On Wed, Mar 11, 2020 at 10:46:15AM -0700, Daniel Colascione wrote: > 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. It might also be desirable for userland to have a way to modify the behavior of an already mounted v1 freezer. Tejun, would it be acceptable to have a flag but disable it by default, hiding it behind a kernel configuration option?
