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Tue, 7 May 2019 19:21:57 +0000 (UTC) Subject: Re: [PATCH v2 0/8] mm/memory_hotplug: Factor out memory block device handling To: Dan Williams References: <20190507183804.5512-1-david@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: <6f69e615-2b4a-ff31-5d2a-e1711c564f9b@redhat.com> Date: Tue, 7 May 2019 21:21:56 +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: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.49]); Tue, 07 May 2019 19:22:09 +0000 (UTC) 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: Oscar Salvador , Michal Hocko , linux-ia64@vger.kernel.org, Linux-sh , Peter Zijlstra , Dave Hansen , Heiko Carstens , Chris Wilson , Linux MM , Pavel Tatashin , Rich Felker , Arun KS , "H. Peter Anvin" , Ingo Molnar , Qian Cai , linux-s390 , Baoquan He , Logan Gunthorpe , "Rafael J. Wysocki" , Mike Rapoport , "mike.travis@hpe.com" , Ingo Molnar , Fenghua Yu , Pavel Tatashin , Vasily Gorbik , Rob Herring , Masahiro Yamada , Nicholas Piggin , Martin Schwidefsky , Mark Brown , Borislav Petkov , Andy Lutomirski , Jonathan Cameron , Thomas Gleixner , Wei Yang , Joonsoo Kim , Oscar Salvador , Tony Luck , Yoshinori Sato , Andrew Banman , Mathieu Malaterre , Greg Kroah-Hartman , Linux Kernel Mailing List , Mike Rapoport , Wei Yang , Alex Deucher , Paul Mackerras , Andrew Morton , linuxppc-dev , "David S. Miller" , "Kirill A. Shutemov" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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? -- Thanks, David / dhildenb