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[209.132.183.28]) by mx.google.com with ESMTPS id a2si7791457qta.5.2019.05.07.12.38.00 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 07 May 2019 12:38:00 -0700 (PDT) Received-SPF: pass (google.com: domain of david@redhat.com designates 209.132.183.28 as permitted sender) client-ip=209.132.183.28; Authentication-Results: mx.google.com; spf=pass (google.com: domain of david@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 3689A309B151; Tue, 7 May 2019 19:37:58 +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 6230F6149F; Tue, 7 May 2019 19:37:46 +0000 (UTC) Subject: Re: [PATCH v2 0/8] mm/memory_hotplug: Factor out memory block device handling From: David Hildenbrand To: Dan Williams Cc: Linux MM , Linux Kernel Mailing List , linux-ia64@vger.kernel.org, linuxppc-dev , linux-s390 , Linux-sh , Andrew Morton , Alex Deucher , Andrew Banman , Andy Lutomirski , Arun KS , Baoquan He , Benjamin Herrenschmidt , Borislav Petkov , Christophe Leroy , Chris Wilson , Dave Hansen , "David S. Miller" , Fenghua Yu , Greg Kroah-Hartman , Heiko Carstens , "H. Peter Anvin" , Ingo Molnar , Ingo Molnar , Jonathan Cameron , Joonsoo Kim , "Kirill A. Shutemov" , Logan Gunthorpe , Mark Brown , Martin Schwidefsky , Masahiro Yamada , Mathieu Malaterre , Michael Ellerman , Michal Hocko , Mike Rapoport , Mike Rapoport , "mike.travis@hpe.com" , Nicholas Piggin , Oscar Salvador , Oscar Salvador , Paul Mackerras , Pavel Tatashin , Pavel Tatashin , Peter Zijlstra , Qian Cai , "Rafael J. Wysocki" , Rich Felker , Rob Herring , Thomas Gleixner , Tony Luck , Vasily Gorbik , Wei Yang , Wei Yang , Yoshinori Sato References: <20190507183804.5512-1-david@redhat.com> <6f69e615-2b4a-ff31-5d2a-e1711c564f9b@redhat.com> 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: Date: Tue, 7 May 2019 21:37:45 +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: <6f69e615-2b4a-ff31-5d2a-e1711c564f9b@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.49]); Tue, 07 May 2019 19:37:59 +0000 (UTC) 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 07.05.19 21:21, David Hildenbrand wrote: > On 07.05.19 21:04, Dan Williams wrote: >> On Tue, May 7, 2019 at 11:38 AM David Hildenbrand wrote: >>> >>> We only want memory block devices for memory to be onlined/offlined >>> (add/remove from the buddy). This is required so user space can >>> online/offline memory and kdump gets notified about newly onlined memory. >>> >>> Only such memory has the requirement of having to span whole memory blocks. >>> Let's factor out creation/removal of memory block devices. This helps >>> to further cleanup arch_add_memory/arch_remove_memory() and to make >>> implementation of new features easier. E.g. supplying a driver for >>> memory block devices becomes way easier (so user space is able to >>> distinguish different types of added memory to properly online it). >>> >>> Patch 1 makes sure the memory block size granularity is always respected. >>> Patch 2 implements arch_remove_memory() on s390x. Patch 3 prepares >>> arch_remove_memory() to be also called without CONFIG_MEMORY_HOTREMOVE. >>> Patch 4,5 and 6 factor out creation/removal of memory block devices. >>> Patch 7 gets rid of some unlikely errors that could have happened, not >>> removing links between memory block devices and nodes, previously brought >>> up by Oscar. >>> >>> Did a quick sanity test with DIMM plug/unplug, making sure all devices >>> and sysfs links properly get added/removed. Compile tested on s390x and >>> x86-64. >>> >>> Based on git://git.cmpxchg.org/linux-mmots.git >>> >>> Next refactoring on my list will be making sure that remove_memory() >>> will never deal with zones / access "struct pages". Any kind of zone >>> handling will have to be done when offlining system memory / before >>> removing device memory. I am thinking about remove_pfn_range_from_zone()", >>> du undo everything "move_pfn_range_to_zone()" did. >>> >>> v1 -> v2: >>> - s390x/mm: Implement arch_remove_memory() >>> -- remove mapping after "__remove_pages" >>> >>> >>> David Hildenbrand (8): >>> mm/memory_hotplug: Simplify and fix check_hotplug_memory_range() >>> s390x/mm: Implement arch_remove_memory() >>> mm/memory_hotplug: arch_remove_memory() and __remove_pages() with >>> CONFIG_MEMORY_HOTPLUG >>> mm/memory_hotplug: Create memory block devices after arch_add_memory() >>> mm/memory_hotplug: Drop MHP_MEMBLOCK_API >> >> So at a minimum we need a bit of patch staging guidance because this >> obviously collides with the subsection bits that are built on top of >> the existence of MHP_MEMBLOCK_API. What trigger do you envision as a >> replacement that arch_add_memory() use to determine that subsection >> operations should be disallowed? >> > > Looks like we now have time to sort it out :) > > > Looking at your series > > [PATCH v8 08/12] mm/sparsemem: Prepare for sub-section ranges > > is the "single" effectively place using MHP_MEMBLOCK_API, namely > "subsection_check()". Used when adding/removing memory. > > > +static int subsection_check(unsigned long pfn, unsigned long nr_pages, > + unsigned long flags, const char *reason) > +{ > + /* > + * Only allow partial section hotplug for !memblock ranges, > + * since register_new_memory() requires section alignment, and > + * CONFIG_SPARSEMEM_VMEMMAP=n requires sections to be fully > + * populated. > + */ > + if ((!IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP) > + || (flags & MHP_MEMBLOCK_API)) > + && ((pfn & ~PAGE_SECTION_MASK) > + || (nr_pages & ~PAGE_SECTION_MASK))) { > + WARN(1, "Sub-section hot-%s incompatible with %s\n", reason, > + (flags & MHP_MEMBLOCK_API) > + ? "memblock api" : "!CONFIG_SPARSEMEM_VMEMMAP"); > + return -EINVAL; > + } > + return 0; > } > > > (flags & MHP_MEMBLOCK_API)) && ((pfn & ~PAGE_SECTION_MASK) || (nr_pages > & ~PAGE_SECTION_MASK))) > > sounds like something the caller (add_memory()) always has to take care > of. No need to check. The one imposing this restriction is the only caller. > > In my opinion, that check/function can go completely. > > Am I missing something / missing another user? > In other word, this series moves the restriction out of arch_add_memory() and therefore you don't need subsection_check() at all anymore. At least if I am not missing something :) -- Thanks, David / dhildenb