On Tue, Mar 3, 2020 at 5:48 AM Tejun Heo <tj@xxxxxxxxxx> wrote: > > Hello, > > On Wed, Feb 19, 2020 at 10:32:31AM -0800, Marco Ballesio wrote: > > @@ -94,6 +94,18 @@ The following cgroupfs files are created by cgroup freezer. > > Shows the parent-state. 0 if none of the cgroup's ancestors is > > frozen; otherwise, 1. > > > > +* freezer.killable: Read-write > > + > > + When read, returns the killable state of a cgroup - "1" if frozen > > + tasks will respond to fatal signals, or "0" if they won't. > > + > > + When written, this property sets the killable state of the cgroup. > > + A value equal to "1" will switch the state of all frozen tasks in > > + the cgroup to TASK_INTERRUPTIBLE (similarly to cgroup v2) and will > > + make them react to fatal signals. A value of "0" will switch the > > + state of frozen tasks to TASK_UNINTERRUPTIBLE and they won't respond > > + to signals unless thawed or unfrozen. > > As Roman said, I'm not too sure about adding a new cgroup1 freezer > interface at this point. If we do this, *maybe* a mount option would > be more minimal? I'd still prefer a cgroup flag. A mount option is a bigger compatibility risk and isn't really any simpler than another cgroup flag. A mount option will affect anything using the cgroup mount point, potentially turning non-killable frozen processes into killable ones unexpectedly. (Sure, you could mount multiple times, but only one location is canonical, and that's the one that's going to get the flag flipped.) A per-cgroup flag allows people to opt into the new behavior only in specific contexts, so it's safer.
