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Mon, 30 Mar 2020 13:23:05 +0000 (UTC) Received: from [10.36.113.227] (ovpn-113-227.ams2.redhat.com [10.36.113.227]) by smtp.corp.redhat.com (Postfix) with ESMTP id A10835C1B5; Mon, 30 Mar 2020 13:23:02 +0000 (UTC) Subject: Re: [PATCH 2/3] mm/memory_hotplug: Allow arch override of non boot memory resource names To: James Morse Cc: kexec@lists.infradead.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, Eric Biederman , Andrew Morton , Catalin Marinas , Will Deacon , Anshuman Khandual , Bhupesh Sharma , Vitaly Kuznetsov References: <20200326180730.4754-1-james.morse@arm.com> <20200326180730.4754-3-james.morse@arm.com> <52d6fd33-c15d-b842-84ed-b4a74265199f@redhat.com> <25aa3f43-5aa9-653f-0910-dd7b75527e08@arm.com> From: David Hildenbrand 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: <1090cc16-fa6b-8dd2-8c41-22136f733f00@redhat.com> Date: Mon, 30 Mar 2020 15:23:01 +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: <25aa3f43-5aa9-653f-0910-dd7b75527e08@arm.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit 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: >>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c >>> index 0a54ffac8c68..69b03dd7fc74 100644 >>> --- a/mm/memory_hotplug.c >>> +++ b/mm/memory_hotplug.c >>> @@ -42,6 +42,10 @@ >>> #include "internal.h" >>> #include "shuffle.h" >>> >>> +#ifndef MEMORY_HOTPLUG_RES_NAME >>> +#define MEMORY_HOTPLUG_RES_NAME "System RAM" >>> +#endif >> >> So I assume changing this for all architectures would result in some >> user space tool breaking? Are we aware of any? > > Last time we had to touch arm64's /proc/iomem strings I went through debian's > codesearch for stuff that reads it, kexec-tools was the only thing that parsed > it in anger. (From memory, the other tools were looking for PCIe windows to do > firmware flashing..) > > Looking again, having qualifiers on the end of 'System RAM' looks like it could > confuse 's390-tools's detect_mem_chunks parser. Good to know, we should find out if this could work. > > It looks like the strings that come out of 'FIRMWARE_MEMMAP' are a duplicate set. > > >> I do wonder if we should simply change it for all architectures if possible. > > If its possible that would be great. But I suspect that ship has sailed, > changing it on other architectures could break some fragile parsing code. I assume any parser has to be prepared for new types showing up. Otherwise these would not be future proof. The question is if a common prefix is problematic. E.g., Use "Hotplugged System RAM" instead of "System RAM (hotplug)" > > I'm wary of changing it on arm64, the only thing that makes it tolerable is that > memory hot-add was relatively recently merged, and we don't anticipate it being > widely used until you can remove memory as well. > > Changing it on arm64 is to prevent today's versions of kexec-tools from > accidentally placing the new kernel in memory that wasn't described at boot. > This leads to an unhandled exception during boot[0] because the kernel can't > access itself via the mapping of all memory. (hotpluggable regions are only > discovered by suitably configured ACPI systems much later) I want the very same for virtio-mem (initially x86-only, but later open for all archs). Can also be interesting for Hyper-V. kexec should not try to use hotplugged memory as kexec target, as memory blocks can be partially inaccessible. Of course, I can provide an interface to override the name via add_memory(), but having it on all architectures handled in a similar way right from the start would be nicer. -- 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=-5.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 37331C43331 for ; Mon, 30 Mar 2020 13:23:16 +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 0D91B20757 for ; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <25aa3f43-5aa9-653f-0910-dd7b75527e08@arm.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 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-20200330_062311_729395_6829F350 X-CRM114-Status: GOOD ( 19.86 ) 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, Eric Biederman , Andrew Morton , Will Deacon , Vitaly Kuznetsov , 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 >>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c >>> index 0a54ffac8c68..69b03dd7fc74 100644 >>> --- a/mm/memory_hotplug.c >>> +++ b/mm/memory_hotplug.c >>> @@ -42,6 +42,10 @@ >>> #include "internal.h" >>> #include "shuffle.h" >>> >>> +#ifndef MEMORY_HOTPLUG_RES_NAME >>> +#define MEMORY_HOTPLUG_RES_NAME "System RAM" >>> +#endif >> >> So I assume changing this for all architectures would result in some >> user space tool breaking? Are we aware of any? > > Last time we had to touch arm64's /proc/iomem strings I went through debian's > codesearch for stuff that reads it, kexec-tools was the only thing that parsed > it in anger. (From memory, the other tools were looking for PCIe windows to do > firmware flashing..) > > Looking again, having qualifiers on the end of 'System RAM' looks like it could > confuse 's390-tools's detect_mem_chunks parser. Good to know, we should find out if this could work. > > It looks like the strings that come out of 'FIRMWARE_MEMMAP' are a duplicate set. > > >> I do wonder if we should simply change it for all architectures if possible. > > If its possible that would be great. But I suspect that ship has sailed, > changing it on other architectures could break some fragile parsing code. I assume any parser has to be prepared for new types showing up. Otherwise these would not be future proof. The question is if a common prefix is problematic. E.g., Use "Hotplugged System RAM" instead of "System RAM (hotplug)" > > I'm wary of changing it on arm64, the only thing that makes it tolerable is that > memory hot-add was relatively recently merged, and we don't anticipate it being > widely used until you can remove memory as well. > > Changing it on arm64 is to prevent today's versions of kexec-tools from > accidentally placing the new kernel in memory that wasn't described at boot. > This leads to an unhandled exception during boot[0] because the kernel can't > access itself via the mapping of all memory. (hotpluggable regions are only > discovered by suitably configured ACPI systems much later) I want the very same for virtio-mem (initially x86-only, but later open for all archs). Can also be interesting for Hyper-V. kexec should not try to use hotplugged memory as kexec target, as memory blocks can be partially inaccessible. Of course, I can provide an interface to override the name via add_memory(), but having it on all architectures handled in a similar way right from the start would be nicer. -- Thanks, David / dhildenb _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel