From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A886679B83 for ; Wed, 28 Feb 2024 18:04:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709143493; cv=none; b=YzeOvaEfD/atyZwtiXVjZ4nAc5br4PzICc7wdGnHKm/iUN/EQzS5oMV79IBi/BtiNtMF9l4yqVNsKj0sbxTbsi6Gc7HlInY1eDGa7nXtwXnFPiWwjxswhl1likffOhfeJDfp8xxQAQeJ8jTDiWsUdZ5EXTay3WBKP60yFhnvDW8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709143493; c=relaxed/simple; bh=oabw/X8XF+Boj1BSGHds7dPKmBzdgs7nfuXKfJWHtC8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=DeRKGUEuk6S4q+Wa99m7Csq3LDN3DpRpL5F/05USuCNYvfI4WjHkJaLiG91HT9eSJOqyPGamEmLPeIwFbIf5ERXOIG7icTSUUD02Qy6JEV4dBZi/51VXeaNb7hqnTVy15RwQwT1hkcWcrqDB2IHm8A1dCUtg2+Ok+ZtxiG4olqc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=ILNN4HEV; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="ILNN4HEV" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=zpae6JWvwsxyRNz19RcMzmZiYrN3iievkxJaXRzgsOg=; b=ILNN4HEV828WiuM3dN1kuV4dI0 kIRyCwC/0SkSsrKmFYvbC1UWtWOhKi0tUdQME7u/gBECAIxrVcjqUIGs9S7JY0oSwX/UFeKK4QO77 SiZ3K6I2pHs3ANrOjQRt+Os3aq1MXIjNvmHyQPhEWAvHORK3byuZdgSfh3SGOuOKjczelEA+wVTkC WEzmCXSZghRoIUG5YoIrmN7xSkxEGxv8qVOvzLbtFdQvaCkYoP6wpyZyK7VSYDVUwIYYdhDmDGNaK UfbCxSheZjWCL2YiSbKMcCl9IeDyx+/Psqd45GA81f3Tp7kb6sWVU9HxhV0eyTYyQ5GQMI7mjemiM AvZxoxDg==; 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> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <72fsezoex3soqbjsuabjzyzhlbeouy2uu75h5hcia3stwfv7q4@batxjbhkcnnc> 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.