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Tue, 21 Jan 2020 12:02:41 +0000 Received: from arrakis.emea.arm.com (217.140.106.50) by LO2P265CA0134.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:9f::26) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2644.20 via Frontend Transport; Tue, 21 Jan 2020 12:02:40 +0000 From: Catalin Marinas To: Anshuman Khandual Subject: Re: [PATCH V12 1/2] arm64/mm: Hold memory hotplug lock while walking for kernel page table dump Thread-Topic: [PATCH V12 1/2] arm64/mm: Hold memory hotplug lock while walking for kernel page table dump Thread-Index: AQHVzDhxBbGg9NtlH0u/OUhHsvtVxKf1DOgA Date: Tue, 21 Jan 2020 12:02:41 +0000 Message-ID: <20200121120238.GC3113562@arrakis.emea.arm.com> References: <1579157135-10360-1-git-send-email-anshuman.khandual@arm.com> <1579157135-10360-2-git-send-email-anshuman.khandual@arm.com> In-Reply-To: <1579157135-10360-2-git-send-email-anshuman.khandual@arm.com> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [217.140.106.50] x-clientproxiedby: LO2P265CA0134.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:9f::26) To DB6PR08MB2791.eurprd08.prod.outlook.com (2603:10a6:6:17::32) Authentication-Results-Original: spf=none (sender IP is ) smtp.mailfrom=Catalin.Marinas@arm.com; 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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 Thu, Jan 16, 2020 at 12:15:34PM +0530, Anshuman Khandual wrote: > 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 Acked-by: Catalin Marinas IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you. IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel