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[2003:cb:c73c:f800:7df6:a2c9:652e:c799]) by smtp.gmail.com with ESMTPSA id m11-20020a05600c4f4b00b0040651505684sm8840526wmq.29.2023.10.30.03.20.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 30 Oct 2023 03:20:22 -0700 (PDT) Message-ID: <4df63333-de57-4a58-a110-77b4fdfa6a9e@redhat.com> Date: Mon, 30 Oct 2023 11:20:21 +0100 Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7 2/3] mm/memory_hotplug: split memmap_on_memory requests across memblocks To: Vishal Verma , Andrew Morton , Oscar Salvador , Dan Williams , Dave Jiang Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, Huang Ying , Dave Hansen , "Aneesh Kumar K.V" , Michal Hocko , Jonathan Cameron , Jeff Moyer References: <20231025-vv-kmem_memmap-v7-0-4a76d7652df5@intel.com> <20231025-vv-kmem_memmap-v7-2-4a76d7652df5@intel.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; 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 ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz 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+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: <20231025-vv-kmem_memmap-v7-2-4a76d7652df5@intel.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 26.10.23 00:44, Vishal Verma wrote: > The MHP_MEMMAP_ON_MEMORY flag for hotplugged memory is restricted to > 'memblock_size' chunks of memory being added. Adding a larger span of > memory precludes memmap_on_memory semantics. > > For users of hotplug such as kmem, large amounts of memory might get > added from the CXL subsystem. In some cases, this amount may exceed the > available 'main memory' to store the memmap for the memory being added. > In this case, it is useful to have a way to place the memmap on the > memory being added, even if it means splitting the addition into > memblock-sized chunks. > > Change add_memory_resource() to loop over memblock-sized chunks of > memory if caller requested memmap_on_memory, and if other conditions for > it are met. Teach try_remove_memory() to also expect that a memory > range being removed might have been split up into memblock sized chunks, > and to loop through those as needed. > > This does preclude being able to use PUD mappings in the direct map; a > proposal to how this could be optimized in the future is laid out > here[1]. Almost there, I think :) > > +static int create_altmaps_and_memory_blocks(int nid, struct memory_group *group, > + u64 start, u64 size) > +{ > + unsigned long memblock_size = memory_block_size_bytes(); > + u64 cur_start; > + int ret; > + > + for (cur_start = start; cur_start < start + size; > + cur_start += memblock_size) { > + struct mhp_params params = { .pgprot = > + pgprot_mhp(PAGE_KERNEL) }; > + struct vmem_altmap mhp_altmap = { > + .base_pfn = PHYS_PFN(cur_start), > + .end_pfn = PHYS_PFN(cur_start + memblock_size - 1), > + }; > + > + mhp_altmap.free = memory_block_memmap_on_memory_pages(); > + params.altmap = kmemdup(&mhp_altmap, sizeof(struct vmem_altmap), > + GFP_KERNEL); > + if (!params.altmap) > + return -ENOMEM; Best to cleanup here instead of handling it in the caller [as noted by Vishal, we might not be doing that yet]. Using remove_memory_blocks_and_altmaps() on the fully processed range sounds reasonable. maybe something like ret = arch_add_memory(nid, cur_start, memblock_size, ¶ms); if (ret) { kfree(params.altmap); goto out; } ret = create_memory_block_devices(cur_start, memblock_size, params.altmap, group); if (ret) { arch_remove_memory(cur_start, memblock_size, NULL); kfree(params.altmap); goto out; } if (ret && cur_start != start) remove_memory_blocks_and_altmaps(start, cur_start - start); return ret; > + > + /* call arch's memory hotadd */ > + ret = arch_add_memory(nid, cur_start, memblock_size, ¶ms); > + if (ret < 0) { > + kfree(params.altmap); > + return ret; > + } > + > + /* create memory block devices after memory was added */ > + ret = create_memory_block_devices(cur_start, memblock_size, > + params.altmap, group); > + if (ret) { > + arch_remove_memory(cur_start, memblock_size, NULL); > + kfree(params.altmap); > + return ret; > + } > + } > + > + return 0; > +} > + [...] > static int check_cpu_on_node(int nid) > { > int cpu; > @@ -2146,11 +2186,69 @@ void try_offline_node(int nid) > } > EXPORT_SYMBOL(try_offline_node); > > -static int __ref try_remove_memory(u64 start, u64 size) > +static void __ref remove_memory_blocks_and_altmaps(u64 start, u64 size) > { > - struct memory_block *mem; > - int rc = 0, nid = NUMA_NO_NODE; > + unsigned long memblock_size = memory_block_size_bytes(); > struct vmem_altmap *altmap = NULL; > + struct memory_block *mem; > + u64 cur_start; > + int rc; > + > + /* > + * For memmap_on_memory, the altmaps could have been added on > + * a per-memblock basis. Loop through the entire range if so, > + * and remove each memblock and its altmap. > + */ /* * altmaps where added on a per-memblock basis; we have to process * each individual memory block. */ > + for (cur_start = start; cur_start < start + size; > + cur_start += memblock_size) { > + rc = walk_memory_blocks(cur_start, memblock_size, &mem, > + test_has_altmap_cb); > + if (rc) { > + altmap = mem->altmap; > + /* > + * Mark altmap NULL so that we can add a debug > + * check on memblock free. > + */ > + mem->altmap = NULL; > + } Simpler (especially, we know that there must be an altmap): mem = find_memory_block(pfn_to_section_nr(cur_start)); altmap = mem->altmap; mem->altmap = NULL; I think we might be able to remove test_has_altmap_cb() then. > + > + remove_memory_block_devices(cur_start, memblock_size); > + > + arch_remove_memory(cur_start, memblock_size, altmap); > + > + /* Verify that all vmemmap pages have actually been freed. */ > + if (altmap) { There must be an altmap, so this can be done unconditionally. > + WARN(altmap->alloc, "Altmap not fully unmapped"); > + kfree(altmap); > + } > + } > +} -- Cheers, David / dhildenb