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Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1rfOIO-00000005q7d-0iCL; Wed, 28 Feb 2024 18:04:44 +0000 Date: Wed, 28 Feb 2024 18:04:44 +0000 From: Matthew Wilcox To: Kent Overstreet Cc: Linus Torvalds , Dave Chinner , Luis Chamberlain , lsf-pc@lists.linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-mm , Daniel Gomez , Pankaj Raghav , Jens Axboe , Christoph Hellwig , Chris Mason , Johannes Weiner Subject: Re: [LSF/MM/BPF TOPIC] Measuring limits and enhancing buffered IO Message-ID: References: <4rde5abojkj6neokif4j6z4bgkqwztowfiiklpvxramiuhvzjb@ts5af6w4bl4t> <72fsezoex3soqbjsuabjzyzhlbeouy2uu75h5hcia3stwfv7q4@batxjbhkcnnc> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <72fsezoex3soqbjsuabjzyzhlbeouy2uu75h5hcia3stwfv7q4@batxjbhkcnnc> X-Rspamd-Queue-Id: F414C4000F X-Rspam-User: X-Stat-Signature: rta7zrmyx1kstyzd1fk4yccmqr3tf9m3 X-Rspamd-Server: rspam03 X-HE-Tag: 1709143505-392955 X-HE-Meta: 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000012, 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 Wed, Feb 28, 2024 at 12:34:41PM -0500, Kent Overstreet wrote: > But even better would be if we could get lockdep to support folio locks, > then we could define a lockdep comparison function. Of course, there's > no place to stick a lockdep map, but I think technically lockdep could > do everything it needs to do without state in the lock itself, if only > that code didn't make my eyes bleed whenever I have to dig into it... I don't think lockdep can support folio locks. They're taken in process context and (for ->read_folio) released in interrupt context. Also we can return to userspace while holding folio locks (I believe ...) DEPT claims to be able to handle them, but I haven't looked in detail.