From patchwork Wed Oct 9 08:21:47 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anshuman Khandual X-Patchwork-Id: 11180715 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 0DBD11575 for ; Wed, 9 Oct 2019 08:21:52 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id CEAE4218AC for ; Wed, 9 Oct 2019 08:21:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CEAE4218AC 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 09DEA8E0006; Wed, 9 Oct 2019 04:21:51 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 027D38E0003; Wed, 9 Oct 2019 04:21:50 -0400 (EDT) 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 E30E68E0006; Wed, 9 Oct 2019 04:21:50 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0200.hostedemail.com [216.40.44.200]) by kanga.kvack.org (Postfix) with ESMTP id C00068E0003 for ; Wed, 9 Oct 2019 04:21:50 -0400 (EDT) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id 66BF0181AC9B4 for ; Wed, 9 Oct 2019 08:21:50 +0000 (UTC) X-FDA: 76023552780.18.mice67_2d13c573d2000 X-Spam-Summary: 2,0,0,f8abca35ad51db9a,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:cpandya@codeaurora.org: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,RULES_HIT:41:355:379:541:800:960:966:968:973:988:989:1260:1261:1345:1359:1431:1437:1534:1541:1711:1730:1747:1777:1792:1963:2194:2196:2199:2200:2393:2553:2559:2562:2693:2892:2898:3138:3139:3140:3141:3142:3352:3865:3866:3867:3868:3870:3871:4250:4321:4385:5007:6261:6742:7903:8634:10004:11026:11473:11658:11914:12043:12048:12296:12297:12438:12555:12895:12986:13069:13153:13161:13228:13229:13255:13311:13357:14096:1418 1:14384: X-HE-Tag: mice67_2d13c573d2000 X-Filterd-Recvd-Size: 3209 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf23.hostedemail.com (Postfix) with ESMTP for ; Wed, 9 Oct 2019 08:21:49 +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 9185E337; Wed, 9 Oct 2019 01:21:48 -0700 (PDT) Received: from p8cg001049571a15.blr.arm.com (p8cg001049571a15.blr.arm.com [10.162.43.141]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id DABB13F68E; Wed, 9 Oct 2019 01:21:41 -0700 (PDT) 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, cpandya@codeaurora.org, 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 Subject: [PATCH V9 1/2] arm64/mm: Hold memory hotplug lock while walking for kernel page table dump Date: Wed, 9 Oct 2019 13:51:47 +0530 Message-Id: <1570609308-15697-2-git-send-email-anshuman.khandual@arm.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1570609308-15697-1-git-send-email-anshuman.khandual@arm.com> References: <1570609308-15697-1-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 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 064163f25592..b5eebc8c4924 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_pgd(m, info); + put_online_mems(); return 0; } DEFINE_SHOW_ATTRIBUTE(ptdump);