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=-10.8 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 4E989C433E0 for ; Fri, 5 Mar 2021 23:50:00 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C30E3650AA for ; Fri, 5 Mar 2021 23:49:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C30E3650AA 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 560AF6B0006; Fri, 5 Mar 2021 18:49:59 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 524746B006C; Fri, 5 Mar 2021 18:49:59 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3EBE66B006E; Fri, 5 Mar 2021 18:49:59 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0131.hostedemail.com [216.40.44.131]) by kanga.kvack.org (Postfix) with ESMTP id 221A06B0006 for ; Fri, 5 Mar 2021 18:49:59 -0500 (EST) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id E13645DF2 for ; Fri, 5 Mar 2021 23:49:58 +0000 (UTC) X-FDA: 77887466076.18.7DBEBF8 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf16.hostedemail.com (Postfix) with ESMTP id 2161480192D8 for ; Fri, 5 Mar 2021 23:49:57 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id A66BD65073; Fri, 5 Mar 2021 23:49:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1614988197; bh=T1WRciFZ6SROSTvnq6Id8/sVq43F1qvTO0XybjxDSNs=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=2J4OjFKKqN1PUcQG2vhC4e4UvgSYhgzDkv/q78FCoHnZt4B511g2fPskOH7C/cfeo TcYzPlKhPlrZOeiNlCy5ilQYwSnTfvDkR+cfhwC8OULkj7HVL5EAcsjHHfmQnQs2MY ERQVAQ7Uq32B4Ha2x56xXw/JUWk75dvlyr/B1DSs= Date: Fri, 5 Mar 2021 15:49:56 -0800 From: Andrew Morton To: Andrey Konovalov Cc: Alexander Potapenko , Catalin Marinas , Will Deacon , Vincenzo Frascino , Dmitry Vyukov , Andrey Ryabinin , Marco Elver , Peter Collingbourne , Evgenii Stepanov , Branislav Rankov , Kevin Brodsky , kasan-dev@googlegroups.com, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v2] kasan, mm: fix crash with HW_TAGS and DEBUG_PAGEALLOC Message-Id: <20210305154956.3bbfcedab3f549b708d5e2fa@linux-foundation.org> In-Reply-To: <24cd7db274090f0e5bc3adcdc7399243668e3171.1614987311.git.andreyknvl@google.com> References: <24cd7db274090f0e5bc3adcdc7399243668e3171.1614987311.git.andreyknvl@google.com> 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-Stat-Signature: o83w7q1b4kewfwbpkpifp34gy6dgiwfx X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 2161480192D8 Received-SPF: none (linux-foundation.org>: No applicable sender policy available) receiver=imf16; identity=mailfrom; envelope-from=""; helo=mail.kernel.org; client-ip=198.145.29.99 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1614988197-1416 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 Sat, 6 Mar 2021 00:36:33 +0100 Andrey Konovalov wrote: > Currently, kasan_free_nondeferred_pages()->kasan_free_pages() is called > after debug_pagealloc_unmap_pages(). This causes a crash when > debug_pagealloc is enabled, as HW_TAGS KASAN can't set tags on an > unmapped page. > > This patch puts kasan_free_nondeferred_pages() before > debug_pagealloc_unmap_pages() and arch_free_page(), which can also make > the page unavailable. > > ... > > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1304,6 +1304,12 @@ static __always_inline bool free_pages_prepare(struct page *page, > > kernel_poison_pages(page, 1 << order); > > + /* > + * With hardware tag-based KASAN, memory tags must be set before the > + * page becomes unavailable via debug_pagealloc or arch_free_page. > + */ > + kasan_free_nondeferred_pages(page, order, fpi_flags); > + > /* > * arch_free_page() can make the page's contents inaccessible. s390 > * does this. So nothing which can access the page's contents should > @@ -1313,8 +1319,6 @@ static __always_inline bool free_pages_prepare(struct page *page, > > debug_pagealloc_unmap_pages(page, 1 << order); > > - kasan_free_nondeferred_pages(page, order, fpi_flags); > - > return true; > } kasan_free_nondeferred_pages() has only two args in current mainline. I fixed that in the obvious manner...