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(p200300d82f16e400525adf911f90a6a8.dip0.t-ipconnect.de. [2003:d8:2f16:e400:525a:df91:1f90:a6a8]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-447f74cce5bsm21632555e9.24.2025.05.20.01.58.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 20 May 2025 01:58:13 -0700 (PDT) Message-ID: <43ab8a08-b577-4e6d-8920-1761ffbc01fc@redhat.com> Date: Tue, 20 May 2025 10:58:11 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 0/4] Make MIGRATE_ISOLATE a standalone bit To: Zi Yan Cc: Vlastimil Babka , Oscar Salvador , Johannes Weiner , linux-mm@kvack.org, Andrew Morton , Baolin Wang , "Kirill A . Shutemov" , Mel Gorman , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Richard Chang , linux-kernel@vger.kernel.org References: <20250509200111.3372279-1-ziy@nvidia.com> <794d741f-44ac-4cd8-97e8-091f12387f39@redhat.com> <0A1FA061-9E8E-4E86-A479-EFA9FF083D4F@nvidia.com> From: David Hildenbrand Content-Language: en-US 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: <0A1FA061-9E8E-4E86-A479-EFA9FF083D4F@nvidia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 19.05.25 16:35, Zi Yan wrote: > On 19 May 2025, at 10:15, David Hildenbrand wrote: > >> On 18.05.25 02:20, Zi Yan wrote: >>> On 17 May 2025, at 16:26, Vlastimil Babka wrote: >>> >>>> On 5/9/25 22:01, Zi Yan wrote: >>>>> Hi David and Oscar, >>>>> >>>>> Can you take a look at Patch 2, which changes how online_pages() set >>>>> online pageblock migratetypes? It used to first set all pageblocks to >>>>> MIGRATE_ISOLATE, then let undo_isolate_page_range() move the pageblocks >>>>> to MIGRATE_MOVABLE. After MIGRATE_ISOLATE becomes a standalone bit, all >>>>> online pageblocks need to have a migratetype other than MIGRATE_ISOLATE. >>>>> Let me know if there is any issue with my changes. >>>>> >>>>> Hi Johannes, >>>>> >>>>> Patch 2 now have set_pageblock_migratetype() not accepting >>>>> MIGRATE_ISOLATE. I think it makes code better. Thank you for the great >>>>> feedback. >>>>> >>>>> Hi all, >>>>> >>>>> This patchset moves MIGRATE_ISOLATE to a standalone bit to avoid >>>>> being overwritten during pageblock isolation process. Currently, >>>>> MIGRATE_ISOLATE is part of enum migratetype (in include/linux/mmzone.h), >>>>> thus, setting a pageblock to MIGRATE_ISOLATE overwrites its original >>>>> migratetype. This causes pageblock migratetype loss during >>>>> alloc_contig_range() and memory offline, especially when the process >>>>> fails due to a failed pageblock isolation and the code tries to undo the >>>>> finished pageblock isolations. >>>> >>>> Seems mostly fine to me, just sent suggestion for 4/4. >>> >>> Thanks. >>> >>>> I was kinda hoping that MIGRATE_ISOLATE could stop being a migratetype. But >>>> I also see that it's useful for it to be because then it means it has the >>>> freelists in the buddy allocator, can work via __move_freepages_block() etc. >>> >>> Yeah, I wanted to remove MIGRATE_ISOLATE from migratetype too, but there >>> is a MIGRATE_ISOLATE freelist and /proc/pagetypeinfo also shows isolated >>> free pages. >> >> The latter, we can likely fake. >> >> Is there a reasonable way to remove MIGRATE_ISOLATE completely? >> >> Of course, we could simply duplicate the page lists (one set for isolated, one set for !isolated), or keep it as is and simply have a > > That could work. It will change vmcore layout and I wonder if that is a concern > or not. Not really. makedumpfile will have to implement support for the new layout as it adds support for the new kernel version. > >> separate one that we separate out. So, we could have a migratetype+isolated pair instead. > > What do you mean by a migratetype+isolate pair? If MIGRATE_ISOLATE no longer exists, relevant code would have to pass migratetype+isolated (essentially, what you did in init_pageblock_migratetype ). E.g., we could pass around a "pageblock_info" (or however we call it, using a different type than a bare migratetype) from which we can easily extract the migratetype and the isolated state. E.g., init_pageblock_migratetype() could then become struct pageblock_info pb_info = { .migratetype = MIGRATE_MOVABLE, .isolated = true, } init_pageblock_info(page, pb_info); So, we'd decouple the migratetype we pass around from the "isolated" state. Whoever needs the "isolated" state in addition to the migratetype should use get_pageblock_info(). When adding to lists, we can decide what to do based on that information. > >> >> Just a thought, did not look into all the ugly details. > > Another thought is that maybe caller should keep the isolated free pages instead > to make it actually isolated. You mean, not adding them to a list at all in the buddy? I think the problem is that if a page gets freed while the pageblock is isolated, it cannot get added to the list of an owner easily. -- Cheers, David / dhildenb