In the Linux kernel, the following vulnerability has been resolved:

tracing/timerlat: Drop interface_lock in stop_kthread()

stop_kthread() is the offline callback for "trace/osnoise:online", since
commit 5bfbcd1ee57b ("tracing/timerlat: Add interface_lock around clearing
of kthread in stop_kthread()"), the following ABBA deadlock scenario is
introduced:

T1                            | T2 [BP]               | T3 [AP]
osnoise_hotplug_workfn()      | work_for_cpu_fn()     | cpuhp_thread_fun()
                              |   _cpu_down()         |   osnoise_cpu_die()
  mutex_lock(&interface_lock) |                       |     stop_kthread()
                              |     cpus_write_lock() |       mutex_lock(&interface_lock)
  cpus_read_lock()            |     cpuhp_kick_ap()   |

As the interface_lock here in just for protecting the "kthread" field of
the osn_var, use xchg() instead to fix this issue. Also use
for_each_online_cpu() back in stop_per_cpu_kthreads() as it can take
cpu_read_lock() again.

kernel.org https://git.kernel.org/stable/c/09cb44cc3d3df7ade2cebc939d6257a2fa8afc7a [No types assigned]

kernel.org https://git.kernel.org/stable/c/a4a05ceffe8fad68b45de38fe2311bda619e76e2 [No types assigned]

kernel.org https://git.kernel.org/stable/c/b484a02c9cedf8703eff8f0756f94618004bd165 [No types assigned]

kernel.org https://git.kernel.org/stable/c/db8571a9a098086608c11a15856ff585789e67e8 [No types assigned]