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[2003:cb:c717:6d00:aebb:127d:2c1a:7f3a]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3718985ae26sm2354517f8f.55.2024.08.15.14.41.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 15 Aug 2024 14:41:24 -0700 (PDT) Message-ID: <7e7ee391-6f4d-4d36-ace5-4f8ca81479bc@redhat.com> Date: Thu, 15 Aug 2024 23:41:23 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC] Merge PG_private_2 and PG_mappedtodisk To: Matthew Wilcox , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org References: 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: 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 X-Rspam-User: X-Stat-Signature: m4jqaqbuoyn7hhxx9m9o7w97spcru7ej X-Rspamd-Queue-Id: C5F1A20006 X-Rspamd-Server: rspam11 X-HE-Tag: 1723758088-37756 X-HE-Meta: U2FsdGVkX19aNIl9t/CeHOwuWyN9sqLSM+oQVSNzTZCHr6Uikw1zxfslwDzK7q/mUXj6Zt0ql5m8Sik6wFZiQ0HKDFGvs8d77vFCP7P5tUUrHlKI8kJeN6Ir/PPv2g2viZ6ThMxt8p+u5SOqnp9Ps96Xf1AM6Y37B5YDdomsz7s26E6Z7CNlFc2AugvrfVoxodADeABofqWykj5TyeOH+UclrFFRNWzOkXz24XXQnpohKGnnbaG6IzyVMOtAqJrAR3rrN5rzjD9RGfxvwV2eIpjqEBxOTUBciSSDofoNe7Gpp57EbYKcxquM2jfD+FnMszS/7QXLXERSxVJZrQIIux1HOZItn3oMOB0aR0JwhEtMa3z51TuYzcUTSc4bOKI6raT1xBOcpWaZF/729f+L92Qkv6M/qauyxlOMDpNnHahRH12O0zamflg8Jrt94LENecwbB0lXXExfCB8l7Cyr2ra8Q3NE3FPprHjyRj2nxvrRHv9wQIVRynp2NMU57iF39fC+Ztf2HE9V+p2pHX0BumbkHJKKs7ffYJYUuUkK82fGNWOxQwqkkp9XsUF6oLEt7dqNHXrKX6VdnicpFGiQz0F/kyQ/uDPoFGVwtu9dd4bhI1qLzUvxiXKMVRrBg/Jq4PXLqwjMIKFgHlG7o0prBddmLlW4lbLh5yn/grV/xjW8KjnK8+MTy7IP6duQmeCOHilsByX+iixh9vw94IhSkky9CiB2jdT2PXCFcAnsZdD9h2bil6iHliRhVZKAyEslwisQgfYHk49E4EDTyuwpDIie5Z0DVvMYwYycdPXXVCFAC5rXrE712N3co5I3y4sfPtMA5CqLi8YEdP7Ll1GkhXb1qqR/e2yydatpTYVepnOrswuqUZjyZc263BIqp8H554E5/4bB1Dkh1Sz3ZD2gZvd1RqRH73aF71BaS+ZkUeP+zieUAEM6bTnNvHEppShVLPlsfwXbWoClY+XwgBF qCyIzhia i4hacS0XfVWYggN/xgAyCIU8W5+l1vv8VXOj+7QcZ+MSv/O2zqwDgKU3/l2IgRcoTkpRRVvWN0tHs5DLdeAK9u3b2Dw5RqTxIGSBmkRBqK/ZK7N7N5qkZa/XgSIHHIBGdbeLD1i0MKeSN+NK/uRo9kAlXwIfC7JtleiBiaTmUM682yGVzMJiTEVJ+n7i7hTgc9hMIW1o+Pvqw7R8Vb5BhoVvqGFnrAsQejlIJsrTyUNnBXvsDKSyTz5rfKbdwxwWuhqNMgRlmvRGi3tFJTbw4w5XsCdT2jqkIoOSAdplACCNg0UIWofgSXqvVDFFjU9ha2lewTK4I7oh6dHgrFmP1vUJG2YHBQJEYRgkRm8q7DVNB/PyfRS6FR0uLuR1/HKNUIvt6TXNUVTlpLINc3Cu9EL+XoQ6zCuvGF86e 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 14.08.24 19:36, Matthew Wilcox wrote: > I believe these two flags have entirely disjoint uses and there will > be no confusion in amalgamating them. > > Anonymous memory (re)uses mappedtodisk for anon_exclusive. > Anonymous memory does not use PG_private_2. Also not when they are in the swapcache, right? > > $ git grep -El '(folio.*mappedtodisk)|PageMappedToDisk' > fs/buffer.c > fs/ext4/readpage.c > fs/f2fs/data.c > fs/f2fs/file.c > fs/fuse/dev.c > fs/mpage.c > fs/nilfs2/file.c > fs/nilfs2/page.c > include/trace/events/pagemap.h > mm/memory.c > mm/migrate.c > mm/truncate.c > > $ git grep -El '(folio.*private_2)|PagePrivate2' > fs/btrfs/ctree.h > fs/ceph/addr.c > fs/netfs/buffered_read.c > fs/netfs/fscache_io.c > fs/netfs/io.c > fs/nfs/file.c > fs/nfs/fscache.h > fs/nfs/write.c > include/linux/netfs.h > include/linux/pagemap.h > mm/filemap.c > mm/migrate.c > > The one thing that's going to stand in the way of this is that various > parts of the VFS treat private_2 as a "wait for this bit to be clear", > due to its use in fscache (which is going away). > > So my approach here is going to be: > > - Rename mappedtodisk to be PG_owner_priv_2 (add appropriate aliases) > - Switch btrfs to use owner_priv_2 instead of private_2 > - Wait for the fscache use of private2 to finish its deprecation cycle > - Remove private_2 entirely > > Sound good? Yes, one step into the right direction. -- Cheers, David / dhildenb