From patchwork Mon Jul 15 06:17:49 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anshuman Khandual X-Patchwork-Id: 11043395 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id F216F14DB for ; Mon, 15 Jul 2019 06:18:08 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E0E0D22362 for ; Mon, 15 Jul 2019 06:18:08 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D3D2A26D08; Mon, 15 Jul 2019 06:18:08 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 7959C22362 for ; Mon, 15 Jul 2019 06:18:08 +0000 (UTC) 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=lnXY+RzegAMgR3K4mMx+tqsuwvpxrAlLggGbMU80sN0=; b=IZSaSbqc5l2UYZkOlH39bDFZ6I NKhrOsdaKWijfUbkWhUfct1ESe2EKJ002nHyph55xKa45ZINUAMBAazGP6ottHmqn6I0zdjE6Mnwg FXJPdse1fJs5gxYKnz/u2s989p0Vj7+FOOg9rEP/CUqcx/u0TyBRG1jBzlmB9XW6zMhFhXgwFCNvX i0pXnuzZXcfqqwCMiI3XlmPeN34FanxL/EdUwnDr9SMfsFrV/CWqYUHLS/D9I1/WynHsbR7AlttPr /r8FvVZ3azofu18QJsldrghiyaB5Xe0ZRlljVlQZlSUp9Izt6CGxlZlqAs/WC54uu1RRCuWc58dDb PghNNGRg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hmuJL-0002Nr-Tn; Mon, 15 Jul 2019 06:18:08 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hmuIs-00020Y-Ih for linux-arm-kernel@lists.infradead.org; Mon, 15 Jul 2019 06:17:40 +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 9BEA0337; Sun, 14 Jul 2019 23:17:36 -0700 (PDT) Received: from p8cg001049571a15.blr.arm.com (p8cg001049571a15.blr.arm.com [10.162.40.143]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 6BE9F3F71F; Sun, 14 Jul 2019 23:19:30 -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.deacon@arm.com Subject: [PATCH V6 RESEND 2/3] arm64/mm: Hold memory hotplug lock while walking for kernel page table dump Date: Mon, 15 Jul 2019 11:47:49 +0530 Message-Id: <1563171470-3117-3-git-send-email-anshuman.khandual@arm.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1563171470-3117-1-git-send-email-anshuman.khandual@arm.com> References: <1563171470-3117-1-git-send-email-anshuman.khandual@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190714_231738_952040_809DAD13 X-CRM114-Status: GOOD ( 11.11 ) 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, mhocko@suse.com, david@redhat.com, ira.weiny@intel.com, steve.capper@arm.com, mgorman@techsingularity.net, cai@lca.pw, ard.biesheuvel@arm.com, cpandya@codeaurora.org, james.morse@arm.com, dan.j.williams@intel.com, logang@deltatee.com, arunks@codeaurora.org, 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 X-Virus-Scanned: ClamAV using ClamSMTP 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 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);