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Tue, 14 Apr 2020 07:05:21 +0000 (UTC) Received: from [10.36.113.201] (ovpn-113-201.ams2.redhat.com [10.36.113.201]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1CD831001DDE; Tue, 14 Apr 2020 07:05:18 +0000 (UTC) Subject: Re: [PATCH 1/3] kexec: Prevent removal of memory in use by a loaded kexec image To: Andrew Morton Cc: James Morse , kexec@lists.infradead.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, Eric Biederman , Catalin Marinas , Will Deacon , Anshuman Khandual , Bhupesh Sharma References: <20200326180730.4754-1-james.morse@arm.com> <20200326180730.4754-2-james.morse@arm.com> <321e6bf7-e898-7701-dd60-6c25237ff9cd@redhat.com> <9cb4ea0d-34c3-de42-4b3f-ee25a59c4835@redhat.com> <72672e2c-a57a-8df9-0cff-8035cbce7740@redhat.com> <34274b02-60ba-eb78-eacd-6dc1146ed3cd@arm.com> <80e4d1d7-f493-3f66-f700-86f18002d692@redhat.com> <20200410121013.03b609fd572504c03a666f4a@linux-foundation.org> From: David Hildenbrand Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200410121013.03b609fd572504c03a666f4a@linux-foundation.org> Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 10.04.20 21:10, Andrew Morton wrote: > It's unclear (to me) what is the status of this patchset. But it does ap= pear that > an new version can be expected? >=20 I'd suggest to unqueue the patches until we have a consensus. While there are a couple of ideas floating around here, my current suggestion would be either 1. Indicate all hotplugged memory as "System RAM (hotplugged)" in /proc/iomem and the firmware memmap (on all architectures). This will require kexec changes, but I would have assume that kexec has to be updated in lock-step with the kernel just like e.g., makedumpfile. Modify kexec() to not place the kexec kernel on these areas (easy) but still consider them as crash regions to dump. When loading a kexec kernel, validate in the kernel that the memory is appropriate. 2. Make kexec() reload the the kernel whenever we e.g., get a udev event for removal of memory in /sys/devices/system/memory/. On every remove_memory(), invalidate the loaded kernel in the kernel. As I mentioned somewhere, 1. will be interesting for virtio-mem, where we don't want any kexec kernel to be placed on virtio-mem-added memory. --=20 Thanks, David / dhildenb 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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 3C766C2BA19 for ; Tue, 14 Apr 2020 07:05:33 +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 0E659206E9 for ; Tue, 14 Apr 2020 07:05:33 +0000 (UTC) Authentication-Results: mail.kernel.org; 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bh=g0Dla9CLlUNdzYFH+u7BZDMPvnMBXFMPhcflTjD+Br4=; b=hjg8Gh52jZ4htZ1DEFBQijP2G08YYvnWaPX3HQYTpFFlb1DzlQ85Is0WlEcTHc3H+hkHOn NmehQOYRjEijcMAqvntvF3fud9uONJDCcxLtgKFiDgOA6BJLd6KjT3KbaMnYOII2Pml7JN X1Pd/OI9vQSc5ikT4fQKbzR1oQlSkdk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-460-Dgfv0QEqPKmsSHsvXQvz2w-1; Tue, 14 Apr 2020 03:05:23 -0400 X-MC-Unique: Dgfv0QEqPKmsSHsvXQvz2w-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 878B8107ACC4; Tue, 14 Apr 2020 07:05:21 +0000 (UTC) Received: from [10.36.113.201] (ovpn-113-201.ams2.redhat.com [10.36.113.201]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1CD831001DDE; Tue, 14 Apr 2020 07:05:18 +0000 (UTC) Subject: Re: [PATCH 1/3] kexec: Prevent removal of memory in use by a loaded kexec image To: Andrew Morton References: <20200326180730.4754-1-james.morse@arm.com> <20200326180730.4754-2-james.morse@arm.com> <321e6bf7-e898-7701-dd60-6c25237ff9cd@redhat.com> <9cb4ea0d-34c3-de42-4b3f-ee25a59c4835@redhat.com> <72672e2c-a57a-8df9-0cff-8035cbce7740@redhat.com> <34274b02-60ba-eb78-eacd-6dc1146ed3cd@arm.com> <80e4d1d7-f493-3f66-f700-86f18002d692@redhat.com> <20200410121013.03b609fd572504c03a666f4a@linux-foundation.org> From: David Hildenbrand Autocrypt: addr=david@redhat.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200410121013.03b609fd572504c03a666f4a@linux-foundation.org> Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200414_000528_793544_F3E389DF X-CRM114-Status: GOOD ( 13.30 ) 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: Anshuman Khandual , Catalin Marinas , Bhupesh Sharma , kexec@lists.infradead.org, linux-mm@kvack.org, James Morse , Eric Biederman , Will Deacon , linux-arm-kernel@lists.infradead.org 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 10.04.20 21:10, Andrew Morton wrote: > It's unclear (to me) what is the status of this patchset. But it does appear that > an new version can be expected? > I'd suggest to unqueue the patches until we have a consensus. While there are a couple of ideas floating around here, my current suggestion would be either 1. Indicate all hotplugged memory as "System RAM (hotplugged)" in /proc/iomem and the firmware memmap (on all architectures). This will require kexec changes, but I would have assume that kexec has to be updated in lock-step with the kernel just like e.g., makedumpfile. Modify kexec() to not place the kexec kernel on these areas (easy) but still consider them as crash regions to dump. When loading a kexec kernel, validate in the kernel that the memory is appropriate. 2. Make kexec() reload the the kernel whenever we e.g., get a udev event for removal of memory in /sys/devices/system/memory/. On every remove_memory(), invalidate the loaded kernel in the kernel. As I mentioned somewhere, 1. will be interesting for virtio-mem, where we don't want any kexec kernel to be placed on virtio-mem-added memory. -- Thanks, David / dhildenb _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120] helo=us-smtp-1.mimecast.com) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jOFdQ-0000BJ-FV for kexec@lists.infradead.org; Tue, 14 Apr 2020 07:05:29 +0000 Subject: Re: [PATCH 1/3] kexec: Prevent removal of memory in use by a loaded kexec image References: <20200326180730.4754-1-james.morse@arm.com> <20200326180730.4754-2-james.morse@arm.com> <321e6bf7-e898-7701-dd60-6c25237ff9cd@redhat.com> <9cb4ea0d-34c3-de42-4b3f-ee25a59c4835@redhat.com> <72672e2c-a57a-8df9-0cff-8035cbce7740@redhat.com> <34274b02-60ba-eb78-eacd-6dc1146ed3cd@arm.com> <80e4d1d7-f493-3f66-f700-86f18002d692@redhat.com> <20200410121013.03b609fd572504c03a666f4a@linux-foundation.org> From: David Hildenbrand Message-ID: <4ed2fa36-fcd8-7150-03d1-35f15e595ebb@redhat.com> Date: Tue, 14 Apr 2020 09:05:18 +0200 MIME-Version: 1.0 In-Reply-To: <20200410121013.03b609fd572504c03a666f4a@linux-foundation.org> Content-Language: en-US List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Andrew Morton Cc: Anshuman Khandual , Catalin Marinas , Bhupesh Sharma , kexec@lists.infradead.org, linux-mm@kvack.org, James Morse , Eric Biederman , Will Deacon , linux-arm-kernel@lists.infradead.org On 10.04.20 21:10, Andrew Morton wrote: > It's unclear (to me) what is the status of this patchset. But it does appear that > an new version can be expected? > I'd suggest to unqueue the patches until we have a consensus. While there are a couple of ideas floating around here, my current suggestion would be either 1. Indicate all hotplugged memory as "System RAM (hotplugged)" in /proc/iomem and the firmware memmap (on all architectures). This will require kexec changes, but I would have assume that kexec has to be updated in lock-step with the kernel just like e.g., makedumpfile. Modify kexec() to not place the kexec kernel on these areas (easy) but still consider them as crash regions to dump. When loading a kexec kernel, validate in the kernel that the memory is appropriate. 2. Make kexec() reload the the kernel whenever we e.g., get a udev event for removal of memory in /sys/devices/system/memory/. On every remove_memory(), invalidate the loaded kernel in the kernel. As I mentioned somewhere, 1. will be interesting for virtio-mem, where we don't want any kexec kernel to be placed on virtio-mem-added memory. -- Thanks, David / dhildenb _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec