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Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1vV9Sx-000000020VP-2z91; Mon, 15 Dec 2025 14:22:23 +0000 Date: Mon, 15 Dec 2025 14:22:23 +0000 From: Matthew Wilcox To: Jinchao Wang Cc: Andrew Morton , Christian Brauner , Hannes Reinecke , Luis Chamberlain , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, syzbot+4d3cc33ef7a77041efa6@syzkaller.appspotmail.com, syzbot+fdba5cca73fee92c69d6@syzkaller.appspotmail.com Subject: Re: [PATCH] mm/readahead: read min folio constraints under invalidate lock Message-ID: References: <20251215141936.1045907-1-wangjinchao600@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251215141936.1045907-1-wangjinchao600@gmail.com> X-Rspam-User: X-Rspamd-Queue-Id: 3FB4B140019 X-Rspamd-Server: rspam04 X-Stat-Signature: f7nmtjyjop8xeq38csota9mzememifuo X-HE-Tag: 1765808547-21197 X-HE-Meta: U2FsdGVkX1/iPsqe1K7d03UkAtL+n7rclVfoM/cZKPK5y0xxW76610gyxJ+AvBHkIsLTDrwG9hdYlIZd/Lk61xSPeyD5PK3mXVe7YsSLUZbdGnHfHY/JxQlyuC7nOp5PwMvmcRa6a4Lde0RPh4E1o7oBV2Aq1BhNVaYxbotej6HGRqnVJJiQOjmk7xoOGfUyV9K/xMxqMc3OjrCDxct/cDyVMHQ1PaPo//8Ftlv2fgleaqvCRlUR0lKvMwu9keCOzMaB16Ixwx0orTIH2052Uhl5SwB0C2b9PTCaPoNuB+D3JYnDWYklxkH3ioj2uDWPq7DEvJn9J67OuTF0dzUHd6s+fbHVWBWSlRiHHDqcv2mBNNUSJpELge8cmYk+jsTZT4zKPlAGRWkoin00bNqTVyLhgVuF6CAnBuP2tCMpREN+AUp6f728GLUr8ZAQYQFLGEkI45Uqn+yuebu1t27SdcaCd2ASiiThKWUknJMeA5Fo5yv7slpTl0xDLldznxJtdUk9q/TYt+m4Ly+VlwoIo2TCwS5mVHjlz5U7maMDUlOYQCmwJDuK+dAn0lTVj1i+A1/D2p6aFip/EoR1s7ztTgesmq/u8lCLcWhcoudqUSEm77fCi6a9oovdW/i+VfsruNLpAh+buNyqYgB3vWp23mTu+yOqtNeOSjpu7o60mu8TTALCb32g9J3vyAIjezsIiaUrzWPbYi94hJ70fN+QFjEdTi4BBI0YVPyHWa6dApdxHLCMMv7lijv6YbDRDlmlFNEos8xvE1YfDZbxyM+lLHMWi/3qCQ636mD9HVmJVC0X1AdTOtlt8Z1QM7vs44YBJALzRA1qMbgqeoDnQrYHbVF/QXLtyOXI8xMgTYg4ZbiAJXzKR/GAVHLpkju6h9BghHfewqG31qadV4dK5nZ1Qe4TmGYV41JSu/3+QAAldPJ3EiXSnj21VhavBSBbYtlgTBVrLiDaOhOi7poW9yr ZddLdtLQ LG+1mH1eGwc8kjEJ7hn2dsPhdKTTDZsr37faL7F6ylViqMElH88AjjfiIb3se6sSRzSC8Z+zy6+GhhFRtH/AIfyZFLePloqk5hxv/9Kg86KZLhgpfM8kSPTLE+/2pf4dgjRVLPWoH0WOb2WZ9R/z1VKg1IIdgTjaF285SZaUze7BbpGDOZwrhdDIFwPml4tX37EHI5qmP4A/HiHaCZiyiig62p8zZL7jPLfqebmMvvQR4/7kPVDXV3vTv2v6mWPyfXb1s7jdxQveUN4wP23qBz4Asl0u/eQ+K0Xi48ebdQX8f+Pm2myamgh+m9OC54PM5m5YiQStIIOMPwuKAaEJVu21+1lnDk/zF5ijrx49F+s1N1mS0qulJrIEprA== 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 Mon, Dec 15, 2025 at 10:19:00PM +0800, Jinchao Wang wrote: > page_cache_ra_order() and page_cache_ra_unbounded() read mapping minimum folio > constraints before taking the invalidate lock, allowing concurrent changes to > violate page cache invariants. > > Move the lookups under filemap_invalidate_lock_shared() to ensure readahead > allocations respect the mapping constraints. Why are the mapping folio size constraints being changed? They're supposed to be set at inode instantiation and then never changed.