; spf=pass (imf17.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none X-HE-Tag: 1626228052-835973 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, 12 Jul 2021 22:58:16 +0100 Sergei Trofimovich wrote: > To reproduce the failure we need the following system: > - kernel command: page_poison=1 init_on_free=0 init_on_alloc=0 > - kernel config: > * CONFIG_INIT_ON_ALLOC_DEFAULT_ON=y > * CONFIG_INIT_ON_FREE_DEFAULT_ON=y > * CONFIG_PAGE_POISONING=y > > 0000000085629bdd: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > 0000000022861832: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > 00000000c597f5b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > CPU: 11 PID: 15195 Comm: bash Kdump: loaded Tainted: G U O 5.13.1-gentoo-x86_64 #1 > Hardware name: System manufacturer System Product Name/PRIME Z370-A, BIOS 2801 01/13/2021 > Call Trace: > dump_stack+0x64/0x7c > __kernel_unpoison_pages.cold+0x48/0x84 > post_alloc_hook+0x60/0xa0 > get_page_from_freelist+0xdb8/0x1000 > __alloc_pages+0x163/0x2b0 > __get_free_pages+0xc/0x30 > pgd_alloc+0x2e/0x1a0 > ? dup_mm+0x37/0x4f0 > mm_init+0x185/0x270 > dup_mm+0x6b/0x4f0 > ? __lock_task_sighand+0x35/0x70 > copy_process+0x190d/0x1b10 > kernel_clone+0xba/0x3b0 > __do_sys_clone+0x8f/0xb0 > do_syscall_64+0x68/0x80 > ? do_syscall_64+0x11/0x80 > entry_SYSCALL_64_after_hwframe+0x44/0xae > > Before the 51cba1eb ("init_on_alloc: Optimize static branches") > init_on_alloc never enabled static branch by default. It could > only be enabed explicitly by init_mem_debugging_and_hardening(). > > But after the 51cba1eb static branch could already be enabled > by default. There was no code to ever disable it. That caused > page_poison=1 / init_on_free=1 conflict. > > This change extends init_mem_debugging_and_hardening() to also > disable static branch disabling. > > ... > > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -840,18 +840,22 @@ void init_mem_debugging_and_hardening(void) > } > #endif > > - if (_init_on_alloc_enabled_early) { > - if (page_poisoning_requested) > + if (_init_on_alloc_enabled_early || > + IS_ENABLED(CONFIG_INIT_ON_ALLOC_DEFAULT_ON)) { > + if (page_poisoning_requested) { > pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, " > "will take precedence over init_on_alloc\n"); > - else > + static_branch_disable(&init_on_alloc); > + } else > static_branch_enable(&init_on_alloc); > } > - if (_init_on_free_enabled_early) { > - if (page_poisoning_requested) > + if (_init_on_free_enabled_early || > + IS_ENABLED(CONFIG_INIT_ON_FREE_DEFAULT_ON)) { > + if (page_poisoning_requested) { > pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, " > "will take precedence over init_on_free\n"); > - else > + static_branch_disable(&init_on_free); > + } else > static_branch_enable(&init_on_free); > } > I'm thinking this is sufficiently serious and sufficiently reported to warrant a cc:stable backport. Agree?