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Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1vRNX5-00000005A2T-0Xng; Fri, 05 Dec 2025 04:35:03 +0000 Date: Fri, 5 Dec 2025 04:35:02 +0000 From: Matthew Wilcox To: linux-fsdevel@vger.kernel.org Cc: Zi Yan , linux-mm@kvack.org, Song Liu Subject: Removal of CONFIG_READ_ONLY_THP_FOR_FS Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: BF7E6A0006 X-Stat-Signature: 9518f18z7yj3z84j6bwa7zefqj3sthd7 X-Rspam-User: X-HE-Tag: 1764909307-413754 X-HE-Meta: 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 LaF1j8bv 8qIM2kKnLdCNn5GCEMyVbX4PG4NRhoSbbzk8Bh4FxGVs061EOKx20PXwFHmUziF1ZlZjHJKpqjFY5MGYvMdTmXPe/eyzvgl6O0VUmLK9MHpD+3d8dIMOhs+r5mtWqfDlnV8wMZY91ppwMOGYHoaRmESGgKwSKJNE/OtJjw283/c4XtCFdGNP1zDMW6LQSNan7/6acnDMrVCQQrZbPGBn4HpkZmmMLdep5fpHA6Dq93grIctbuWPjVT99+52A+7sjJIUOL 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: This is a heads-up that CONFIG_READ_ONLY_THP_FOR_FS is going to be removed during the next merge window. When it was merged in 2019, it was always intended as a temporary step towards the more general solution which ended up being merged as large folios. It has been a good feature which helped a lot, both as a way to develop other code which was eeded for large folios and it provided an immediate solution for improved performance. Now the majority of filesystems where performance is relevant have been converted to support large folios (afs, btrfs, erofs, ext4, nfs, smb, tmpfs, xfs, zonefs) with f2fs in progress. It's time to get rid of CONFIG_READ_ONLY_THP_FOR_FS. It unnecessarily bloats struct inode and it's now getting in the way of removing the old uniform split behaviour of split_huge_page_to_list_to_order(). If more work needs to be done to your filesystem to support PMD-sized folios, this would be a great time to do it ;-) There's lots of examples to learn from now; the infrastructure should all be in place, and I'll be available to help after Plumbers (December 15th). [note: all relevant filesystem mailing lists are on the bcc so as not to alarm mailing list managers]