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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT 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 BEDC6C3F68F for ; Fri, 10 Jan 2020 03:09:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A10C52073A for ; Fri, 10 Jan 2020 03:09:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731114AbgAJDJM (ORCPT ); Thu, 9 Jan 2020 22:09:12 -0500 Received: from foss.arm.com ([217.140.110.172]:39080 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730952AbgAJDJM (ORCPT ); Thu, 9 Jan 2020 22:09:12 -0500 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 9BF3A11FB; Thu, 9 Jan 2020 19:09:11 -0800 (PST) Received: from p8cg001049571a15.blr.arm.com (p8cg001049571a15.blr.arm.com [10.162.42.128]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 988163F703; Thu, 9 Jan 2020 19:09:05 -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, 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, Anshuman Khandual Subject: [PATCH V11 4/5] arm64/mm: Hold memory hotplug lock while walking for kernel page table dump Date: Fri, 10 Jan 2020 08:39:14 +0530 Message-Id: <1578625755-11792-5-git-send-email-anshuman.khandual@arm.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1578625755-11792-1-git-send-email-anshuman.khandual@arm.com> References: <1578625755-11792-1-git-send-email-anshuman.khandual@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Cc: Catalin Marinas Cc: Will Deacon 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 064163f..b5eebc8 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); -- 2.7.4