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[2003:d8:2f1a:f500:4346:f17c:2bde:808c]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-454cd3d2661sm24623995e9.19.2025.07.08.07.38.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 08 Jul 2025 07:38:09 -0700 (PDT) Message-ID: Date: Tue, 8 Jul 2025 16:38:07 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC 08/11] mm/thp: add split during migration support To: Balbir Singh , linux-mm@kvack.org, akpm@linux-foundation.org Cc: dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org, Karol Herbst , Lyude Paul , Danilo Krummrich , David Airlie , Simona Vetter , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Shuah Khan , Barry Song , Baolin Wang , Ryan Roberts , Matthew Wilcox , Peter Xu , Zi Yan , Kefeng Wang , Jane Chu , Alistair Popple , Donet Tom References: <20250306044239.3874247-1-balbirs@nvidia.com> <20250306044239.3874247-9-balbirs@nvidia.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: <20250306044239.3874247-9-balbirs@nvidia.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: RdCNbnuYMld-oVxaW1b7ntaW2UtIBJp1UsgxqIeqAOE_1751985490 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: wx9fpsrsbqygkqeikb5p36kd4kgj1s34 X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 26CF38000C X-HE-Tag: 1751985492-120887 X-HE-Meta: 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 SHdtiYow W+L1aweNA72vV/0rWnio+sIaXoESObcnopDLZb5MFpdJmzCDfKDYaY95n7lt9FxMbqcmxAbrdYRY0iBP+axUjfbwGKigHbTcVLvFHrHICk0BK/jx3vZMOdB/aiMVkYkpGBFuURXIIQ5yrWlx5uTZXOuNebyRzCrYK6XsXQnOwc4eQIgPnoP9HcEJdx8vVvYn1Povc5n4gGmCVH8eEsvQ2EAJ+m8zV1v1R6QORf8ePmEu4jSQ2f3xnFJrHAPsDAciCJ4qsePW8PMKQ9XmBK7wMpm2OqENhSGnEKwj0K+iQhKJgZDV3kul3eTeqNVeYNIKUDRfRGfOLb2vw5qDP5KRksrLDCV9rSyYpV4+LsKRO5OCnL4MyuRnC84qoBKQ+UYL5YDXDEGaszvzDKP0D0Z2vLxwoIFqXwVVbBq5Ve8EauPX2Qt0BXHSceqg+xW98CsuhP8Ha4Hceze8rLcbV85GXgLUkXoCAkgpx3FCVmkmSF7UXSUE= 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: List-Subscribe: List-Unsubscribe: On 06.03.25 05:42, Balbir Singh wrote: > Support splitting pages during THP zone device migration as needed. > The common case that arises is that after setup, during migrate > the destination might not be able to allocate MIGRATE_PFN_COMPOUND > pages. > > Add a new routine migrate_vma_split_pages() to support the splitting > of already isolated pages. The pages being migrated are already unmapped > and marked for migration during setup (via unmap). folio_split() and > __split_unmapped_folio() take additional isolated arguments, to avoid > unmapping and remaping these pages and unlocking/putting the folio. > > Since unmap/remap is avoided in these code paths, an extra reference > count is added to the split folio pages, which will be dropped in > the finalize phase. > > Signed-off-by: Balbir Singh > --- [...] > remap_page(origin_folio, 1 << order, > folio_test_anon(origin_folio) ? > RMP_USE_SHARED_ZEROPAGE : 0); > @@ -3808,6 +3823,7 @@ bool uniform_split_supported(struct folio *folio, unsigned int new_order, > * @lock_at: a page within @folio to be left locked to caller > * @list: after-split folios will be put on it if non NULL > * @uniform_split: perform uniform split or not (non-uniform split) > + * @isolated: The pages are already unmapped Isolated -> unmapped? Huh? Can we just detect that state from the folio so we don't have to pass random boolean variables around? For example, folio_mapped() can tell you if the folio is currently mapped. -- Cheers, David / dhildenb