Hello, On Tue, Jul 09, 2024 at 03:05:21PM +0100, Pavel Begunkov wrote: > > ----------------------------------------------------------------------- > > Either way I have no idea whether a cgroup_task_frozen() task should > > react to task_work_add(TWA_SIGNAL) or not. > > > > Documentation/admin-guide/cgroup-v2.rst says > > > > Writing "1" to the file causes freezing of the cgroup and all > > descendant cgroups. This means that all belonging processes will > > be stopped and will not run until the cgroup will be explicitly > > unfrozen. > > > > AFAICS this is not accurate, they can run but can't return to user-mode. > > So I guess task_work_run() is fine. > > IIUC it's a user facing doc, so maybe it's accurate enough from that > perspective. But I do agree that the semantics around task_work is > not exactly clear. A good correctness test for cgroup freezer is whether it'd be safe to snapshot and restore the tasks in the cgroup while frozen. If that works, it's most likely fine. Thanks. -- tejun
