From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 F369E7FBD9; Wed, 7 Feb 2024 15:52:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707321125; cv=none; b=rzwMcSxkdI+S6o7jSrlyGaRsuUGKS+LIRyTghzFY5ueqVs2BWzoiDv/OdiIiYonA7dFyyWo5dvsf2kESW3B5ZGfmM/iGZh84/wZS/lU1ajEedyWdWnzlxWppNXIUW3QO20I1C5EUJnSYvvbcWF0TKiKSnC/c1BzJbHXLeEszP2o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707321125; c=relaxed/simple; bh=/1x7h2DpHjWcd/k76A8g5THiTurxMbwv+SYlEW+93sc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=q6hng+cGwy959ErJkpp6V5JzKjivlCDbLsPZ4feC9upV8jiSDOZlxwE8ClUV9Zj7zNhF14PwfG3SOHaDr/hg3vsuxuZgI5RKUDKlRN9/O3/VErZ1PpqJ8sboLE9DzqFKfRCRS7BB8MdDX8QLurUbfXGD1mPn87+HQH2sz3QxcA4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=S4roDxo8; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="S4roDxo8" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9D9B4C43394; Wed, 7 Feb 2024 15:52:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1707321123; bh=/1x7h2DpHjWcd/k76A8g5THiTurxMbwv+SYlEW+93sc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=S4roDxo8tVqC2GezTlb3cfXFcp6weQcwLaiGZmdf1pdhhuOhtMsuGhDXsDCMV8GbO RLxAo3vtpqHJdWUBeO1ZdBUc+YJEiBqPKnzeW10gKgdzx5yAj262qNEjatFr2oewA5 U96gkG8+cuJWYr/hLXC31VNHfddrz7/y70HWgLAxw3ppS44aI4YAdO6JffVBmwOlG8 XU9HW6HuV+8zPXv4xQ3gBEg6Ps5noXk7cufMK2v4qV4yePWova47vaD8FNN7s7EdTb NB9oCYbsmwivsZGgDOIpD/iQoZTqpkGenaDhqgpVnREaQgX0b1oUD9pyX7pTlppedD uLYLbPbnYYeQg== Date: Wed, 7 Feb 2024 17:51:44 +0200 From: Mike Rapoport To: Matthew Wilcox Cc: lsf-pc@lists.linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org, linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org, linux-nvme@lists.infradead.org, bpf@vger.kernel.org Subject: Re: [LSF/MM/BPF TOPIC] Reclaiming & documenting page flags Message-ID: References: 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: On Sun, Feb 04, 2024 at 09:34:01PM +0000, Matthew Wilcox wrote: > On Sun, Feb 04, 2024 at 11:39:33AM +0100, Mike Rapoport wrote: > > On Mon, Jan 29, 2024 at 04:32:03AM +0000, Matthew Wilcox wrote: > > > Our documentation of the current page flags is ... not great. I think > > > I can improve it for the page cache side of things; I understand the > > > meanings of locked, writeback, uptodate, dirty, head, waiters, slab, > > > mlocked, mappedtodisk, error, hwpoison, readahead, anon_exclusive, > > > has_hwpoisoned, hugetlb and large_remappable. > > > > > > Where I'm a lot more shaky is the meaning of the more "real MM" flags, > > > like active, referenced, lru, workingset, reserved, reclaim, swapbacked, > > > unevictable, young, idle, swapcache, isolated, and reported. > > > > > > Perhaps we could have an MM session where we try to explain slowly and > > > carefully to each other what all these flags actually mean, talk about > > > what combinations of them make sense, how we might eliminate some of > > > them to make more space in the flags word, and what all this looks like > > > in a memdesc world. > > > > > > And maybe we can get some documentation written about it! Not trying > > > to nerd snipe Jon into attending this session, but if he did ... > > > > I suspect Jon will be there anyway, but not sure he'd be willing to do the > > writing :) > > > > I was going to propose the "mm docs" session again, but this one seems more > > useful than talking yet again about how hard it is to get MM documentation > > done. > > I'm doing my best to write documentation as I go. I think we're a bit > better off than we were last year. Do we have scripts to tell us which > public functions (ie EXPORT_SYMBOL and static inline functions in header > files) have kernel-doc? And could we run them against kernels from, say, > April 2023, 2022, 2021, 2020, 2019 (and in two months against April 2024) > and see how we're doing in terms of percentage undocumented functions? We didn't have such script, but it was easy to compare "grep EXPORT_SYMBOL\|static inline" with ".. c:function" in kernel-doc. We do improve slowly, but we are still below 50% with kernel-doc for EXPORT_SYMBOL functions and slightly above 10% for static inlines. Although with static inlines it's quite possible that the percentage of actual public API documentation is higher because some of the functions in inlcude/linux/ are only used inside mm. There are also APIs that are not EXPORT_SYMBOL, but I didn't find an easy way to check how well there are documented. EXPORT_SYMBOL version funcs docs percent v5.0 514 177 34 v5.6 538 208 38 v5.12 550 209 38 v5.17 580 228 39 v6.3 580 235 40 v6.8-rc1 565 238 42 static inline version funcs docs percent v5.0 581 33 5 v5.6 596 41 6 v5.12 629 42 6 v5.17 746 74 9 v6.3 867 95 10 v6.8-rc1 944 116 12 > There's also the problem of getting long-form documentation done. > But I think that's a different problem from getting kernel-doc written. > Looking at the 55 commits in the last year to Documentation/mm, we seems > to be doing a pretty good job of keeping the documentation we have up > to date. Just not a great job of adding new documentation. I agree that long-form documentation is a different problem from getting kernel-doc written and we are not doing a great job in writing new documentation. -- Sincerely yours, Mike.