Hi Tejun, On 11/13, Tejun Heo wrote: > > > OK, please forget for now, but perhaps it would be more clean to add > > JOBCTL_TRAP_FREEZE to the JOBCTL_PENDING_MASK check in recalc_sigpending() > > and change get_signal to check JOBCTL_TRAP_MASK | JOBCTL_TRAP_FREEZE; and > > I am not even sure cgroup_freezer_enter() should live in do_jobctl_trap(). > > I'm sure you're aware of the context but just to refresh - one thing > which was really broken about cgroup1 freezer was that it piggybacked > on hibernation freezer and put frozen tasks in a state which is > undefined when seen from userspace - they're just stuck in D sleep > somewhere in the kernel. That's fine when the whole system is not > gonna be running, but not when only a subportion is being frozen. Thanks, I see. > So, the primary goal of cgroup2 freezer is putting the tasks in an > equivalent state as jobctl stop. It's a jobctl stop but controlled by > cgroup frozen state, meaning that they can be killed, PTRACE_SEIZE'd > and INTERRUPT'ed (PTRACE_ATTACH doesn't work as signal delivery should > be blocked but that's fine) and so on. And I agree, JOBCTL_TRAP_FREEZE looks fine. Just somehow I _feel_ that we can improve this logic a bit, but let me repeat that of course I can be easily wrong and I didn't even read the patch yet. Oleg.
