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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 5FFF9C47255 for ; Thu, 30 Apr 2020 15:52:53 +0000 (UTC) Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (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 22A8520775 for ; Thu, 30 Apr 2020 15:52:52 +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="bKqV3FiW" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 22A8520775 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvdimm-bounces@lists.01.org Received: from ml01.vlan13.01.org (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 57882110EADE2; Thu, 30 Apr 2020 08:51:41 -0700 (PDT) Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=205.139.110.120; helo=us-smtp-1.mimecast.com; envelope-from=david@redhat.com; receiver= Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [205.139.110.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id CC9C3110BB05F for ; Thu, 30 Apr 2020 08:51:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588261968; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=OP9zUYIno6x6iC1SiniLiH6Fo13bK6xGgljySSJVtbc=; b=bKqV3FiWgZ7byRnIK2FziV/7tUnThpezxN6aBoPBCgUrQjLvuyyPejAoclGYGZ3PYX3mbC H6mhX9ZhKJLtMVqdwIRwOT53nWH6cmhFp/FQYdtdbIz0bYOQjIGTEVCBfQN5dlS/zsOKas cOqHPocWoI1ss14/qoZC5CQ+DWWQ6IM= 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-370-scg0K8IrNv2RPP-fweQOMw-1; Thu, 30 Apr 2020 11:52:44 -0400 X-MC-Unique: scg0K8IrNv2RPP-fweQOMw-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 694A264AD9; Thu, 30 Apr 2020 15:52:42 +0000 (UTC) Received: from [10.36.113.172] (ovpn-113-172.ams2.redhat.com [10.36.113.172]) by smtp.corp.redhat.com (Postfix) with ESMTP id 758B8605DE; Thu, 30 Apr 2020 15:52:36 +0000 (UTC) Subject: Re: [PATCH v2 2/3] mm/memory_hotplug: Introduce MHP_NO_FIRMWARE_MEMMAP To: "Eric W. Biederman" References: <20200430102908.10107-1-david@redhat.com> <20200430102908.10107-3-david@redhat.com> <87pnbp2dcz.fsf@x220.int.ebiederm.org> 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: <1b49c3be-6e2f-57cb-96f7-f66a8f8a9380@redhat.com> Date: Thu, 30 Apr 2020 17:52:35 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <87pnbp2dcz.fsf@x220.int.ebiederm.org> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Message-ID-Hash: 7JAHE5YFIFEZUZYPL5WFXESHNSARTPCE X-Message-ID-Hash: 7JAHE5YFIFEZUZYPL5WFXESHNSARTPCE X-MailFrom: david@redhat.com X-Mailman-Rule-Hits: nonmember-moderation X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation CC: linux-kernel@vger.kernel.org, linux-mm@kvack.org, virtio-dev@lists.oasis-open.org, virtualization@lists.linux-foundation.org, linuxppc-dev@lists.ozlabs.org, linux-acpi@vger.kernel.org, linux-nvdimm@lists.01.org, linux-hyperv@vger.kernel.org, linux-s390@vger.kernel.org, xen-devel@lists.xenproject.org, Michal Hocko , Andrew Morton , "Michael S . Tsirkin" , Michal Hocko , Pankaj Gupta , Wei Yang , Baoquan He X-Mailman-Version: 3.1.1 Precedence: list List-Id: "Linux-nvdimm developer list." Archived-At: List-Archive: List-Help: List-Post: List-Subscribe: List-Unsubscribe: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On 30.04.20 17:38, Eric W. Biederman wrote: > David Hildenbrand writes: > >> Some devices/drivers that add memory via add_memory() and friends (e.g., >> dax/kmem, but also virtio-mem in the future) don't want to create entries >> in /sys/firmware/memmap/ - primarily to hinder kexec from adding this >> memory to the boot memmap of the kexec kernel. >> >> In fact, such memory is never exposed via the firmware memmap as System >> RAM (e.g., e820), so exposing this memory via /sys/firmware/memmap/ is >> wrong: >> "kexec needs the raw firmware-provided memory map to setup the >> parameter segment of the kernel that should be booted with >> kexec. Also, the raw memory map is useful for debugging. For >> that reason, /sys/firmware/memmap is an interface that provides >> the raw memory map to userspace." [1] >> >> We don't have to worry about firmware_map_remove() on the removal path. >> If there is no entry, it will simply return with -EINVAL. >> >> [1] >> https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-firmware-memmap > > > You know what this justification is rubbish, and I have previously > explained why it is rubbish. Actually, no, I don't think it is rubbish. See patch #3 and the cover letter why this is the right thing to do *for special memory*, *not ordinary DIMMs*. And to be quite honest, I think your response is a little harsh. I don't recall you replying to my virtio-mem-related comments. > > Nacked-by: "Eric W. Biederman" > > This needs to be based on weather the added memory is ultimately normal > ram or is something special. Yes, that's what the caller are expected to decide, see patch #3. kexec should try to be as closely as possible to a real reboot - IMHO. > > At least when we are talking memory resources. Keeping it out of the > firmware map that is fine. > > If the hotplugged memory is the result of plugging a stick of ram > into the kernel and can and should used be like any other memory > it should be treated like any normal memory. > > If the hotplugged memory is something special it should be treated as > something special. I am really sorry, I can't make sense of what you are trying to say here. > > Justifying behavior by documentation that does not consider memory > hotplug is bad thinking. Are you maybe confusing this patch series with the arm64 approach? This is not about ordinary hotplugged DIMMs. I'd love to get Dan's, Dave's and Michal's opinion. -- Thanks, David / dhildenb _______________________________________________ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-leave@lists.01.org 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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 40CEAC47256 for ; Thu, 30 Apr 2020 15:52:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 19A082076D for ; Thu, 30 Apr 2020 15:52:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="bKqV3FiW" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726764AbgD3Pwx (ORCPT ); Thu, 30 Apr 2020 11:52:53 -0400 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:56369 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726960AbgD3Pwu (ORCPT ); Thu, 30 Apr 2020 11:52:50 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588261968; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=OP9zUYIno6x6iC1SiniLiH6Fo13bK6xGgljySSJVtbc=; b=bKqV3FiWgZ7byRnIK2FziV/7tUnThpezxN6aBoPBCgUrQjLvuyyPejAoclGYGZ3PYX3mbC H6mhX9ZhKJLtMVqdwIRwOT53nWH6cmhFp/FQYdtdbIz0bYOQjIGTEVCBfQN5dlS/zsOKas cOqHPocWoI1ss14/qoZC5CQ+DWWQ6IM= 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-370-scg0K8IrNv2RPP-fweQOMw-1; Thu, 30 Apr 2020 11:52:44 -0400 X-MC-Unique: scg0K8IrNv2RPP-fweQOMw-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 694A264AD9; Thu, 30 Apr 2020 15:52:42 +0000 (UTC) Received: from [10.36.113.172] (ovpn-113-172.ams2.redhat.com [10.36.113.172]) by smtp.corp.redhat.com (Postfix) with ESMTP id 758B8605DE; Thu, 30 Apr 2020 15:52:36 +0000 (UTC) Subject: Re: [PATCH v2 2/3] mm/memory_hotplug: Introduce MHP_NO_FIRMWARE_MEMMAP To: "Eric W. Biederman" Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, virtio-dev@lists.oasis-open.org, virtualization@lists.linux-foundation.org, linuxppc-dev@lists.ozlabs.org, linux-acpi@vger.kernel.org, linux-nvdimm@lists.01.org, linux-hyperv@vger.kernel.org, linux-s390@vger.kernel.org, xen-devel@lists.xenproject.org, Michal Hocko , Andrew Morton , "Michael S . Tsirkin" , Michal Hocko , Pankaj Gupta , Wei Yang , Baoquan He References: <20200430102908.10107-1-david@redhat.com> <20200430102908.10107-3-david@redhat.com> <87pnbp2dcz.fsf@x220.int.ebiederm.org> 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: <1b49c3be-6e2f-57cb-96f7-f66a8f8a9380@redhat.com> Date: Thu, 30 Apr 2020 17:52:35 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <87pnbp2dcz.fsf@x220.int.ebiederm.org> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Content-Transfer-Encoding: quoted-printable Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On 30.04.20 17:38, Eric W. Biederman wrote: > David Hildenbrand writes: >=20 >> Some devices/drivers that add memory via add_memory() and friends (e.g= ., >> dax/kmem, but also virtio-mem in the future) don't want to create entr= ies >> in /sys/firmware/memmap/ - primarily to hinder kexec from adding this >> memory to the boot memmap of the kexec kernel. >> >> In fact, such memory is never exposed via the firmware memmap as Syste= m >> RAM (e.g., e820), so exposing this memory via /sys/firmware/memmap/ is >> wrong: >> "kexec needs the raw firmware-provided memory map to setup the >> parameter segment of the kernel that should be booted with >> kexec. Also, the raw memory map is useful for debugging. For >> that reason, /sys/firmware/memmap is an interface that provides >> the raw memory map to userspace." [1] >> >> We don't have to worry about firmware_map_remove() on the removal path= . >> If there is no entry, it will simply return with -EINVAL. >> >> [1] >> https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-firmware-me= mmap >=20 >=20 > You know what this justification is rubbish, and I have previously > explained why it is rubbish. Actually, no, I don't think it is rubbish. See patch #3 and the cover letter why this is the right thing to do *for special memory*, *not ordinary DIMMs*. And to be quite honest, I think your response is a little harsh. I don't recall you replying to my virtio-mem-related comments. >=20 > Nacked-by: "Eric W. Biederman" >=20 > This needs to be based on weather the added memory is ultimately normal > ram or is something special. Yes, that's what the caller are expected to decide, see patch #3. kexec should try to be as closely as possible to a real reboot - IMHO. >=20 > At least when we are talking memory resources. Keeping it out of the > firmware map that is fine. >=20 > If the hotplugged memory is the result of plugging a stick of ram > into the kernel and can and should used be like any other memory > it should be treated like any normal memory. >=20 > If the hotplugged memory is something special it should be treated as > something special. I am really sorry, I can't make sense of what you are trying to say here. >=20 > Justifying behavior by documentation that does not consider memory > hotplug is bad thinking. Are you maybe confusing this patch series with the arm64 approach? This is not about ordinary hotplugged DIMMs. I'd love to get Dan's, Dave's and Michal's opinion. --=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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 EAE05C4724C for ; Thu, 30 Apr 2020 15:56:16 +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 361CA2076D for ; Thu, 30 Apr 2020 15:56:16 +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="MaeNsOFP"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="MaeNsOFP" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 361CA2076D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 49Cg3J2F2NzDrCS for ; Fri, 1 May 2020 01:56:12 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=redhat.com (client-ip=205.139.110.120; helo=us-smtp-1.mimecast.com; envelope-from=david@redhat.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=MaeNsOFP; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=MaeNsOFP; dkim-atps=neutral Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [205.139.110.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 49CfzT6bhFzDr81 for ; Fri, 1 May 2020 01:52:52 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588261969; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=OP9zUYIno6x6iC1SiniLiH6Fo13bK6xGgljySSJVtbc=; b=MaeNsOFPzUdEg5kMeH8PcGlDdG0C8jBywQqzGykS59e2DBr6Tx96PwffEykq8hljtxMbmN AHqUg8Nh4p0eCjsIDiPP7ZNhoKhtZExbUa+odC/w+QiwLSl6T3qHLhdg+/y2DMBpO4nx3e V/fXqjSadZp8Np8uixjih65JaqXZvJw= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588261969; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=OP9zUYIno6x6iC1SiniLiH6Fo13bK6xGgljySSJVtbc=; b=MaeNsOFPzUdEg5kMeH8PcGlDdG0C8jBywQqzGykS59e2DBr6Tx96PwffEykq8hljtxMbmN AHqUg8Nh4p0eCjsIDiPP7ZNhoKhtZExbUa+odC/w+QiwLSl6T3qHLhdg+/y2DMBpO4nx3e V/fXqjSadZp8Np8uixjih65JaqXZvJw= 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-370-scg0K8IrNv2RPP-fweQOMw-1; Thu, 30 Apr 2020 11:52:44 -0400 X-MC-Unique: scg0K8IrNv2RPP-fweQOMw-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 694A264AD9; Thu, 30 Apr 2020 15:52:42 +0000 (UTC) Received: from [10.36.113.172] (ovpn-113-172.ams2.redhat.com [10.36.113.172]) by smtp.corp.redhat.com (Postfix) with ESMTP id 758B8605DE; Thu, 30 Apr 2020 15:52:36 +0000 (UTC) Subject: Re: [PATCH v2 2/3] mm/memory_hotplug: Introduce MHP_NO_FIRMWARE_MEMMAP To: "Eric W. Biederman" References: <20200430102908.10107-1-david@redhat.com> <20200430102908.10107-3-david@redhat.com> <87pnbp2dcz.fsf@x220.int.ebiederm.org> 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: <1b49c3be-6e2f-57cb-96f7-f66a8f8a9380@redhat.com> Date: Thu, 30 Apr 2020 17:52:35 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <87pnbp2dcz.fsf@x220.int.ebiederm.org> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 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: virtio-dev@lists.oasis-open.org, linux-hyperv@vger.kernel.org, Michal Hocko , Baoquan He , linux-mm@kvack.org, Wei Yang , linux-s390@vger.kernel.org, linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-acpi@vger.kernel.org, "Michael S . Tsirkin" , Pankaj Gupta , xen-devel@lists.xenproject.org, Andrew Morton , Michal Hocko , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 30.04.20 17:38, Eric W. Biederman wrote: > David Hildenbrand writes: >=20 >> Some devices/drivers that add memory via add_memory() and friends (e.g= ., >> dax/kmem, but also virtio-mem in the future) don't want to create entr= ies >> in /sys/firmware/memmap/ - primarily to hinder kexec from adding this >> memory to the boot memmap of the kexec kernel. >> >> In fact, such memory is never exposed via the firmware memmap as Syste= m >> RAM (e.g., e820), so exposing this memory via /sys/firmware/memmap/ is >> wrong: >> "kexec needs the raw firmware-provided memory map to setup the >> parameter segment of the kernel that should be booted with >> kexec. Also, the raw memory map is useful for debugging. For >> that reason, /sys/firmware/memmap is an interface that provides >> the raw memory map to userspace." [1] >> >> We don't have to worry about firmware_map_remove() on the removal path= . >> If there is no entry, it will simply return with -EINVAL. >> >> [1] >> https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-firmware-me= mmap >=20 >=20 > You know what this justification is rubbish, and I have previously > explained why it is rubbish. Actually, no, I don't think it is rubbish. See patch #3 and the cover letter why this is the right thing to do *for special memory*, *not ordinary DIMMs*. And to be quite honest, I think your response is a little harsh. I don't recall you replying to my virtio-mem-related comments. >=20 > Nacked-by: "Eric W. Biederman" >=20 > This needs to be based on weather the added memory is ultimately normal > ram or is something special. Yes, that's what the caller are expected to decide, see patch #3. kexec should try to be as closely as possible to a real reboot - IMHO. >=20 > At least when we are talking memory resources. Keeping it out of the > firmware map that is fine. >=20 > If the hotplugged memory is the result of plugging a stick of ram > into the kernel and can and should used be like any other memory > it should be treated like any normal memory. >=20 > If the hotplugged memory is something special it should be treated as > something special. I am really sorry, I can't make sense of what you are trying to say here. >=20 > Justifying behavior by documentation that does not consider memory > hotplug is bad thinking. Are you maybe confusing this patch series with the arm64 approach? This is not about ordinary hotplugged DIMMs. I'd love to get Dan's, Dave's and Michal's opinion. --=20 Thanks, David / dhildenb From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-dev-return-7226-cohuck=redhat.com@lists.oasis-open.org Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id A7224985B78 for ; Thu, 30 Apr 2020 15:52:48 +0000 (UTC) References: <20200430102908.10107-1-david@redhat.com> <20200430102908.10107-3-david@redhat.com> <87pnbp2dcz.fsf@x220.int.ebiederm.org> From: David Hildenbrand Message-ID: <1b49c3be-6e2f-57cb-96f7-f66a8f8a9380@redhat.com> Date: Thu, 30 Apr 2020 17:52:35 +0200 MIME-Version: 1.0 In-Reply-To: <87pnbp2dcz.fsf@x220.int.ebiederm.org> Content-Language: en-US Subject: [virtio-dev] Re: [PATCH v2 2/3] mm/memory_hotplug: Introduce MHP_NO_FIRMWARE_MEMMAP Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable To: "Eric W. Biederman" Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, virtio-dev@lists.oasis-open.org, virtualization@lists.linux-foundation.org, linuxppc-dev@lists.ozlabs.org, linux-acpi@vger.kernel.org, linux-nvdimm@lists.01.org, linux-hyperv@vger.kernel.org, linux-s390@vger.kernel.org, xen-devel@lists.xenproject.org, Michal Hocko , Andrew Morton , "Michael S . Tsirkin" , Michal Hocko , Pankaj Gupta , Wei Yang , Baoquan He List-ID: On 30.04.20 17:38, Eric W. Biederman wrote: > David Hildenbrand writes: >=20 >> Some devices/drivers that add memory via add_memory() and friends (e.g., >> dax/kmem, but also virtio-mem in the future) don't want to create entrie= s >> in /sys/firmware/memmap/ - primarily to hinder kexec from adding this >> memory to the boot memmap of the kexec kernel. >> >> In fact, such memory is never exposed via the firmware memmap as System >> RAM (e.g., e820), so exposing this memory via /sys/firmware/memmap/ is >> wrong: >> "kexec needs the raw firmware-provided memory map to setup the >> parameter segment of the kernel that should be booted with >> kexec. Also, the raw memory map is useful for debugging. For >> that reason, /sys/firmware/memmap is an interface that provides >> the raw memory map to userspace." [1] >> >> We don't have to worry about firmware_map_remove() on the removal path. >> If there is no entry, it will simply return with -EINVAL. >> >> [1] >> https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-firmware-memm= ap >=20 >=20 > You know what this justification is rubbish, and I have previously > explained why it is rubbish. Actually, no, I don't think it is rubbish. See patch #3 and the cover letter why this is the right thing to do *for special memory*, *not ordinary DIMMs*. And to be quite honest, I think your response is a little harsh. I don't recall you replying to my virtio-mem-related comments. >=20 > Nacked-by: "Eric W. Biederman" >=20 > This needs to be based on weather the added memory is ultimately normal > ram or is something special. Yes, that's what the caller are expected to decide, see patch #3. kexec should try to be as closely as possible to a real reboot - IMHO. >=20 > At least when we are talking memory resources. Keeping it out of the > firmware map that is fine. >=20 > If the hotplugged memory is the result of plugging a stick of ram > into the kernel and can and should used be like any other memory > it should be treated like any normal memory. >=20 > If the hotplugged memory is something special it should be treated as > something special. I am really sorry, I can't make sense of what you are trying to say here. >=20 > Justifying behavior by documentation that does not consider memory > hotplug is bad thinking. Are you maybe confusing this patch series with the arm64 approach? This is not about ordinary hotplugged DIMMs. I'd love to get Dan's, Dave's and Michal's opinion. --=20 Thanks, David / dhildenb --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org