From patchwork Thu Feb 13 03:45:31 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anshuman Khandual X-Patchwork-Id: 11379745 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D92E41395 for ; Thu, 13 Feb 2020 03:45:51 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id AF06224685 for ; Thu, 13 Feb 2020 03:45:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AF06224685 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 002366B0509; Wed, 12 Feb 2020 22:45:51 -0500 (EST) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id EF42F6B050B; Wed, 12 Feb 2020 22:45:50 -0500 (EST) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DE4D96B050C; Wed, 12 Feb 2020 22:45:50 -0500 (EST) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0122.hostedemail.com [216.40.44.122]) by kanga.kvack.org (Postfix) with ESMTP id C34916B0509 for ; Wed, 12 Feb 2020 22:45:50 -0500 (EST) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 8D8B2248D for ; Thu, 13 Feb 2020 03:45:50 +0000 (UTC) X-FDA: 76483714860.10.rice84_5005e820af914 X-Spam-Summary: 2,0,0,208171d8c593bb72,d41d8cd98f00b204,anshuman.khandual@arm.com,::linux-kernel@vger.kernel.org:linux-arm-kernel@lists.infradead.org:akpm@linux-foundation.org:catalin.marinas@arm.com:will@kernel.org:mark.rutland@arm.com:david@redhat.com:cai@lca.pw:logang@deltatee.com:arunks@codeaurora.org:dan.j.williams@intel.com:mgorman@techsingularity.net:osalvador@suse.de:ard.biesheuvel@arm.com:steve.capper@arm.com:broonie@kernel.org:valentin.schneider@arm.com:robin.murphy@arm.com:steven.price@arm.com:suzuki.poulose@arm.com:ira.weiny@intel.com:anshuman.khandual@arm.com,RULES_HIT:41:355:379:541:800:960:966:968:973:988:989:1260:1261:1345:1359:1431:1437:1534:1541:1711:1730:1747:1777:1792:1963:2194:2196:2199:2200:2393:2553:2559:2562:2693:2892:2898:3138:3139:3140:3141:3142:3352:3865:3866:3867:3868:3870:3871:4250:4321:4385:5007:6261:6742:7903:8634:10004:11026:11473:11658:11914:12043:12048:12296:12297:12438:12555:12895:12986:13069:13153:13161:13228:13229:13255:13311:13357:14096:1 4181:143 X-HE-Tag: rice84_5005e820af914 X-Filterd-Recvd-Size: 3225 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf44.hostedemail.com (Postfix) with ESMTP for ; Thu, 13 Feb 2020 03:45:49 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E52C830E; Wed, 12 Feb 2020 19:45:48 -0800 (PST) Received: from p8cg001049571a15.arm.com (unknown [10.163.1.114]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 54A743F68F; Wed, 12 Feb 2020 19:45:41 -0800 (PST) From: Anshuman Khandual To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, akpm@linux-foundation.org, catalin.marinas@arm.com, will@kernel.org Cc: mark.rutland@arm.com, david@redhat.com, cai@lca.pw, logang@deltatee.com, arunks@codeaurora.org, dan.j.williams@intel.com, mgorman@techsingularity.net, osalvador@suse.de, ard.biesheuvel@arm.com, steve.capper@arm.com, broonie@kernel.org, valentin.schneider@arm.com, Robin.Murphy@arm.com, steven.price@arm.com, suzuki.poulose@arm.com, ira.weiny@intel.com, anshuman.khandual@arm.com Subject: [PATCH V13 1/2] arm64/mm: Hold memory hotplug lock while walking for kernel page table dump Date: Thu, 13 Feb 2020 09:15:31 +0530 Message-Id: <1581565532-27916-2-git-send-email-anshuman.khandual@arm.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1581565532-27916-1-git-send-email-anshuman.khandual@arm.com> References: <1581565532-27916-1-git-send-email-anshuman.khandual@arm.com> 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: The arm64 page table dump code can race with concurrent modification of the kernel page tables. When a leaf entries are modified concurrently, the dump code may log stale or inconsistent information for a VA range, but this is otherwise not harmful. When intermediate levels of table are freed, the dump code will continue to use memory which has been freed and potentially reallocated for another purpose. In such cases, the dump code may dereference bogus addresses, leading to a number of potential problems. Intermediate levels of table may by freed during memory hot-remove, which will be enabled by a subsequent patch. To avoid racing with this, take the memory hotplug lock when walking the kernel page table. Acked-by: David Hildenbrand Acked-by: Mark Rutland Acked-by: Catalin Marinas Signed-off-by: Anshuman Khandual --- arch/arm64/mm/ptdump_debugfs.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/arm64/mm/ptdump_debugfs.c b/arch/arm64/mm/ptdump_debugfs.c index 1f2eae3..d29d722 100644 --- a/arch/arm64/mm/ptdump_debugfs.c +++ b/arch/arm64/mm/ptdump_debugfs.c @@ -1,5 +1,6 @@ // SPDX-License-Identifier: GPL-2.0 #include +#include #include #include @@ -7,7 +8,10 @@ static int ptdump_show(struct seq_file *m, void *v) { struct ptdump_info *info = m->private; + + get_online_mems(); ptdump_walk(m, info); + put_online_mems(); return 0; } DEFINE_SHOW_ATTRIBUTE(ptdump);