cgroup,freezer: fix incomplete freezing when attaching tasks

An issue was found:

	# cd /sys/fs/cgroup/freezer/
	# mkdir test
	# echo FROZEN > test/freezer.state
	# cat test/freezer.state
	FROZEN
	# sleep 1000 &
	[1] 863
	# echo 863 > test/cgroup.procs
	# cat test/freezer.state
	FREEZING

When tasks are migrated to a frozen cgroup, the freezer fails to
immediately freeze the tasks, causing the cgroup to remain in the
"FREEZING".

The freeze_task() function is called before clearing the CGROUP_FROZEN
flag. This causes the freezing() check to incorrectly return false,
preventing __freeze_task() from being invoked for the migrated task.

To fix this issue, clear the CGROUP_FROZEN state before calling
freeze_task().

Fixes: f5d39b020809 ("freezer,sched: Rewrite core freezer logic")
Cc: [email protected] # v6.1+
Reported-by: Zhong Jiawei <[email protected]>
Signed-off-by: Chen Ridong <[email protected]>
Acked-by: Michal Koutný <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>

0 files changed, 0 insertions, 0 deletions