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b=YUVpqo7YIli6QJVeQfZlT5gOAr7WLxWr8FqAVyU/brJA8ScMFt8u/xKvANNh4Cuy0 JNs1riyORN9FuEtA/u2bZE4JpgP44IZ26wCnQxd1Iztie1foy8Wjpw54/2r4LEVrDr v2A7TFHVxmp5lMPHApZrYjkObKmE0UF3E1GrzBiVJfrpE9zAsRdeeMGhzvIxtV9rQl LGmKq90qLox/+bBoOeHBpJTWIRbyhgLlewnp0qweguGCMS8y2FDl38VcEcBYROmmKW coJgGd0gQ+bai1Iuf8+oH/uRqZNv0P8vEEog1n/hYI8mk65rNynGizdrTVYoEVy2zX SPLk5IwMELUtA== Date: Fri, 11 Jul 2025 12:15:07 -1000 From: Tejun Heo To: Michal =?iso-8859-1?Q?Koutn=FD?= Cc: Ben Hutchings , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Zefan Li , Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , Chen Ridong , 1108294@bugs.debian.org Subject: Re: [PATCH 4/4] cgroup: Do not report unavailable v1 controllers in /proc/cgroups Message-ID: References: <20240909163223.3693529-1-mkoutny@suse.com> <20240909163223.3693529-5-mkoutny@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Stat-Signature: tftjupp41ig43uxa5rzja1sk5trfrsa1 X-Rspamd-Server: rspam06 X-Rspam-User: X-Rspamd-Queue-Id: C17FCC0002 X-HE-Tag: 1752272109-232546 X-HE-Meta: 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 qiXl4Pjx r0m7ng946SEI0LzaMyjHMvw0xjSh5w6+SYfbPqZWrXJhlZeBFSxD7St6EVxHJ/Gs55EpBRqrPL18mroKbLkiEBMvLYPS6xdGUvStqxf0x220akdqXXpt1wphlRRtR9e/fE89xGsj+XxAlAclv2t1Xo+Xkr6LfgfRjOwoSz57r7RmZeN1Ojz6go8JcD62FgMEdER5fpT4Qimlj2v4/Ta73y3J1byB5te6sqtH2gMiGug4HIfzcgIn+Yyxoz71vGksTATlJmvUpE6Qg0xnJFE79zkwZDqJ8kN2BNYQ+9QuGenAS6yc= 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 Fri, Jul 11, 2025 at 03:10:44PM +0200, Michal Koutný wrote: > Hello Ben. > > On Wed, Jul 09, 2025 at 08:22:09PM +0200, Ben Hutchings wrote: > > Would you consider reverting this change for the sake of compatibility? > > As you write, it's not fatally broken and it may be "just" an issue of > container images that got no fresh rebuild. (And I think it should be > generally discouraged running containers with stale deps in them.) > > The original patch would mainly serve legacy userspace (host) setups on > top of contemporary kernel (besides API purity reasons). Admittedly, > these should be rare and eventually extinct in contrast with your > example where it's a containerized userspace (which typically could do > no cgroup setup) that may still have some user demand. > > So, I'd be more confident with the revert if such an adjustment was > carried downstream by some distro and proven its viability first. Do you > know of any in the wild? I think we still want to deprecate /proc/cgroups but given that there are impacted users maybe we can bring it back under a boottime param w/ warning? Thanks. -- tejun