The existing freezer propagation logic improperly reduces
nr_frozen_descendants by an increasing 'desc' counter during unfreeze,
leading to:
- Premature parent cgroup unfreezing
- Negative descendant counts
- Broken hierarchy state consistency
Scenario demonstrating the bug:
1. Create hierarchy A->B->C
2. Freeze C (A/B freeze via propagation)
3. Freeze A->D (separate branch)
4. Unfreeze C -> A incorrectly unfreezes despite frozen D
Fixes: 711f763 ("freezer,cgroup: add freezer.stats subsystem")
Signed-off-by: Umar cynexium@xxxxxxxxx
---
kernel/cgroup/freezer.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/cgroup/freezer.c b/kernel/cgroup/freezer.c
index e9c15fbe5d9b..d384df2f53c2 100644
--- a/kernel/cgroup/freezer.c
+++ b/kernel/cgroup/freezer.c
@@ -304,6 +304,7 @@ void cgroup_freeze(struct cgroup *cgrp, bool freeze)
*/
if (dsct->freezer.e_freeze > 0)
continue;
+
WARN_ON_ONCE(dsct->freezer.e_freeze < 0);
}
--
2.47.1
