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Thu, 9 Jan 2025 10:21:10 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id IylsKRajf2crEAAAD6G6ig (envelope-from ); Thu, 09 Jan 2025 10:21:10 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id 58FDAA0887; Thu, 9 Jan 2025 11:21:02 +0100 (CET) Date: Thu, 9 Jan 2025 11:21:02 +0100 From: Jan Kara To: Lorenzo Stoakes Cc: lsf-pc@lists.linux-foundation.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Subject: Re: [Lsf-pc] [LSF/MM/BPF TOPIC] The future of anon_vma Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 79021180007 X-Stat-Signature: ecm66uzqcsrb7izs6qcobr5mdmdz6fzp X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1736418072-447648 X-HE-Meta: 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 DaWK0NkG Reuhrbc+hIlMc1fBRiKC0IVxDFes6AlO77nHXQydV7OHzZTaStlb2TL1bbG7LhaOXgul5sz1rJ8GDoMScrF3o4MDf5VN0m2NTea4vTsHFENoxS/JUFACJ4izhl59XRXmUgkiLdWm6sADonN4o5BdVYfd1r4HjN0F3rvALKq2fnYsjFdL7YnMLeHX0BAzDE7H6WAgi0RFRBbFhdgAkPdbC0Y8BMaiLo3/NBmiFjmWgiu9PdWk6lVweiyPxjerEF3MSu9wOWKmT/BTpe3w1lWGq9aHfmTzbfWjlkyVHuub9rTzyliusX3u1/QtkNQZA58y5o8BxxYjfEir2qdDsBG05WkDBJTfS2hJAz9xSf6+0kj7cmZqCOcANrSUV1dkwLwKo1dtb0UcQ1KkFebmQ+qWbq3fvUFUSfcoCGIfwkzdHI2gWuNXg1WzEU+ZhENwCh3u1uDQC X-Bogosity: Ham, tests=bogofilter, spamicity=0.197679, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi! On Wed 08-01-25 22:23:16, Lorenzo Stoakes via Lsf-pc wrote: > A future where we unify anonymous and file-backed memory mappings would be > one in which a reflinks were implemented at a general level rather than, as > they are now, implemented individually within file systems. > > I'd like to discuss how feasible doing so might be, whether this is a sane > line of thought at all, and how a roadmap for working towards the > elimination of anon_vma as it stands might look. As you can imagine this has been discussed in the past and some folks are very interested in saving page cache memory for some heavily reflinked container setups or for various FUSE filesystems. So if someone manages to come up with a feasible design, the usecases are there. I think reading e.g. [1] and comments below it is a good preparation for the session to get some idea what challenges are there :). Honza [1] https://lwn.net/Articles/717950/ -- Jan Kara SUSE Labs, CR