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Wed, 5 Jun 2019 21:50:53 +0000 (UTC) Subject: Re: [PATCH v3 07/11] mm/memory_hotplug: Create memory block devices after arch_add_memory() To: Wei Yang References: <20190527111152.16324-1-david@redhat.com> <20190527111152.16324-8-david@redhat.com> <20190604214234.ltwtkcdoju2gxisx@master> <9a1d282f-8dd9-a48b-cc96-f9afaa435c62@redhat.com> <20190605212249.s7knac6vimealdmx@master> 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: <4d29c1d6-d394-903d-28ae-733d55ac06f4@redhat.com> Date: Wed, 5 Jun 2019 23:50:52 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20190605212249.s7knac6vimealdmx@master> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.49]); Wed, 05 Jun 2019 21:50:58 +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: linux-s390@vger.kernel.org, Michal Hocko , linux-ia64@vger.kernel.org, Pavel Tatashin , linux-sh@vger.kernel.org, "mike.travis@hpe.com" , Greg Kroah-Hartman , "Rafael J. Wysocki" , Mathieu Malaterre , linux-kernel@vger.kernel.org, Arun KS , Ingo Molnar , linux-mm@kvack.org, Andrew Banman , Qian Cai , Igor Mammedov , akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org, Dan Williams , linux-arm-kernel@lists.infradead.org, Oscar Salvador Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 05.06.19 23:22, Wei Yang wrote: > On Wed, Jun 05, 2019 at 12:58:46PM +0200, David Hildenbrand wrote: >> On 05.06.19 10:58, David Hildenbrand wrote: >>>>> /* >>>>> * For now, we have a linear search to go find the appropriate >>>>> * memory_block corresponding to a particular phys_index. If >>>>> @@ -658,6 +670,11 @@ static int init_memory_block(struct memory_block **memory, int block_id, >>>>> unsigned long start_pfn; >>>>> int ret = 0; >>>>> >>>>> + mem = find_memory_block_by_id(block_id, NULL); >>>>> + if (mem) { >>>>> + put_device(&mem->dev); >>>>> + return -EEXIST; >>>>> + } >>>> >>>> find_memory_block_by_id() is not that close to the main idea in this patch. >>>> Would it be better to split this part? >>> >>> I played with that but didn't like the temporary results (e.g. having to >>> export find_memory_block_by_id()). I'll stick to this for now. >>> >>>> >>>>> mem = kzalloc(sizeof(*mem), GFP_KERNEL); >>>>> if (!mem) >>>>> return -ENOMEM; >>>>> @@ -699,44 +716,53 @@ static int add_memory_block(int base_section_nr) >>>>> return 0; >>>>> } >>>>> >>>>> +static void unregister_memory(struct memory_block *memory) >>>>> +{ >>>>> + if (WARN_ON_ONCE(memory->dev.bus != &memory_subsys)) >>>>> + return; >>>>> + >>>>> + /* drop the ref. we got via find_memory_block() */ >>>>> + put_device(&memory->dev); >>>>> + device_unregister(&memory->dev); >>>>> +} >>>>> + >>>>> /* >>>>> - * need an interface for the VM to add new memory regions, >>>>> - * but without onlining it. >>>>> + * Create memory block devices for the given memory area. Start and size >>>>> + * have to be aligned to memory block granularity. Memory block devices >>>>> + * will be initialized as offline. >>>>> */ >>>>> -int hotplug_memory_register(int nid, struct mem_section *section) >>>>> +int create_memory_block_devices(unsigned long start, unsigned long size) >>>>> { >>>>> - int block_id = base_memory_block_id(__section_nr(section)); >>>>> - int ret = 0; >>>>> + const int start_block_id = pfn_to_block_id(PFN_DOWN(start)); >>>>> + int end_block_id = pfn_to_block_id(PFN_DOWN(start + size)); >>>>> struct memory_block *mem; >>>>> + unsigned long block_id; >>>>> + int ret = 0; >>>>> >>>>> - mutex_lock(&mem_sysfs_mutex); >>>>> + if (WARN_ON_ONCE(!IS_ALIGNED(start, memory_block_size_bytes()) || >>>>> + !IS_ALIGNED(size, memory_block_size_bytes()))) >>>>> + return -EINVAL; >>>>> >>>>> - mem = find_memory_block(section); >>>>> - if (mem) { >>>>> - mem->section_count++; >>>>> - put_device(&mem->dev); >>>>> - } else { >>>>> + mutex_lock(&mem_sysfs_mutex); >>>>> + for (block_id = start_block_id; block_id != end_block_id; block_id++) { >>>>> ret = init_memory_block(&mem, block_id, MEM_OFFLINE); >>>>> if (ret) >>>>> - goto out; >>>>> - mem->section_count++; >>>>> + break; >>>>> + mem->section_count = sections_per_block; >>>>> + } >>>>> + if (ret) { >>>>> + end_block_id = block_id; >>>>> + for (block_id = start_block_id; block_id != end_block_id; >>>>> + block_id++) { >>>>> + mem = find_memory_block_by_id(block_id, NULL); >>>>> + mem->section_count = 0; >>>>> + unregister_memory(mem); >>>>> + } >>>>> } >>>> >>>> Would it be better to do this in reverse order? >>>> >>>> And unregister_memory() would free mem, so it is still necessary to set >>>> section_count to 0? >>> >>> 1. I kept the existing behavior (setting it to 0) for now. I am planning >>> to eventually remove the section count completely (it could be >>> beneficial to detect removing of partially populated memory blocks). >> >> Correction: We already use it to block offlining of partially populated >> memory blocks \o/ > > Would you mind letting me know where we leverage this? Sure: drivers/base/memory.c:memory_subsys_offline() if (mem->section_count != sections_per_block) return -EINVAL; I would have expected such checks in the offline_pages() function instead. -- Thanks, David / dhildenb