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=-6.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 34C96C004C9 for ; Tue, 7 May 2019 21:13:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F0D0420825 for ; Tue, 7 May 2019 21:13:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728490AbfEGVN2 (ORCPT ); Tue, 7 May 2019 17:13:28 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37038 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726686AbfEGVN1 (ORCPT ); Tue, 7 May 2019 17:13:27 -0400 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 mx1.redhat.com (Postfix) with ESMTPS id 866CA300271F; Tue, 7 May 2019 21:13:26 +0000 (UTC) Received: from [10.36.116.95] (ovpn-116-95.ams2.redhat.com [10.36.116.95]) by smtp.corp.redhat.com (Postfix) with ESMTP id CF61E60139; Tue, 7 May 2019 21:13:23 +0000 (UTC) Subject: Re: [PATCH v2 2/8] s390x/mm: Implement arch_remove_memory() To: Dan Williams Cc: Linux MM , Linux Kernel Mailing List , linux-ia64@vger.kernel.org, linuxppc-dev , linux-s390 , Linux-sh , Andrew Morton , Martin Schwidefsky , Heiko Carstens , Michal Hocko , Mike Rapoport , Vasily Gorbik , Oscar Salvador References: <20190507183804.5512-1-david@redhat.com> <20190507183804.5512-3-david@redhat.com> <97a6a2ab-0e8b-d403-ca39-ffa4425e15a5@redhat.com> From: David Hildenbrand Openpgp: preference=signencrypt Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= xsFNBFXLn5EBEAC+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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwX4EEwECACgFAljj9eoCGwMFCQlmAYAGCwkI BwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEE3eEPcA/4Na5IIP/3T/FIQMxIfNzZshIq687qgG 8UbspuE/YSUDdv7r5szYTK6KPTlqN8NAcSfheywbuYD9A4ZeSBWD3/NAVUdrCaRP2IvFyELj xoMvfJccbq45BxzgEspg/bVahNbyuBpLBVjVWwRtFCUEXkyazksSv8pdTMAs9IucChvFmmq3 jJ2vlaz9lYt/lxN246fIVceckPMiUveimngvXZw21VOAhfQ+/sofXF8JCFv2mFcBDoa7eYob s0FLpmqFaeNRHAlzMWgSsP80qx5nWWEvRLdKWi533N2vC/EyunN3HcBwVrXH4hxRBMco3jvM m8VKLKao9wKj82qSivUnkPIwsAGNPdFoPbgghCQiBjBe6A75Z2xHFrzo7t1jg7nQfIyNC7ez MZBJ59sqA9EDMEJPlLNIeJmqslXPjmMFnE7Mby/+335WJYDulsRybN+W5rLT5aMvhC6x6POK z55fMNKrMASCzBJum2Fwjf/VnuGRYkhKCqqZ8gJ3OvmR50tInDV2jZ1DQgc3i550T5JDpToh dPBxZocIhzg+MBSRDXcJmHOx/7nQm3iQ6iLuwmXsRC6f5FbFefk9EjuTKcLMvBsEx+2DEx0E UnmJ4hVg7u1PQ+2Oy+Lh/opK/BDiqlQ8Pz2jiXv5xkECvr/3Sv59hlOCZMOaiLTTjtOIU7Tq 7ut6OL64oAq+zsFNBFXLn5EBEADn1959INH2cwYJv0tsxf5MUCghCj/CA/lc/LMthqQ773ga uB9mN+F1rE9cyyXb6jyOGn+GUjMbnq1o121Vm0+neKHUCBtHyseBfDXHA6m4B3mUTWo13nid 0e4AM71r0DS8+KYh6zvweLX/LL5kQS9GQeT+QNroXcC1NzWbitts6TZ+IrPOwT1hfB4WNC+X 2n4AzDqp3+ILiVST2DT4VBc11Gz6jijpC/KI5Al8ZDhRwG47LUiuQmt3yqrmN63V9wzaPhC+ xbwIsNZlLUvuRnmBPkTJwwrFRZvwu5GPHNndBjVpAfaSTOfppyKBTccu2AXJXWAE1Xjh6GOC 8mlFjZwLxWFqdPHR1n2aPVgoiTLk34LR/bXO+e0GpzFXT7enwyvFFFyAS0Nk1q/7EChPcbRb hJqEBpRNZemxmg55zC3GLvgLKd5A09MOM2BrMea+l0FUR+PuTenh2YmnmLRTro6eZ/qYwWkC u8FFIw4pT0OUDMyLgi+GI1aMpVogTZJ70FgV0pUAlpmrzk/bLbRkF3TwgucpyPtcpmQtTkWS gDS50QG9DR/1As3LLLcNkwJBZzBG6PWbvcOyrwMQUF1nl4SSPV0LLH63+BrrHasfJzxKXzqg rW28CTAE2x8qi7e/6M/+XXhrsMYG+uaViM7n2je3qKe7ofum3s4vq7oFCPsOgwARAQABwsFl BBgBAgAPBQJVy5+RAhsMBQkJZgGAAAoJEE3eEPcA/4NagOsP/jPoIBb/iXVbM+fmSHOjEshl KMwEl/m5iLj3iHnHPVLBUWrXPdS7iQijJA/VLxjnFknhaS60hkUNWexDMxVVP/6lbOrs4bDZ NEWDMktAeqJaFtxackPszlcpRVkAs6Msn9tu8hlvB517pyUgvuD7ZS9gGOMmYwFQDyytpepo YApVV00P0u3AaE0Cj/o71STqGJKZxcVhPaZ+LR+UCBZOyKfEyq+ZN311VpOJZ1IvTExf+S/5 lqnciDtbO3I4Wq0ArLX1gs1q1XlXLaVaA3yVqeC8E7kOchDNinD3hJS4OX0e1gdsx/e6COvy qNg5aL5n0Kl4fcVqM0LdIhsubVs4eiNCa5XMSYpXmVi3HAuFyg9dN+x8thSwI836FoMASwOl C7tHsTjnSGufB+D7F7ZBT61BffNBBIm1KdMxcxqLUVXpBQHHlGkbwI+3Ye+nE6HmZH7IwLwV W+Ajl7oYF+jeKaH4DZFtgLYGLtZ1LDwKPjX7VAsa4Yx7S5+EBAaZGxK510MjIx6SGrZWBrrV TEvdV00F2MnQoeXKzD7O4WFbL55hhyGgfWTHwZ457iN9SgYi1JLPqWkZB0JRXIEtjd4JEQcx +8Umfre0Xt4713VxMygW0PnQt5aSQdMD58jHFxTk092mU+yIHj5LeYgvwSgZN4airXk5yRXl SE+xAvmumFBY Organization: Red Hat GmbH Message-ID: <942f4952-b8bf-86fb-fd10-4fd5519198aa@redhat.com> Date: Tue, 7 May 2019 23:13:22 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Tue, 07 May 2019 21:13:26 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07.05.19 22:57, Dan Williams wrote: > On Tue, May 7, 2019 at 1:47 PM David Hildenbrand wrote: >> >> On 07.05.19 22:46, Dan Williams wrote: >>> On Tue, May 7, 2019 at 11:38 AM David Hildenbrand wrote: >>>> >>>> Will come in handy when wanting to handle errors after >>>> arch_add_memory(). >>>> >>>> Cc: Martin Schwidefsky >>>> Cc: Heiko Carstens >>>> Cc: Andrew Morton >>>> Cc: Michal Hocko >>>> Cc: Mike Rapoport >>>> Cc: David Hildenbrand >>>> Cc: Vasily Gorbik >>>> Cc: Oscar Salvador >>>> Signed-off-by: David Hildenbrand >>>> --- >>>> arch/s390/mm/init.c | 13 +++++++------ >>>> 1 file changed, 7 insertions(+), 6 deletions(-) >>>> >>>> diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c >>>> index 31b1071315d7..1e0cbae69f12 100644 >>>> --- a/arch/s390/mm/init.c >>>> +++ b/arch/s390/mm/init.c >>>> @@ -237,12 +237,13 @@ int arch_add_memory(int nid, u64 start, u64 size, >>>> void arch_remove_memory(int nid, u64 start, u64 size, >>>> struct vmem_altmap *altmap) >>>> { >>>> - /* >>>> - * There is no hardware or firmware interface which could trigger a >>>> - * hot memory remove on s390. So there is nothing that needs to be >>>> - * implemented. >>>> - */ >>>> - BUG(); >>>> + unsigned long start_pfn = start >> PAGE_SHIFT; >>>> + unsigned long nr_pages = size >> PAGE_SHIFT; >>>> + struct zone *zone; >>>> + >>>> + zone = page_zone(pfn_to_page(start_pfn)); >>> >>> Does s390 actually support passing in an altmap? If 'yes', I think it >>> also needs the vmem_altmap_offset() fixup like x86-64: >>> >>> /* With altmap the first mapped page is offset from @start */ >>> if (altmap) >>> page += vmem_altmap_offset(altmap); >>> >>> ...but I suspect it does not support altmap since >>> arch/s390/mm/vmem.c::vmemmap_populate() does not arrange for 'struct >>> page' capacity to be allocated out of an altmap defined page pool. >>> >>> I think it would be enough to disallow any arch_add_memory() on s390 >>> where @altmap is non-NULL. At least until s390 gains ZONE_DEVICE >>> support and can enable the pmem use case. >>> >> >> As far as I know, it doesn't yet, however I guess this could change once >> virtio-pmem is supported? > > I would expect and request virtio-pmem remain a non-starter on s390 > until s390 gains ZONE_DEVICE support. As it stands virtio-pmem is just > another flavor of the general pmem driver and the pmem driver > currently only exports ZONE_DEVICE pfns tagged by the PTE_DEVMAP > pte-flag and PFN_DEV+PFN_MAP pfn_t-flags. Yes, I think ZONE_DEVICE will be the way to go. On real HW, there will never be anything mapped into the physical address space besides system ram. However with virtio-pmem in virtual environments, we have the option to change that. -- Thanks, David / dhildenb