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Biederman" , Russell King - ARM Linux admin , Anshuman Khandual , Catalin Marinas , Bhupesh Sharma , kexec@lists.infradead.org, linux-mm@kvack.org, James Morse , Will Deacon , linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, piliu@redhat.com References: <20200414064031.GB4247@MiWiFi-R3L-srv> <86e96214-7053-340b-5c1a-ff97fb94d8e0@redhat.com> <20200414092201.GD4247@MiWiFi-R3L-srv> <20200414143912.GE4247@MiWiFi-R3L-srv> <0085f460-b0c7-b25f-36a7-fa3bafaab6fe@redhat.com> <20200415023524.GG4247@MiWiFi-R3L-srv> <18cf6afd-c651-25c7-aca3-3ca3c0e07547@redhat.com> <20200416140247.GA12723@MiWiFi-R3L-srv> <4e1546eb-4416-dc6d-d549-62d1cecccbc8@redhat.com> <20200416143634.GH4247@MiWiFi-R3L-srv> <2525cc9c-3566-6275-105b-7f4af8f980bc@redhat.com> Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= mQINBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABtCREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT6JAlgEEwEIAEICGwMFCQlmAYAGCwkIBwMCBhUI AgkKCwQWAgMBAh4BAheAFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl3pImkCGQEACgkQTd4Q 9wD/g1o+VA//SFvIHUAvul05u6wKv/pIR6aICPdpF9EIgEU448g+7FfDgQwcEny1pbEzAmiw zAXIQ9H0NZh96lcq+yDLtONnXk/bEYWHHUA014A1wqcYNRY8RvY1+eVHb0uu0KYQoXkzvu+s Dncuguk470XPnscL27hs8PgOP6QjG4jt75K2LfZ0eAqTOUCZTJxA8A7E9+XTYuU0hs7QVrWJ jQdFxQbRMrYz7uP8KmTK9/Cnvqehgl4EzyRaZppshruKMeyheBgvgJd5On1wWq4ZUV5PFM4x II3QbD3EJfWbaJMR55jI9dMFa+vK7MFz3rhWOkEx/QR959lfdRSTXdxs8V3zDvChcmRVGN8U Vo93d1YNtWnA9w6oCW1dnDZ4kgQZZSBIjp6iHcA08apzh7DPi08jL7M9UQByeYGr8KuR4i6e RZI6xhlZerUScVzn35ONwOC91VdYiQgjemiVLq1WDDZ3B7DIzUZ4RQTOaIWdtXBWb8zWakt/ ztGhsx0e39Gvt3391O1PgcA7ilhvqrBPemJrlb9xSPPRbaNAW39P8ws/UJnzSJqnHMVxbRZC Am4add/SM+OCP0w3xYss1jy9T+XdZa0lhUvJfLy7tNcjVG/sxkBXOaSC24MFPuwnoC9WvCVQ ZBxouph3kqc4Dt5X1EeXVLeba+466P1fe1rC8MbcwDkoUo65Ag0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAGJAiUEGAECAA8FAlXLn5ECGwwFCQlmAYAACgkQTd4Q 9wD/g1qA6w/+M+ggFv+JdVsz5+ZIc6MSyGUozASX+bmIuPeIecc9UsFRatc91LuJCKMkD9Uv GOcWSeFpLrSGRQ1Z7EMzFVU//qVs6uzhsNk0RYMyS0B6oloW3FpyQ+zOVylFWQCzoyyf227y GW8HnXunJSC+4PtlL2AY4yZjAVAPLK2l6mhgClVXTQ/S7cBoTQKP+jvVJOoYkpnFxWE9pn4t H5QIFk7Ip8TKr5k3fXVWk4lnUi9MTF/5L/mWqdyIO1s7cjharQCstfWCzWrVeVctpVoDfJWp 4LwTuQ5yEM2KcPeElLg5fR7WB2zH97oI6/Ko2DlovmfQqXh9xWozQt0iGy5tWzh6I0JrlcxJ ileZWLccC4XKD1037Hy2FLAjzfoWgwBLA6ULu0exOOdIa58H4PsXtkFPrUF980EEibUp0zFz GotRVekFAceUaRvAj7dh76cToeZkfsjAvBVb4COXuhgX6N4pofgNkW2AtgYu1nUsPAo+NftU CxrhjHtLn4QEBpkbErnXQyMjHpIatlYGutVMS91XTQXYydCh5crMPs7hYVsvnmGHIaB9ZMfB njnuI31KBiLUks+paRkHQlFcgS2N3gkRBzH7xSZ+t7Re3jvXdXEzKBbQ+dC3lpJB0wPnyMcX FOTT3aZT7IgePkt5iC/BKBk3hqKteTnJFeVIT7EC+a6YUFg= Organization: Red Hat GmbH Message-ID: <9a4eb1d7-33bf-8707-9c0c-1ca657c3e502@redhat.com> Date: Tue, 21 Apr 2020 15:29:37 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <2525cc9c-3566-6275-105b-7f4af8f980bc@redhat.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 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: >> ACPI SRAT is embeded into efi, need read out the rsdp pointer. If we don= 't >> pass the efi, it won't get the SRAT table correctly, if I remember >> correctly. Yeah, I remeber kvm guest can get memory hotplugged with >> ACPI only, this won't happen on bare metal though. Need check carefully.= =20 >> I have been using kvm guest with uefi firmwire recently. >=20 > Yeah, I can imagine that bare metal is different. kvm only uses ACPI. >=20 > I'm also asking because of virtio-mem. Memory added via virtio-mem is > not part of any efi tables or whatsoever. So I assume the kexec kernel > will not detect it automatically (good!), instead load the virtio-mem > driver and let it add memory back to the system. >=20 > I should probably play with kexec and virtio-mem once I have some spare > cycles ... to find out what's broken and needs to be addressed :) FWIW, I just gave virtio-mem and kexec/kdump a try. a) kdump seems to work. Memory added by virtio-mem is getting dumped. The kexec kernel only uses memory in the crash region. The virtio-mem driver properly bails out due to is_kdump_kernel(). b) "kexec -s -l" seems to work fine. For now, the kernel does not seem to get placed on virtio-mem memory (pure luck due to the left-to-right search). Memory added by virtio-mem is not getting added to the e820 map. Once the virtio-mem driver comes back up in the kexec kernel, the right memory is readded. c) "kexec -c -l" does not work properly. All memory added by virtio-mem is added to the e820 map, which is wrong. Memory that should not be touched will be touched by the kexec kernel. I assume kexec-tools just goes ahead and adds anything it can find in /proc/iomem (or /sys/firmware/memmap/) to the e820 map of the new kernel. Due to c), I assume all hotplugged memory (e.g., ACPI DIMMs) is similarly added to the e820 map and, therefore, won't be able to be onlined MOVABLE easily. At least for virtio-mem, I would either have to a) Not support "kexec -c -l". A viable option if we would be planning on not supporting it either way in the long term. I could block this in-kernel somehow eventually. b) Teach kexec-tools to leave virtio-mem added memory alone. E.g., by indicating it in /proc/iomem in a special way ("System RAM (hotplugged)"/"System RAM (virtio-mem)"). Baoquan, any opinion on that? --=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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 3D4FAC54FC9 for ; Tue, 21 Apr 2020 13:33:07 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (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 9A9A6206F4 for ; Tue, 21 Apr 2020 13:33:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="DXXJAgc0"; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <2525cc9c-3566-6275-105b-7f4af8f980bc@redhat.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: piliu@redhat.com, Anshuman Khandual , Catalin Marinas , Bhupesh Sharma , linuxppc-dev@lists.ozlabs.org, kexec@lists.infradead.org, Russell King - ARM Linux admin , linux-mm@kvack.org, James Morse , "Eric W. Biederman" , Will Deacon , linux-arm-kernel@lists.infradead.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" >> ACPI SRAT is embeded into efi, need read out the rsdp pointer. If we don= 't >> pass the efi, it won't get the SRAT table correctly, if I remember >> correctly. Yeah, I remeber kvm guest can get memory hotplugged with >> ACPI only, this won't happen on bare metal though. Need check carefully.= =20 >> I have been using kvm guest with uefi firmwire recently. >=20 > Yeah, I can imagine that bare metal is different. kvm only uses ACPI. >=20 > I'm also asking because of virtio-mem. Memory added via virtio-mem is > not part of any efi tables or whatsoever. So I assume the kexec kernel > will not detect it automatically (good!), instead load the virtio-mem > driver and let it add memory back to the system. >=20 > I should probably play with kexec and virtio-mem once I have some spare > cycles ... to find out what's broken and needs to be addressed :) FWIW, I just gave virtio-mem and kexec/kdump a try. a) kdump seems to work. Memory added by virtio-mem is getting dumped. The kexec kernel only uses memory in the crash region. The virtio-mem driver properly bails out due to is_kdump_kernel(). b) "kexec -s -l" seems to work fine. For now, the kernel does not seem to get placed on virtio-mem memory (pure luck due to the left-to-right search). Memory added by virtio-mem is not getting added to the e820 map. Once the virtio-mem driver comes back up in the kexec kernel, the right memory is readded. c) "kexec -c -l" does not work properly. All memory added by virtio-mem is added to the e820 map, which is wrong. Memory that should not be touched will be touched by the kexec kernel. I assume kexec-tools just goes ahead and adds anything it can find in /proc/iomem (or /sys/firmware/memmap/) to the e820 map of the new kernel. Due to c), I assume all hotplugged memory (e.g., ACPI DIMMs) is similarly added to the e820 map and, therefore, won't be able to be onlined MOVABLE easily. At least for virtio-mem, I would either have to a) Not support "kexec -c -l". A viable option if we would be planning on not supporting it either way in the long term. I could block this in-kernel somehow eventually. b) Teach kexec-tools to leave virtio-mem added memory alone. E.g., by indicating it in /proc/iomem in a special way ("System RAM (hotplugged)"/"System RAM (virtio-mem)"). 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Tue, 21 Apr 2020 09:29:45 -0400 X-MC-Unique: OThd0_ElPwOBFSpFpv7rGA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D575C107BA97; Tue, 21 Apr 2020 13:29:43 +0000 (UTC) Received: from [10.36.113.245] (ovpn-113-245.ams2.redhat.com [10.36.113.245]) by smtp.corp.redhat.com (Postfix) with ESMTP id 51D6E76E68; Tue, 21 Apr 2020 13:29:38 +0000 (UTC) Subject: Re: [PATCH 1/3] kexec: Prevent removal of memory in use by a loaded kexec image From: David Hildenbrand To: Baoquan He , Andrew Morton References: <20200414064031.GB4247@MiWiFi-R3L-srv> <86e96214-7053-340b-5c1a-ff97fb94d8e0@redhat.com> <20200414092201.GD4247@MiWiFi-R3L-srv> <20200414143912.GE4247@MiWiFi-R3L-srv> <0085f460-b0c7-b25f-36a7-fa3bafaab6fe@redhat.com> <20200415023524.GG4247@MiWiFi-R3L-srv> <18cf6afd-c651-25c7-aca3-3ca3c0e07547@redhat.com> <20200416140247.GA12723@MiWiFi-R3L-srv> <4e1546eb-4416-dc6d-d549-62d1cecccbc8@redhat.com> <20200416143634.GH4247@MiWiFi-R3L-srv> <2525cc9c-3566-6275-105b-7f4af8f980bc@redhat.com> 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: <2525cc9c-3566-6275-105b-7f4af8f980bc@redhat.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 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-20200421_062950_771250_13A5FED3 X-CRM114-Status: GOOD ( 19.37 ) 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: piliu@redhat.com, Anshuman Khandual , Catalin Marinas , Bhupesh Sharma , linuxppc-dev@lists.ozlabs.org, kexec@lists.infradead.org, Russell King - ARM Linux admin , linux-mm@kvack.org, James Morse , "Eric W. 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 >> ACPI SRAT is embeded into efi, need read out the rsdp pointer. If we don't >> pass the efi, it won't get the SRAT table correctly, if I remember >> correctly. Yeah, I remeber kvm guest can get memory hotplugged with >> ACPI only, this won't happen on bare metal though. Need check carefully. >> I have been using kvm guest with uefi firmwire recently. > > Yeah, I can imagine that bare metal is different. kvm only uses ACPI. > > I'm also asking because of virtio-mem. Memory added via virtio-mem is > not part of any efi tables or whatsoever. So I assume the kexec kernel > will not detect it automatically (good!), instead load the virtio-mem > driver and let it add memory back to the system. > > I should probably play with kexec and virtio-mem once I have some spare > cycles ... to find out what's broken and needs to be addressed :) FWIW, I just gave virtio-mem and kexec/kdump a try. a) kdump seems to work. Memory added by virtio-mem is getting dumped. The kexec kernel only uses memory in the crash region. The virtio-mem driver properly bails out due to is_kdump_kernel(). b) "kexec -s -l" seems to work fine. For now, the kernel does not seem to get placed on virtio-mem memory (pure luck due to the left-to-right search). Memory added by virtio-mem is not getting added to the e820 map. Once the virtio-mem driver comes back up in the kexec kernel, the right memory is readded. c) "kexec -c -l" does not work properly. All memory added by virtio-mem is added to the e820 map, which is wrong. Memory that should not be touched will be touched by the kexec kernel. I assume kexec-tools just goes ahead and adds anything it can find in /proc/iomem (or /sys/firmware/memmap/) to the e820 map of the new kernel. Due to c), I assume all hotplugged memory (e.g., ACPI DIMMs) is similarly added to the e820 map and, therefore, won't be able to be onlined MOVABLE easily. At least for virtio-mem, I would either have to a) Not support "kexec -c -l". A viable option if we would be planning on not supporting it either way in the long term. I could block this in-kernel somehow eventually. b) Teach kexec-tools to leave virtio-mem added memory alone. E.g., by indicating it in /proc/iomem in a special way ("System RAM (hotplugged)"/"System RAM (virtio-mem)"). Baoquan, any opinion on that? -- 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 1jQsyE-0003vw-Me for kexec@lists.infradead.org; Tue, 21 Apr 2020 13:29:53 +0000 Subject: Re: [PATCH 1/3] kexec: Prevent removal of memory in use by a loaded kexec image From: David Hildenbrand References: <20200414064031.GB4247@MiWiFi-R3L-srv> <86e96214-7053-340b-5c1a-ff97fb94d8e0@redhat.com> <20200414092201.GD4247@MiWiFi-R3L-srv> <20200414143912.GE4247@MiWiFi-R3L-srv> <0085f460-b0c7-b25f-36a7-fa3bafaab6fe@redhat.com> <20200415023524.GG4247@MiWiFi-R3L-srv> <18cf6afd-c651-25c7-aca3-3ca3c0e07547@redhat.com> <20200416140247.GA12723@MiWiFi-R3L-srv> <4e1546eb-4416-dc6d-d549-62d1cecccbc8@redhat.com> <20200416143634.GH4247@MiWiFi-R3L-srv> <2525cc9c-3566-6275-105b-7f4af8f980bc@redhat.com> Message-ID: <9a4eb1d7-33bf-8707-9c0c-1ca657c3e502@redhat.com> Date: Tue, 21 Apr 2020 15:29:37 +0200 MIME-Version: 1.0 In-Reply-To: <2525cc9c-3566-6275-105b-7f4af8f980bc@redhat.com> 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: Baoquan He , Andrew Morton Cc: piliu@redhat.com, Anshuman Khandual , Catalin Marinas , Bhupesh Sharma , linuxppc-dev@lists.ozlabs.org, kexec@lists.infradead.org, Russell King - ARM Linux admin , linux-mm@kvack.org, James Morse , "Eric W. Biederman" , Will Deacon , linux-arm-kernel@lists.infradead.org >> ACPI SRAT is embeded into efi, need read out the rsdp pointer. If we don't >> pass the efi, it won't get the SRAT table correctly, if I remember >> correctly. Yeah, I remeber kvm guest can get memory hotplugged with >> ACPI only, this won't happen on bare metal though. Need check carefully. >> I have been using kvm guest with uefi firmwire recently. > > Yeah, I can imagine that bare metal is different. kvm only uses ACPI. > > I'm also asking because of virtio-mem. Memory added via virtio-mem is > not part of any efi tables or whatsoever. So I assume the kexec kernel > will not detect it automatically (good!), instead load the virtio-mem > driver and let it add memory back to the system. > > I should probably play with kexec and virtio-mem once I have some spare > cycles ... to find out what's broken and needs to be addressed :) FWIW, I just gave virtio-mem and kexec/kdump a try. a) kdump seems to work. Memory added by virtio-mem is getting dumped. The kexec kernel only uses memory in the crash region. The virtio-mem driver properly bails out due to is_kdump_kernel(). b) "kexec -s -l" seems to work fine. For now, the kernel does not seem to get placed on virtio-mem memory (pure luck due to the left-to-right search). Memory added by virtio-mem is not getting added to the e820 map. Once the virtio-mem driver comes back up in the kexec kernel, the right memory is readded. c) "kexec -c -l" does not work properly. All memory added by virtio-mem is added to the e820 map, which is wrong. Memory that should not be touched will be touched by the kexec kernel. I assume kexec-tools just goes ahead and adds anything it can find in /proc/iomem (or /sys/firmware/memmap/) to the e820 map of the new kernel. Due to c), I assume all hotplugged memory (e.g., ACPI DIMMs) is similarly added to the e820 map and, therefore, won't be able to be onlined MOVABLE easily. At least for virtio-mem, I would either have to a) Not support "kexec -c -l". A viable option if we would be planning on not supporting it either way in the long term. I could block this in-kernel somehow eventually. b) Teach kexec-tools to leave virtio-mem added memory alone. E.g., by indicating it in /proc/iomem in a special way ("System RAM (hotplugged)"/"System RAM (virtio-mem)"). Baoquan, any opinion on that? -- Thanks, David / dhildenb _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec