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 060F4264600; Tue, 4 Mar 2025 16:55:03 +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=1741107304; cv=none; b=GNSVZiQwybBsyiJKNeYijdhgYgcsOj/4wPRi6aa3Cc3+d28FSwyUtzmMdW3MJkbu47amtrf/4IgR3PP+i6C0ei1y/Freqc08kyCxTjG77G4Be8K+/yZA3b7T2AQ37S8g2qHdgQqWa9uN82s2fjSPK3+usIk7BNzCAKkAenaGFBs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741107304; c=relaxed/simple; bh=b0tgUtFT8jt9U9rAUFsewLIDZQyfCwT4CxSxsMn617o=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=gmHEktfNPTecthqH75dw/KIJDCcLJGdIRb8qskxiYiHW/EDfIAuN1FYh8CO3PEIfplN8wJEIgtEg6qbK6ib9oeS08JzWZPnOzu2I/Sg+Jf7ILLstWJZmQkpNPa4UwHrfZMQ4JQ7B4rF7u6/ad392VYjjnfHX8iYNyEyg6SXxc8g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=q2Rq8z9/; 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="q2Rq8z9/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 50726C4CEE5; Tue, 4 Mar 2025 16:55:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1741107303; bh=b0tgUtFT8jt9U9rAUFsewLIDZQyfCwT4CxSxsMn617o=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=q2Rq8z9/nPxSEiZwUtvczIg9EPcyL/IYN32H60rL/gqIycMJKiRuQOIj/pgZ5I03D 9WrgshNJEhKU58Q0KI1iEYJRRsMb21f6LT/1gSL1JI6dKDQHSKeRWNc3mW254Rgr9C IcYGH3P5YQwo04ZoVKexsrSAJEa/d+fR+QLJ+eS01xz3sWQAe/OIFc4YOPs68yaKsz Q6Z5jjf6RsKkieIbBGTjmnSsklG7voc7jrETAn7MdANlC3bgIe2UD+3ju/eb0ROkQx TFsSVIgnKa0cmQK+p9wXsiEQIwRZyqGXOIwAGUvSxjkpN1+dFyVwIKYufIANYR/JYS 9sbEy8w/oVrkw== Date: Tue, 4 Mar 2025 06:55:02 -1000 From: Tejun Heo To: Michal =?iso-8859-1?Q?Koutn=FD?= Cc: cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Josef Bacik , Jens Axboe , Johannes Weiner , Waiman Long Subject: Re: [PATCH 4/9] cgroup: Print warning when /proc/cgroups is read on v2-only system Message-ID: References: <20250304153801.597907-1-mkoutny@suse.com> <20250304153801.597907-5-mkoutny@suse.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20250304153801.597907-5-mkoutny@suse.com> On Tue, Mar 04, 2025 at 04:37:56PM +0100, Michal Koutný wrote: > As a followup to commits 6c2920926b10e ("cgroup: replace > unified-hierarchy.txt with a proper cgroup v2 documentation") and > ab03125268679 ("cgroup: Show # of subsystem CSSes in cgroup.stat"), > add a runtime message to users who read status of controllers in > /proc/cgroups on v2-only system. The detection is based on a) > no controllers are attached to v1, b) default hierarchy is mounted (the > latter is for setups that neven mount v2 but read /proc/cgroups upon > boot when controllers default to v2). I'm hoping that we could deprecate /proc/cgroups entirely. Maybe we can just warn whenever the file is accessed? Thanks. -- tejun