On Tue, Apr 06, 2021 at 12:08:50PM -0400, Tejun Heo wrote: > I see. Yeah, if we really need it, I'm not sure it fits in cgroup interface > proper. As I wrote elsewhere, these things are usually implemented on the > originating subsystem interface with cgroup ID as a parameter.
This would be something like: prctl(PR_SCHED_CORE, PR_SCHED_CORE_SHARE_FROM, cgroup-fd, PIDTYPE_CGROUP, NULL); right? Where we assign to self the cookie from the cgroup. The problem I see with this is that a task can trivially undo/circumvent this by calling PR_SCHED_CORE_CLEAR on itself, at which point it can share with system tasks again. Also, it doesn't really transfer well to the group/tasks thing. When a task joins a cgroup, it doesn't automagically gain the cgroup properties. Whoever does the transition will then also have to prctl() this, which nobody will do.
