In the Linux kernel, the following vulnerability has been resolved:
cgroup: split cgroup_destroy_wq into 3 workqueues
A hung task can occur during [1] LTP cgroup testing when repeatedly
mounting/unmounting perf_event and net_prio controllers with
systemd.unified_cgroup_hierarchy=1. The hang manifests in
cgroup_lock_and_drain_offline() during root destruction.
Related case:
cgroup_fj_function_perf_event cgroup_fj_function.sh perf_event
cgroup_fj_function_net_prio cgroup_fj_function.sh net_prio
Call Trace:
cgroup_lock_and_drain_offline+0x14c/0x1e8
cgroup_destroy_root+0x3c/0x2c0
css_free_rwork_fn+0x248/0x338
process_one_work+0x16c/0x3b8
worker_thread+0x22c/0x3b0
kthread+0xec/0x100
ret_from_fork+0x10/0x20
Root Cause:
CPU0 CPU1
mount perf_event umount net_prio
cgroup1_get_tree cgroup_kill_sb
rebind_subsystems // root destruction enqueues
// cgroup_destroy_wq
// kill all perf_event css
// one perf_event css A is dying
// css A offline enqueues cgroup_destroy_wq
// root destruction will be executed first
css_free_rwork_fn
cgroup_destroy_root
cgroup_lock_and_drain_offline
// some perf descendants are dying
// cgroup_destroy_wq max_active = 1
// waiting for css A to die
Problem scenario:
1. CPU0 mounts perf_event (rebind_subsystems)
2. CPU1 unmounts net_prio (cgroup_kill_sb), queuing root destruction work
3. A dying perf_event CSS gets queued for offline after root destruction
4. Root destruction waits for offline completion, but offline work is
blocked behind root destruction in cgroup_destroy_wq (max_active=1)
Solution:
Split cgroup_destroy_wq into three dedicated workqueues:
cgroup_offline_wq – Handles CSS offline operations
cgroup_release_wq – Manages resource release
cgroup_free_wq – Performs final memory deallocation
This separation eliminates blocking in the CSS free path while waiting for
offline operations to complete.
[1] https://github.com/linux-test-project/ltp/blob/master/runtest/controllers
References
Configurations
Configuration 1 (hide)
|
History
23 Jan 2026, 20:01
| Type | Values Removed | Values Added |
|---|---|---|
| References | () https://git.kernel.org/stable/c/05e0b03447cf215ec384210441b34b7a3b16e8b0 - Patch | |
| References | () https://git.kernel.org/stable/c/4a1e3ec28e8062cd9f339aa6a942df9c5bcb6811 - Patch | |
| References | () https://git.kernel.org/stable/c/79f919a89c9d06816dbdbbd168fa41d27411a7f9 - Patch | |
| References | () https://git.kernel.org/stable/c/993049c9b1355c78918344a6403427d53f9ee700 - Patch | |
| References | () https://git.kernel.org/stable/c/a0c896bda7077aa5005473e2c5b3c27173313b4c - Patch | |
| References | () https://git.kernel.org/stable/c/cabadd7fd15f97090f752fd22dd7f876a0dc3dc4 - Patch | |
| References | () https://git.kernel.org/stable/c/ded4d207a3209a834b6831ceec7f39b934c74802 - Patch | |
| References | () https://git.kernel.org/stable/c/f2795d1b92506e3adf52a298f7181032a1525e04 - Patch | |
| CWE | NVD-CWE-noinfo | |
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 5.5 |
| CPE | cpe:2.3:o:linux:linux_kernel:6.17:rc5:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.17:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.17:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.17:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.17:rc6:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:* |
|
| First Time |
Linux
Linux linux Kernel |
04 Oct 2025, 08:15
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2025-10-04 08:15
Updated : 2026-01-23 20:01
NVD link : CVE-2025-39953
Mitre link : CVE-2025-39953
CVE.ORG link : CVE-2025-39953
JSON object : View
Products Affected
linux
- linux_kernel
CWE