From 37fb58a7273726e59f9429c89ade5116083a213d Mon Sep 17 00:00:00 2001 From: Chen Ridong Date: Wed, 18 Jun 2025 07:32:17 +0000 Subject: [PATCH] cgroup,freezer: fix incomplete freezing when attaching tasks MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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: stable@vger.kernel.org # v6.1+ Reported-by: Zhong Jiawei Signed-off-by: Chen Ridong Acked-by: Michal Koutný Signed-off-by: Tejun Heo --- kernel/cgroup/legacy_freezer.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/kernel/cgroup/legacy_freezer.c b/kernel/cgroup/legacy_freezer.c index 039d1eb2f215..507b8f19a262 100644 --- a/kernel/cgroup/legacy_freezer.c +++ b/kernel/cgroup/legacy_freezer.c @@ -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); } } -- 2.50.1