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Mon, 15 Dec 2025 17:37:54 -0800 (PST) Date: Tue, 16 Dec 2025 09:37:51 +0800 From: Jinchao Wang To: Matthew Wilcox 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: X-Rspam-User: X-Rspamd-Queue-Id: 01BE940002 X-Rspamd-Server: rspam10 X-Stat-Signature: 8gb5ket31g3q3w6i6iomygu71335zsx9 X-HE-Tag: 1765849075-624809 X-HE-Meta: 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 Rt4U5mLU 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 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 02:22:23PM +0000, Matthew Wilcox wrote: > 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. They can change after instantiation for block devices. In the syzbot repro: blkdev_ioctl() -> blkdev_bszset() -> set_blocksize() -> mapping_set_folio_min_order()