On Wed, Nov 25, 2020 at 02:42:37PM +0100, Peter Zijlstra wrote: > On Tue, Nov 17, 2020 at 06:19:56PM -0500, Joel Fernandes (Google) wrote: > > From: Josh Don <josh...@google.com> > > > > Google has a usecase where the first level tag to tag a CGroup is not > > sufficient. So, a patch is carried for years where a second tag is added > > which > > is writeable by unprivileged users. > > > > Google uses DAC controls to make the 'tag' possible to set only by root > > while > > the second-level 'color' can be changed by anyone. The actual names that > > Google uses is different, but the concept is the same. > > > > The hierarchy looks like: > > > > Root group > > / \ > > A B (These are created by the root daemon - borglet). > > / \ \ > > C D E (These are created by AppEngine within the container). > > > > The reason why Google has two parts is that AppEngine wants to allow a > > subset of > > subcgroups within a parent tagged cgroup sharing execution. Think of these > > subcgroups belong to the same customer or project. Because these subcgroups > > are > > created by AppEngine, they are not tracked by borglet (the root daemon), > > therefore borglet won't have a chance to set a color for them. That's where > > 'color' file comes from. Color could be set by AppEngine, and once set, the > > normal tasks within the subcgroup would not be able to overwrite it. This is > > enforced by promoting the permission of the color file in cgroupfs. > > Why can't the above work by setting 'tag' (that's a terrible name, why > does that still live) in CDE? Have the most specific tag live. Same with > that thread stuff. > > All this API stuff here is a complete and utter trainwreck. Please just > delete the patches and start over. Hint: if you use stop_machine(), > you're doing it wrong. > > At best you now have the requirements sorted.
+1, just remove this patch from the series so as to unblock the series. Balbir Singh.
