Files
linux/kernel
Roman Gushchin cb2c4cd878 cgroup: prevent spurious transition into non-frozen state
If freezing of a cgroup races with waking of a task from
the frozen state (like waiting in vfork() or in do_signal_stop()),
a spurious transition of the cgroup state can happen.

The task enters cgroup_leave_frozen(true), the cgroup->nr_frozen_tasks
counter decrements, and the cgroup is switched to the unfrozen state.

To prevent it, let's reserve cgroup_leave_frozen(true) for
terminating processes and use cgroup_leave_frozen(false) otherwise.

To avoid busy-looping in the signal handling loop waiting
for JOBCTL_TRAP_FREEZE set from the cgroup freezing path,
let's do it explicitly in cgroup_leave_frozen(), if the task
is going to stay frozen.

Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2019-05-06 08:39:06 -07:00
..
2019-04-19 11:26:48 -07:00
2019-02-01 20:55:38 +01:00
2018-12-28 12:42:30 -08:00
2018-10-31 08:54:16 -07:00
2019-01-11 18:05:40 -08:00