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linux/kernel/cgroup
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Chen Ridong 8594813132 Revert "cgroup_freezer: cgroup_freezing: Check if not frozen" 
[ Upstream commit 14a67b42cb ]

This reverts commit cff5f49d43.

Commit cff5f49d43 ("cgroup_freezer: cgroup_freezing: Check if not
frozen") modified the cgroup_freezing() logic to verify that the FROZEN
flag is not set, affecting the return value of the freezing() function,
in order to address a warning in __thaw_task.

A race condition exists that may allow tasks to escape being frozen. The
following scenario demonstrates this issue:

CPU 0 (get_signal path)		CPU 1 (freezer.state reader)
try_to_freeze			read freezer.state
__refrigerator			freezer_read
				update_if_frozen
WRITE_ONCE(current->__state, TASK_FROZEN);
				...
				/* Task is now marked frozen */
				/* frozen(task) == true */
				/* Assuming other tasks are frozen */
				freezer->state |= CGROUP_FROZEN;
/* freezing(current) returns false */
/* because cgroup is frozen (not freezing) */
break out
__set_current_state(TASK_RUNNING);
/* Bug: Task resumes running when it should remain frozen */

The existing !frozen(p) check in __thaw_task makes the
WARN_ON_ONCE(freezing(p)) warning redundant. Removing this warning enables
reverting the commit cff5f49d43 ("cgroup_freezer: cgroup_freezing: Check
if not frozen") to resolve the issue.

The warning has been removed in the previous patch. This patch revert the
commit cff5f49d43 ("cgroup_freezer: cgroup_freezing: Check if not
frozen") to complete the fix.

Fixes: cff5f49d43 ("cgroup_freezer: cgroup_freezing: Check if not frozen")
Reported-by: Zhong Jiawei<zhongjiawei1@huawei.com>
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2025-07-24 08:51:53 +02:00
..
cgroup-internal.h cgroup: Make operations on the cgroup root_list RCU safe 2024-08-19 06:00:06 +02:00
cgroup-v1.c kernfs: Convert kernfs_path_from_node_locked() from strlcpy() to strscpy() 2024-08-03 08:48:54 +02:00
cgroup.c cgroup: Fix compilation issue due to cgroup_mutex not being exported 2025-06-04 14:40:01 +02:00
cpuset.c cgroup/cpuset: Prevent UAF in proc_cpuset_show() 2024-08-03 08:48:54 +02:00
debug.c kernel: cgroup: fix misuse of %x 2019-05-06 08:47:48 -07:00
freezer.c cgroup: cleanup comments 2022-03-13 19:19:27 -10:00
legacy_freezer.c Revert "cgroup_freezer: cgroup_freezing: Check if not frozen" 2025-07-24 08:51:53 +02:00
Makefile cgroup: Add misc cgroup controller 2021-04-04 13:34:46 -04:00
misc.c misc_cgroup: remove error log to avoid log flood 2021-09-20 07:35:38 -10:00
namespace.c cgroup:namespace: Remove unused cgroup_namespaces_init() 2023-09-13 09:42:56 +02:00
pids.c cgroup: add pids.peak interface for pids controller 2022-09-04 09:26:51 -10:00
rdma.c cgroup: fix spelling mistakes 2021-05-24 12:45:26 -04:00
rstat.c cgroup: Remove steal time from usage_usec 2025-02-21 13:49:57 +01:00