Commit 37fb58a7 authored by Chen Ridong's avatar Chen Ridong Committed by Tejun Heo
Browse files

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: f5d39b02 ("freezer,sched: Rewrite core freezer logic")
Cc: stable@vger.kernel.org # v6.1+
Reported-by: default avatarZhong Jiawei <zhongjiawei1@huawei.com>
Signed-off-by: default avatarChen Ridong <chenridong@huawei.com>
Acked-by: default avatarMichal Koutný <mkoutny@suse.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent c853d187

kernel/cgroup/legacy_freezer.c

+1 −2
Original line number Diff line number Diff line
@@ -188,13 +188,12 @@ static void freezer_attach(struct cgroup_taskset *tset) 
		if (!(freezer->state & CGROUP_FREEZING)) {

			__thaw_task(task);

		} else {

			freeze_task(task);



			/* clear FROZEN and propagate upwards */

			while (freezer && (freezer->state & CGROUP_FROZEN)) {

				freezer->state &= ~CGROUP_FROZEN;

				freezer = parent_freezer(freezer);

			}

			freeze_task(task);

		}

	}