INFO: task syz.7.1296:11512 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.1296      state:D stack:24040 pid:11512 tgid:11511 ppid:11336  task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7e6/0x1350
 sync_bdevs+0x1ac/0x340
 ksys_sync+0xb9/0x150
 __ia32_sys_sync+0xe/0x20
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f16e5b8ebe9
RSP: 002b:00007f16e6ac9038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f16e5dc5fa0 RCX: 00007f16e5b8ebe9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f16e5dc5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f16e5dc6038 R14: 00007f16e5dc5fa0 R15: 00007ffd30a1b928
 </TASK>

Showing all locks held in the system:
3 locks held by kworker/u8:0/12:
1 lock held by khungtaskd/34:
 #0: ffffffff8e139f20 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5670:
 #0: ffff8880280190a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900029062f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400
5 locks held by kworker/0:3/5892:
 #0: ffff88810510f148 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc9000375fbc0 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffff8880218a2198 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4a20
 #3: ffff88803e296198 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x400
 #4: ffff88803e292160 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x400
1 lock held by udevd/5944:
 #0: ffff88802031e358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30
5 locks held by kworker/0:5/7674:
 #0: ffff88810510f148 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc90004eefbc0 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffff8880217fa198 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4a20
 #3: ffff88803a1d5198 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x400
 #4: ffff888041280160 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x400
1 lock held by syz.7.1296/11512:
 #0: ffff88802031e358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x1ac/0x340
4 locks held by kworker/1:6/13528:
 #0: ffff88810510f148 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc900032bfbc0 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffff888021812198 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4a20
 #3: ffff88811add4198 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x400
1 lock held by syz.9.1753/13658:
 #0: ffff88802031e358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x1ac/0x340
1 lock held by syz.9.1753/13659:
 #0: ffff88802031e358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x1ac/0x340
1 lock held by syz.3.1896/14379:

=============================================

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 34 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250
 nmi_cpu_backtrace+0x39e/0x3d0
 nmi_trigger_cpumask_backtrace+0x17a/0x300
 watchdog+0xf93/0xfe0
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 24 Comm: kworker/1:0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Workqueue: events drm_fb_helper_damage_work
RIP: 0010:bochs_primary_plane_helper_atomic_update+0x567/0x930
Code: 00 00 fc ff df 43 80 3c 2f 00 74 08 4c 89 f7 e8 bf 34 26 fc 4d 8b 26 4d 85 e4 74 10 e8 f2 68 c2 fb 66 41 89 9c 24 10 05 00 00 <eb> 17 e8 e2 68 c2 fb 66 b8 08 00 66 ba ce 01 66 ef 89 d8 66 ba cf
RSP: 0018:ffffc900001c72c0 EFLAGS: 00000293
RAX: ffffffff85fd450e RBX: 0000000000000000 RCX: ffff8881006a0000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900001c7450 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffc900000b9000
R13: dffffc0000000000 R14: ffff88801f70cd78 R15: 1ffff11003ee19af
FS:  0000000000000000(0000) GS:ffff8881a3c14000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32a1bff8 CR3: 0000000123cbc000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 drm_atomic_helper_commit_planes+0x60f/0xec0
 drm_atomic_helper_commit_tail+0x5d/0x520
 commit_tail+0x29a/0x3a0
 drm_atomic_helper_commit+0xa6b/0xb10
 drm_atomic_commit+0x262/0x2c0
 drm_atomic_helper_dirtyfb+0xd7b/0xee0
 drm_fbdev_shmem_helper_fb_dirty+0x160/0x2f0
 drm_fb_helper_damage_work+0x224/0x710
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30
 </TASK>
