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=-9.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,T_DKIMWL_WL_HIGH,URIBL_BLOCKED,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 E8199C28CC0 for ; Wed, 29 May 2019 09:17:04 +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 BBD2420665 for ; Wed, 29 May 2019 09:17:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="LxZKso3g" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BBD2420665 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+infradead-linux-arm-kernel=archiver.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=Yi9uLQ+rkO1MqaaCciqJSFsJqavis/1rYGJuLi8LOK8=; b=LxZKso3g+yInYcoG1k3lZb62uH HRm/GWOgL7jhGrHBM5K6l5aj0Q0cNuACn+CqMVF5MAZ0+7lZFJkzoZ64HCJUKFiIfXOguc4bmuTMS TGSImE2LsaRKIy2votw4p6vzC/gPx1flnsz4Y2iI2Falk/fsluCQPaQ4khlCpyHGW9EJXylfblTh1 MYlcqVAKdtFKq+NdfZZuXKKpfcToSccaUCPK0kd2qz1Ghupk5/xEEtp7wn65+vUYisqyLDwDY1hf6 Gekg9DX/d7njSlIEPB5MqZlYIK044oUjKtwscWFbA5C/HzziC+pee9PrCBjGMLHN29/4WWegwj7zA BNhuretA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hVuhh-0008NK-Bi; Wed, 29 May 2019 09:17:01 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hVuhG-0007pJ-K3 for linux-arm-kernel@lists.infradead.org; Wed, 29 May 2019 09:16:38 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6E45D15AD; Wed, 29 May 2019 02:16:34 -0700 (PDT) Received: from p8cg001049571a15.blr.arm.com (p8cg001049571a15.blr.arm.com [10.162.41.181]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 2E2683F5AF; Wed, 29 May 2019 02:16:28 -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 V5 2/3] arm64/mm: Hold memory hotplug lock while walking for kernel page table dump Date: Wed, 29 May 2019 14:46:26 +0530 Message-Id: <1559121387-674-3-git-send-email-anshuman.khandual@arm.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1559121387-674-1-git-send-email-anshuman.khandual@arm.com> References: <1559121387-674-1-git-send-email-anshuman.khandual@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190529_021634_924213_4D4C29ED X-CRM114-Status: GOOD ( 13.58 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 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, 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 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.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. Acked-by: David Hildenbrand Signed-off-by: Anshuman Khandual --- arch/arm64/mm/ptdump_debugfs.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/arm64/mm/ptdump_debugfs.c b/arch/arm64/mm/ptdump_debugfs.c index 064163f..80171d1 100644 --- a/arch/arm64/mm/ptdump_debugfs.c +++ b/arch/arm64/mm/ptdump_debugfs.c @@ -7,7 +7,10 @@ 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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel