From: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
The commit 4f7e7236435c ("cgroup: Fix threadgroup_rwsem <-> cpus_read_lock()
deadlock") fixed the deadlock between cgroup_threadgroup_rwsem and
cpus_read_lock() by introducing cgroup_attach_{lock,unlock}() and removing
cpus_read_{lock,unlock}() from cpuset_attach(). But cgroup_transfer_tasks()
was missed and not handled, which will cause th following warning:
WARNING: CPU: 0 PID: 589 at kernel/cpu.c:526 lockdep_assert_cpus_held+0x32/0x40
CPU: 0 PID: 589 Comm: kworker/1:4 Not tainted 6.4.0-rc2-next-20230517 #50
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014
Workqueue: events cpuset_hotplug_workfn
RIP: 0010:lockdep_assert_cpus_held+0x32/0x40
<...>
Call Trace:
<TASK>
cpuset_attach+0x40/0x240
cgroup_migrate_execute+0x452/0x5e0
? _raw_spin_unlock_irq+0x28/0x40
cgroup_transfer_tasks+0x1f3/0x360
? find_held_lock+0x32/0x90
? cpuset_hotplug_workfn+0xc81/0xed0
cpuset_hotplug_workfn+0xcb1/0xed0
? process_one_work+0x248/0x5b0
process_one_work+0x2b9/0x5b0
worker_thread+0x56/0x3b0
? process_one_work+0x5b0/0x5b0
kthread+0xf1/0x120
? kthread_complete_and_exit+0x20/0x20
ret_from_fork+0x1f/0x30
</TASK>
So just use the cgroup_attach_{lock,unlock}() helper to fix it.
Fixes: 4f7e7236435c ("cgroup: Fix threadgroup_rwsem <-> cpus_read_lock() deadlock")
Reported-by: Zhao Gongyi <zhaogongyi@xxxxxxxxxxxxx>
Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
---
kernel/cgroup/cgroup-v1.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
index aeef06c465ef..5407241dbb45 100644
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -108,7 +108,7 @@ int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
cgroup_lock();
- percpu_down_write(&cgroup_threadgroup_rwsem);
+ cgroup_attach_lock(true);
/* all tasks in @from are being moved, all csets are source */
spin_lock_irq(&css_set_lock);
@@ -144,7 +144,7 @@ int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
} while (task && !ret);
out_err:
cgroup_migrate_finish(&mgctx);
- percpu_up_write(&cgroup_threadgroup_rwsem);
+ cgroup_attach_unlock(true);
cgroup_unlock();
return ret;
}
--
2.30.2
