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Thu, 2 Nov 2023 14:29:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1698935343; bh=bRsB7LoOlwnaeDzBn85F8lO8jv7acyGjA2Bu9E6BZ2Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=M/uLoMdZ7OeZHtSdv51jpB5lwNINNYilKSiD8FCSlvz3Wd5OhVqN7DpoiuTvn8mhi HNUUEXa//lmAQ4U16ismcVo9rOtNfuc8BrCzIZLvx2pYfPkaY3OsmYoSvxxpv3NEMP SULUnKFIWBs+xxjqeYA6fjFYOPDA5cvceyUbPu/U= Date: Thu, 2 Nov 2023 15:28:58 +0100 From: Greg KH To: Pasha Tatashin Cc: Sourav Panda , corbet@lwn.net, rafael@kernel.org, akpm@linux-foundation.org, mike.kravetz@oracle.com, muchun.song@linux.dev, rppt@kernel.org, david@redhat.com, rdunlap@infradead.org, chenlinxuan@uniontech.com, yang.yang29@zte.com.cn, tomas.mudrunka@gmail.com, bhelgaas@google.com, ivan@cloudflare.com, yosryahmed@google.com, hannes@cmpxchg.org, shakeelb@google.com, kirill.shutemov@linux.intel.com, wangkefeng.wang@huawei.com, adobriyan@gmail.com, vbabka@suse.cz, Liam.Howlett@oracle.com, surenb@google.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, willy@infradead.org, weixugc@google.com Subject: Re: [PATCH v5 1/1] mm: report per-page metadata information Message-ID: <2023110216-labrador-neurosis-1e6e@gregkh> References: <20231101230816.1459373-1-souravpanda@google.com> <20231101230816.1459373-2-souravpanda@google.com> <2023110205-enquirer-sponge-4f35@gregkh> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspam-User: X-Stat-Signature: ifbtxjtxhex6cogco7sduh5noi1a84zw X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 27FC71C0012 X-HE-Tag: 1698935344-277616 X-HE-Meta: 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 VdCmbSu8 6zzukeLe1iJFh8fHV/V2+9pzZ/+W0xyumei137epsyiByE5dGEH4c3AVzXQOTDPgOT1zIVo9V643pgn50Umer6d8Cnl9eCZG3BtWPMxwH3Q5K8w9fUMsIKOOV4yNyZIhb1x7BDRLa0WSoEMryXzoxxiAGkWOSMilj9QfD01YXaXGxhiuwwUCTafhemr2N92gRLrmSyF+Pg9MJFrADeqorByElngt97XSMbhIXVC80+rfeRclUUcVKH+OPjeZEZK0q2rUeXhmR6BMZYBDSlVAl5Vo2oGMbznUTX0z0pCu7btfzaoNyF9i3a61P3EUZ18wbeUKf/9o6NuWdZW3UVM7HSfzGYt1JmQMBdQkI 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 Thu, Nov 02, 2023 at 10:24:04AM -0400, Pasha Tatashin wrote: > On Thu, Nov 2, 2023 at 1:42 AM Greg KH wrote: > > > > On Wed, Nov 01, 2023 at 04:08:16PM -0700, Sourav Panda wrote: > > > Adds a new per-node PageMetadata field to > > > /sys/devices/system/node/nodeN/meminfo > > > > No, this file is already an abuse of sysfs and we need to get rid of it > > (it has multiple values in one file.) Please do not add to the > > nightmare by adding new values. > > Hi Greg, > > Today, nodeN/meminfo is a counterpart of /proc/meminfo, they contain > almost identical fields, but show node-wide and system-wide views. And that is wrong, and again, an abuse of sysfs, please do not continue to add to it, that will only cause problems. > Since per-page metadata is added into /proc/meminfo, it is logical to > add into nodeN/meminfo, some nodes can have more or less struct page > data based on size of the node, and also the way memory is configured, > such as use of vmemamp optimization etc, therefore this information is > useful to users. > > I am not aware of any example of where a system-wide field from > /proc/meminfo is represented as a separate sysfs file under node0/. If > nodeN/meminfo is ever broken down into separate files it will affect > all the fields in it the same way with or without per-page metadata All of the fields should be individual files, please start adding them if you want to add new items, I do not want to see additional abuse here as that will cause problems (as you are seeing with the proc file.) > > Also, even if you did want to do this, you didn't document it properly > > in Documentation/ABI/ :( > > The documentation for the fields in nodeN/meminfo is only specified > in Documentation/filesystems/proc.rst, there is no separate sysfs > Documentation for the fields in this file, we could certainly add > that. All sysfs files need to be documented in Documentation/ABI/ otherwise you should get a warning when running our testing scripts. thanks, greg k-h