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=-8.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, 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 87542C83004 for ; Wed, 29 Apr 2020 14:55:50 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4C90C206F0 for ; Wed, 29 Apr 2020 14:55:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="aaQ6Xiw1" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4C90C206F0 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id DDDA78E0007; Wed, 29 Apr 2020 10:55:49 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D8ED68E0005; Wed, 29 Apr 2020 10:55:49 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C7D458E0007; Wed, 29 Apr 2020 10:55:49 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0112.hostedemail.com [216.40.44.112]) by kanga.kvack.org (Postfix) with ESMTP id AE2258E0005 for ; Wed, 29 Apr 2020 10:55:49 -0400 (EDT) Received: from smtpin13.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 6CCB1181AC9CB for ; Wed, 29 Apr 2020 14:55:49 +0000 (UTC) X-FDA: 76761192018.13.bath91_15aab27416703 X-HE-Tag: bath91_15aab27416703 X-Filterd-Recvd-Size: 9363 Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [207.211.31.120]) by imf49.hostedemail.com (Postfix) with ESMTP for ; Wed, 29 Apr 2020 14:55:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588172148; 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=cmhYDjx7R1ZKenhsmfOQq46IgFNLN7K7NV7wFRLDEzo=; b=aaQ6Xiw1ntYEhF7JgSjH8iQQpAi+dKFD1S6Om48/fAvOYQRcTD/yYpqldNaMrSlyEMSffZ woDrvTtZHTL+iFVDyR23A6750JoYpujLYw43Nq25nx35kWSXhRJROQ+GbFowfMOTcX094W hbMyjc4kjBWsZr/HJOWEpvuNTJti5nI= 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-413-OwJjmeQjPQiHe7jQlfbisQ-1; Wed, 29 Apr 2020 10:55:44 -0400 X-MC-Unique: OwJjmeQjPQiHe7jQlfbisQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6CA921005510; Wed, 29 Apr 2020 14:55:41 +0000 (UTC) Received: from [10.36.114.55] (ovpn-114-55.ams2.redhat.com [10.36.114.55]) by smtp.corp.redhat.com (Postfix) with ESMTP id 237A460D3D; Wed, 29 Apr 2020 14:55:38 +0000 (UTC) Subject: Re: [PATCH v2] s390: simplify memory notifier for protecting kdump crash kernel area To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linux-s390@vger.kernel.org, Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Martin Schwidefsky , Philipp Rudo , Gerald Schaefer , "Eric W . Biederman" , Michal Hocko References: <20200424083904.8587-1-david@redhat.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: <1d79310d-8909-73e7-d2dd-90e8b9edf253@redhat.com> Date: Wed, 29 Apr 2020 16:55:38 +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: <20200424083904.8587-1-david@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 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 24.04.20 10:39, David Hildenbrand wrote: > Assume we have a crashkernel area of 256MB reserved: > > root@vm0:~# cat /proc/iomem > 00000000-6fffffff : System RAM > 0f258000-0fcfffff : Kernel code > 0fd00000-101d10e3 : Kernel data > 105b3000-1068dfff : Kernel bss > 70000000-7fffffff : Crash kernel > > This exactly corresponds to memory block 7 (memory block size is 256MB). > Trying to offline that memory block results in: > > root@vm0:~# echo "offline" > /sys/devices/system/memory/memory7/state > -bash: echo: write error: Device or resource busy > > [ 128.458762] page:000003d081c00000 refcount:1 mapcount:0 mapping:00000000d01cecd4 index:0x0 > [ 128.458773] flags: 0x1ffff00000001000(reserved) > [ 128.458781] raw: 1ffff00000001000 000003d081c00008 000003d081c00008 0000000000000000 > [ 128.458781] raw: 0000000000000000 0000000000000000 ffffffff00000001 0000000000000000 > [ 128.458783] page dumped because: unmovable page > > The craskernel area is marked reserved in the bootmem allocator. This > results in the memmap getting initialized (refcount=1, PG_reserved), but > the pages are never freed to the page allocator. > > So these pages look like allocated pages that are unmovable (esp. > PG_reserved), and therefore, memory offlining fails early, when trying to > isolate the page range. > > We only have to care about the exchange area, make that clear. > > Cc: Heiko Carstens > Cc: Vasily Gorbik > Cc: Christian Borntraeger > Cc: Martin Schwidefsky > Cc: Philipp Rudo > Cc: Gerald Schaefer > Cc: Eric W. Biederman > Cc: Michal Hocko > Signed-off-by: David Hildenbrand > --- > > Follow up of: > - "[PATCH v1] s390: drop memory notifier for protecting kdump crash kernel > area" > > v1 -> v2: > - Keep the notifier, check for exchange area only > > --- > arch/s390/kernel/setup.c | 13 +++++-------- > 1 file changed, 5 insertions(+), 8 deletions(-) > > diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c > index 0f0b140b5558..c0881f0a3175 100644 > --- a/arch/s390/kernel/setup.c > +++ b/arch/s390/kernel/setup.c > @@ -594,9 +594,10 @@ static void __init setup_memory_end(void) > #ifdef CONFIG_CRASH_DUMP > > /* > - * When kdump is enabled, we have to ensure that no memory from > - * the area [0 - crashkernel memory size] and > - * [crashk_res.start - crashk_res.end] is set offline. > + * When kdump is enabled, we have to ensure that no memory from the area > + * [0 - crashkernel memory size] is set offline - it will be exchanged with > + * the crashkernel memory region when kdump is triggered. The crashkernel > + * memory region can never get offlined (pages are unmovable). > */ > static int kdump_mem_notifier(struct notifier_block *nb, > unsigned long action, void *data) > @@ -607,11 +608,7 @@ static int kdump_mem_notifier(struct notifier_block *nb, > return NOTIFY_OK; > if (arg->start_pfn < PFN_DOWN(resource_size(&crashk_res))) > return NOTIFY_BAD; > - if (arg->start_pfn > PFN_DOWN(crashk_res.end)) > - return NOTIFY_OK; > - if (arg->start_pfn + arg->nr_pages - 1 < PFN_DOWN(crashk_res.start)) > - return NOTIFY_OK; > - return NOTIFY_BAD; > + return NOTIFY_OK; > } > > static struct notifier_block kdump_mem_nb = { > Ping. -- Thanks, David / dhildenb