CVE-2022-50149: In the Linux kernel, the following vulnerability has been resolved:  driver core: fix potential deadlock in __driver_attach  In __driver_attach function, There are also AA deadlock problem, like the commit b232b02bf3c2 ("driver core: fix deadlock in __device_attach").  stack like commit b232b02bf3c2 ("driver core: fix deadlock in __device_attach"). list below:     In __driver_attach function, The lock holding logic is as follows:     ...     __driver_attach     if (driver_allows_async_probing(drv))       device_lock(dev)      // get lock dev         async_schedule_dev(__driver_attach_async_helper, dev); // func           async_schedule_node             async_schedule_node_domain(func)               entry = kzalloc(sizeof(struct async_entry), GFP_ATOMIC);               /* when fail or work limit, sync to execute func, but                  __driver_attach_async_helper will get lock dev as                  will, which will lead to A-A deadlock.  */               if (!entry || atomic_read(&entry_count) > MAX_WORK) {                 func;               else                 queue_work_node(node, system_unbound_wq, &entry->work)       device_unlock(dev)      As above show, when it is allowed to do async probes, because of     out of memory or work limit, async work is not be allowed, to do     sync execute instead. it will lead to A-A deadlock because of     __driver_attach_async_helper getting lock dev.  Reproduce: and it can be reproduce by make the condition (if (!entry || atomic_read(&entry_count) > MAX_WORK)) untenable, like below:  [  370.785650] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [  370.787154] task:swapper/0       state:D stack:    0 pid:    1 ppid: 0 flags:0x00004000 [  370.788865] Call Trace: [  370.789374]  <TASK> [  370.789841]  __schedule+0x482/0x1050 [  370.790613]  schedule+0x92/0x1a0 [  370.791290]  schedule_preempt_disabled+0x2c/0x50 [  370.792256]  __mutex_lock.isra.0+0x757/0xec0 [  370.793158]  __mutex_lock_slowpath+0x1f/0x30 [  370.794079]  mutex_lock+0x50/0x60 [  370.794795]  __device_driver_lock+0x2f/0x70 [  370.795677]  ? driver_probe_device+0xd0/0xd0 [  370.796576]  __driver_attach_async_helper+0x1d/0xd0 [  370.797318]  ? driver_probe_device+0xd0/0xd0 [  370.797957]  async_schedule_node_domain+0xa5/0xc0 [  370.798652]  async_schedule_node+0x19/0x30 [  370.799243]  __driver_attach+0x246/0x290 [  370.799828]  ? driver_allows_async_probing+0xa0/0xa0 [  370.800548]  bus_for_each_dev+0x9d/0x130 [  370.801132]  driver_attach+0x22/0x30 [  370.801666]  bus_add_driver+0x290/0x340 [  370.802246]  driver_register+0x88/0x140 [  370.802817]  ? virtio_scsi_init+0x116/0x116 [  370.803425]  scsi_register_driver+0x1a/0x30 [  370.804057]  init_sd+0x184/0x226 [  370.804533]  do_one_initcall+0x71/0x3a0 [  370.805107]  kernel_init_freeable+0x39a/0x43a [  370.805759]  ? rest_init+0x150/0x150 [  370.806283]  kernel_init+0x26/0x230 [  370.806799]  ret_from_fork+0x1f/0x30  To fix the deadlock, move the async_schedule_dev outside device_lock, as we can see, in async_schedule_node_domain, the parameter of queue_work_node is system_unbound_wq, so it can accept concurrent operations. which will also not change the code logic, and will not lead to deadlock.