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=-4.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS 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 DFCDEC04AB4 for ; Wed, 15 May 2019 01:56:41 +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 A17B320862 for ; Wed, 15 May 2019 01:56:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="l7nv/yCu" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A17B320862 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:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:To:Subject:Reply-To:Content-ID:Content-Description :Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=SNv/JZWReAFcLUSPDeEQT71V/AyD4ocggeRl3v7KWLo=; b=l7nv/yCuxTePah BLYHLc0JvoM6zL5fSWavXKAR6MgVMwe4rZTprAAwhZjj+yK9L6NdUfcZxi5Bk2kTLANjt48r839ro MJD2XEHzvbtTqxjQtNL1/gv1VL8ycW1I8H++ht4/gn6VF29sYtobbqSOZvzvtJhyUMMWuD0lL3ZbE srpQak4BleeKFnNU/StQHIbYpOiydBM90xJ/IV0028Qg2HpEUk4x4H/5N5HDsS7zNh5dpQcJk8PI4 An9Gb6bVXE3qqEjPW8EecEKKamP2XKKC5CGcQeKN/mQSfKT7nqB4DC3eZLVHLIHghCKw6zE7YOwrB bdWnmqg9rOMiVrTh29qQ==; 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 1hQj9p-0007qt-7r; Wed, 15 May 2019 01:56:37 +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 1hQj9l-0007px-JI for linux-arm-kernel@lists.infradead.org; Wed, 15 May 2019 01:56:35 +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 60CE1374; Tue, 14 May 2019 18:56:32 -0700 (PDT) Received: from [10.163.1.137] (unknown [10.163.1.137]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 6AED13F71E; Tue, 14 May 2019 18:56:23 -0700 (PDT) Subject: Re: [PATCH V3 2/4] arm64/mm: Hold memory hotplug lock while walking for kernel page table dump To: Mark Rutland References: <1557824407-19092-1-git-send-email-anshuman.khandual@arm.com> <1557824407-19092-3-git-send-email-anshuman.khandual@arm.com> <20190514154000.GA20935@lakrids.cambridge.arm.com> From: Anshuman Khandual Message-ID: <107ce10f-622c-7914-6269-cff5509b084f@arm.com> Date: Wed, 15 May 2019 07:26:32 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20190514154000.GA20935@lakrids.cambridge.arm.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190514_185633_641883_53EEB735 X-CRM114-Status: GOOD ( 17.02 ) 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: cai@lca.pw, mhocko@suse.com, ira.weiny@intel.com, david@redhat.com, catalin.marinas@arm.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, logang@deltatee.com, james.morse@arm.com, cpandya@codeaurora.org, arunks@codeaurora.org, akpm@linux-foundation.org, osalvador@suse.de, mgorman@techsingularity.net, dan.j.williams@intel.com, linux-arm-kernel@lists.infradead.org, robin.murphy@arm.com 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 On 05/14/2019 09:10 PM, Mark Rutland wrote: > On Tue, May 14, 2019 at 02:30:05PM +0530, Anshuman Khandual wrote: >> The arm64 pagetable 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 addressses, >> leading to a number of potential problems. >> >> Intermediate levels of table may by freed during memory hot-remove, or when >> installing a huge mapping in the vmalloc region. To avoid racing with these >> cases, take the memory hotplug lock when walking the kernel page table. >> >> Signed-off-by: Anshuman Khandual > Can we please move this after the next patch (which addresses the huge > vmap case), and change the last paragraph to: > > 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. > > With that, this looks good to me. Sure will do. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel