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,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 CB8B4C18E5B for ; Mon, 16 Mar 2020 15:49:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 891BD20679 for ; Mon, 16 Mar 2020 15:49:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="HB8VYvhh" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731979AbgCPPtE (ORCPT ); Mon, 16 Mar 2020 11:49:04 -0400 Received: from us-smtp-delivery-74.mimecast.com ([63.128.21.74]:21997 "EHLO us-smtp-delivery-74.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731868AbgCPPtD (ORCPT ); Mon, 16 Mar 2020 11:49:03 -0400 X-Greylist: delayed 1912 seconds by postgrey-1.27 at vger.kernel.org; Mon, 16 Mar 2020 11:49:02 EDT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1584373742; 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=aJCci1JpnVafZT1pCNJDWw/c8ajwNjmH5zsDBnK+wN4=; b=HB8VYvhhKSBZQDZTgRsBLlN6cgdYp8lXzvulhywykeYT+PMB/4KfpDWlnNpHhgYgAGmZ+d hUxY4Y7fWzIy0JNNeaXGpzGFrYHp40iq+rdna9U5VrEQiUfxBMV05zFG96uGBLZEFz7T4m 7d6BrPUtFkiqlh7LD9IZarvnOJxV18o= 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-42-K1fzh2o9PiCg1bNXJzv67w-1; Mon, 16 Mar 2020 11:48:56 -0400 X-MC-Unique: K1fzh2o9PiCg1bNXJzv67w-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 7BEFB1196B20; Mon, 16 Mar 2020 15:48:39 +0000 (UTC) Received: from [10.36.118.207] (ovpn-118-207.ams2.redhat.com [10.36.118.207]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4216E5DA7B; Mon, 16 Mar 2020 15:48:37 +0000 (UTC) Subject: Re: [PATCH v1 5/5] mm/memory_hotplug: allow to specify a default online_type To: Michal Hocko Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-hyperv@vger.kernel.org, Greg Kroah-Hartman , Andrew Morton , Oscar Salvador , "Rafael J. Wysocki" , Baoquan He , Wei Yang References: <20200311123026.16071-1-david@redhat.com> <20200311123026.16071-6-david@redhat.com> <20200316153131.GW11482@dhcp22.suse.cz> 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: <5ed312d3-bc2d-38da-166e-452ae3df9e81@redhat.com> Date: Mon, 16 Mar 2020 16:48:36 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200316153131.GW11482@dhcp22.suse.cz> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 16.03.20 16:31, Michal Hocko wrote: > On Wed 11-03-20 13:30:26, David Hildenbrand wrote: >> For now, distributions implement advanced udev rules to essentially >> - Don't online any hotplugged memory (s390x) >> - Online all memory to ZONE_NORMAL (e.g., most virt environments like >> hyperv) >> - Online all memory to ZONE_MOVABLE in case the zone imbalance is take= n >> care of (e.g., bare metal, special virt environments) >> >> In summary: All memory is usually onlined the same way, however, the >> kernel always has to ask userspace to come up with the same answer. >> E.g., HyperV always waits for a memory block to get onlined before >> continuing, otherwise it might end up adding memory faster than >> hotplugging it, which can result in strange OOM situations. >> >> Let's allow to specify a default online_type, not just "online" and >> "offline". This allows distributions to configure the default online_t= ype >> when booting up and be done with it. >> >> We can now specify "offline", "online", "online_movable" and >> "online_kernel" via >> - "memhp_default_state=3D" on the kernel cmdline >> - /sys/devices/systemn/memory/auto_online_blocks >> just like we are able to specify for a single memory block via >> /sys/devices/systemn/memory/memoryX/state >=20 > I still strongly believe that the whole interface is wrong. This is jus= t > adding more lipstick on the pig. On the other hand I recognize that the > event based onlining is a PITA as well. The proper interface would > somehow communicate the type of the memory via the event or other sysfs > attribute and then the FW/HV could tell that this is an offline memory, > hotplugable memory or just an additional memory that doesn't need to > support hotremove by the consumer. The userspace or the kernel could > handle the hotadd request much more easier that way. Yeah, and I proposed patches like that which were not well received [1] [= 2]. But then, user space usually wants to online all memory the same way right now. Also, HyperV and virtio-mem don't want to wait for onlining to happen in user space, because it slows down the whole "add a hole bunch of memory" process. >=20 >> Cc: Greg Kroah-Hartman >> Cc: Andrew Morton >> Cc: Michal Hocko >> Cc: Oscar Salvador >> Cc: "Rafael J. Wysocki" >> Cc: Baoquan He >> Cc: Wei Yang >> Signed-off-by: David Hildenbrand >=20 > That being said, I will not object to this patch. I simply gave up > fighting this interface. So if it works for consumers and it doesn't > break the existing userspace (which is shouldn't AFAICS) then go ahead. As it solves a real problem and makes the interface to auto online usable, I don't think anything speaks against it. Thanks! [1] https://spinics.net/lists/linux-driver-devel/msg118337.html [2] https://www.mail-archive.com/xen-devel@lists.xenproject.org/msg32420.html --=20 Thanks, David / dhildenb