From patchwork Fri Jan 10 03:09:14 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anshuman Khandual X-Patchwork-Id: 11326555 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 33E1A139A for ; Fri, 10 Jan 2020 03:09:42 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9AE4E20673 for ; Fri, 10 Jan 2020 03:09:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="MtEzMznb" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9AE4E20673 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=brcuZxRq0Bz6zxQdl/wCgLDFUPR7mr4KtnJNuC993/o=; b=MtEzMznbXweXVgPswomeaGnOSO eO6Bk8xjsL2Ya9s+7ytIvUGmbo51r9r+X0rLskQNIUqgbxm36X2+k4+q64pSzRLiWRoR1qiyiKWJr eiW+aXG+qfg4VBTo8vgpeqWkNRnLIlwwGbw2ecjfApqa7bN/43oe17ozMENWGGzZmIVaHTODjOrrL kZJvyhmemJD+rrMwy0343cQM0psev5AD7HfbjMedq4l62G4JnTfKjekhs7laHSAZHe86bsXwpScBa 5vS3EtMY0Lb/DdMOuUZlsg3J07Mk+UQkg1k4GD3t8RVVvuJhtZUYtUtOB+Ud992hrgSyUkq+OKYfa P6045siQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1ipkg6-0001Xt-H7; Fri, 10 Jan 2020 03:09:38 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1ipkfg-00018n-91 for linux-arm-kernel@lists.infradead.org; Fri, 10 Jan 2020 03:09:13 +0000 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 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> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200109_190912_385732_978F65D5 X-CRM114-Status: GOOD ( 11.39 ) X-Spam-Score: 0.0 (/) X-Spam-Report: SpamAssassin version 3.4.2 on bombadil.infradead.org summary: Content analysis details: (0.0 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at https://www.dnswl.org/, no trust [217.140.110.172 listed in list.dnswl.org] 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, ira.weiny@intel.com, david@redhat.com, mgorman@techsingularity.net, steve.capper@arm.com, Robin.Murphy@arm.com, steven.price@arm.com, broonie@kernel.org, cai@lca.pw, ard.biesheuvel@arm.com, cpandya@codeaurora.org, arunks@codeaurora.org, dan.j.williams@intel.com, Anshuman Khandual , logang@deltatee.com, valentin.schneider@arm.com, suzuki.poulose@arm.com, osalvador@suse.de MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.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);