INFO: task syz.1.763:8651 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.763       state:D stack:24840 pid:8651  tgid:8650  ppid:5840   task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_timeout+0x9a/0x270
 wait_for_completion+0x2bf/0x5d0
 __flush_workqueue+0x6f7/0x14b0
 nbd_disconnect_and_put+0x9e/0x2a0
 nbd_genl_disconnect+0x485/0x570
 genl_family_rcv_msg_doit+0x215/0x300
 genl_rcv_msg+0x60e/0x790
 netlink_rcv_skb+0x208/0x470
 genl_rcv+0x28/0x40
 netlink_unicast+0x82f/0x9e0
 netlink_sendmsg+0x805/0xb30
 __sock_sendmsg+0x21c/0x270
 ____sys_sendmsg+0x505/0x830
 ___sys_sendmsg+0x21f/0x2a0
 __x64_sys_sendmsg+0x19b/0x260
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f62d958ebe9
RSP: 002b:00007f62d77f6038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f62d97b5fa0 RCX: 00007f62d958ebe9
RDX: 00000000000000c0 RSI: 0000200000000280 RDI: 0000000000000006
RBP: 00007f62d9611e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f62d97b6038 R14: 00007f62d97b5fa0 R15: 00007fff609bf968
 </TASK>
INFO: task syz.1.763:8653 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.763       state:D stack:28616 pid:8653  tgid:8650  ppid:5840   task_flags:0x400040 flags:0x00004004
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7e6/0x1360
 genl_rcv_msg+0x10d/0x790
 netlink_rcv_skb+0x208/0x470
 genl_rcv+0x28/0x40
 netlink_unicast+0x82f/0x9e0
 netlink_sendmsg+0x805/0xb30
 __sock_sendmsg+0x21c/0x270
 __sys_sendto+0x3bd/0x520
 __x64_sys_sendto+0xde/0x100
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f62d9590a7c
RSP: 002b:00007f62d77d3ec0 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f62d77d3fc0 RCX: 00007f62d9590a7c
RDX: 0000000000000020 RSI: 00007f62d77d4010 RDI: 0000000000000007
RBP: 0000000000000000 R08: 00007f62d77d3f14 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000007
R13: 00007f62d77d3f68 R14: 00007f62d77d4010 R15: 0000000000000000
 </TASK>
INFO: task syz.0.766:8665 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.766       state:D stack:26056 pid:8665  tgid:8664  ppid:5845   task_flags:0x400040 flags:0x00004004
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7e6/0x1360
 genl_rcv_msg+0x10d/0x790
 netlink_rcv_skb+0x208/0x470
 genl_rcv+0x28/0x40
 netlink_unicast+0x82f/0x9e0
 netlink_sendmsg+0x805/0xb30
 __sock_sendmsg+0x21c/0x270
 __sys_sendto+0x3bd/0x520
 __x64_sys_sendto+0xde/0x100
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f30a5b90a7c
RSP: 002b:00007f30a6a8aec0 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f30a6a8afc0 RCX: 00007f30a5b90a7c
RDX: 0000000000000020 RSI: 00007f30a6a8b010 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007f30a6a8af14 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003
R13: 00007f30a6a8af68 R14: 00007f30a6a8b010 R15: 0000000000000000
 </TASK>
INFO: task syz.2.768:8741 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.768       state:D stack:28328 pid:8741  tgid:8740  ppid:5849   task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7e6/0x1360
 genl_rcv_msg+0x10d/0x790
 netlink_rcv_skb+0x208/0x470
 genl_rcv+0x28/0x40
 netlink_unicast+0x82f/0x9e0
 netlink_sendmsg+0x805/0xb30
 __sock_sendmsg+0x21c/0x270
 __sys_sendto+0x3bd/0x520
 __x64_sys_sendto+0xde/0x100
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb2f2f90a7c
RSP: 002b:00007fb2f3e59ec0 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007fb2f3e59fc0 RCX: 00007fb2f2f90a7c
RDX: 000000000000001c RSI: 00007fb2f3e5a010 RDI: 0000000000000006
RBP: 0000000000000000 R08: 00007fb2f3e59f14 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000006
R13: 00007fb2f3e59f68 R14: 00007fb2f3e5a010 R15: 0000000000000000
 </TASK>
INFO: task syz.2.768:8742 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.768       state:D stack:28616 pid:8742  tgid:8740  ppid:5849   task_flags:0x400040 flags:0x00004004
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7e6/0x1360
 genl_rcv_msg+0x10d/0x790
 netlink_rcv_skb+0x208/0x470
 genl_rcv+0x28/0x40
 netlink_unicast+0x82f/0x9e0
 netlink_sendmsg+0x805/0xb30
 __sock_sendmsg+0x21c/0x270
 __sys_sendto+0x3bd/0x520
 __x64_sys_sendto+0xde/0x100
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb2f2f90a7c
RSP: 002b:00007fb2f3e38ec0 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007fb2f3e38fc0 RCX: 00007fb2f2f90a7c
RDX: 000000000000001c RSI: 00007fb2f3e39010 RDI: 0000000000000006
RBP: 0000000000000000 R08: 00007fb2f3e38f14 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000006
R13: 00007fb2f3e38f68 R14: 00007fb2f3e39010 R15: 0000000000000000
 </TASK>
INFO: task syz.2.768:8743 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.768       state:D stack:27736 pid:8743  tgid:8740  ppid:5849   task_flags:0x400040 flags:0x00004004
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7e6/0x1360
 genl_rcv_msg+0x10d/0x790
 netlink_rcv_skb+0x208/0x470
 genl_rcv+0x28/0x40
 netlink_unicast+0x82f/0x9e0
 netlink_sendmsg+0x805/0xb30
 __sock_sendmsg+0x21c/0x270
 __sys_sendto+0x3bd/0x520
 __x64_sys_sendto+0xde/0x100
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb2f2f90a7c
RSP: 002b:00007fb2f3e17ec0 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007fb2f3e17fc0 RCX: 00007fb2f2f90a7c
RDX: 000000000000001c RSI: 00007fb2f3e18010 RDI: 0000000000000006
RBP: 0000000000000000 R08: 00007fb2f3e17f14 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000006
R13: 00007fb2f3e17f68 R14: 00007fb2f3e18010 R15: 0000000000000000
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/34:
 #0: ffffffff8e139ea0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by kworker/u13:0/56:
 #0: ffff8880203ad148 ((wq_completion)nbd0-recv){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc900007efbc0 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
2 locks held by getty/5669:
 #0: ffff88810a8db0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900029032f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400
3 locks held by syz.1.763/8651:
 #0: ffffffff8f59d230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8f59d048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10d/0x790
 #2: ffff8880203a9230 (&nbd->config_lock){+.+.}-{4:4}, at: nbd_disconnect_and_put+0x2f/0x2a0
2 locks held by syz.1.763/8653:
 #0: ffffffff8f59d230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8f59d048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10d/0x790
2 locks held by syz.0.766/8665:
 #0: ffffffff8f59d230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8f59d048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10d/0x790
2 locks held by syz.2.768/8741:
 #0: ffffffff8f59d230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8f59d048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10d/0x790
2 locks held by syz.2.768/8742:
 #0: ffffffff8f59d230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8f59d048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10d/0x790
2 locks held by syz.2.768/8743:
 #0: ffffffff8f59d230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8f59d048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10d/0x790
2 locks held by syz-executor/8753:
 #0: ffffffff8f59d230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8f59d048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10d/0x790
2 locks held by syz-executor/8764:
 #0: ffffffff8f59d230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8f59d048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10d/0x790
2 locks held by syz-executor/8767:
 #0: ffffffff8f59d230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8f59d048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10d/0x790
2 locks held by syz-executor/8783:
 #0: ffffffff8f59d230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8f59d048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10d/0x790
2 locks held by syz-executor/8795:
 #0: ffffffff8f59d230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8f59d048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10d/0x790
2 locks held by syz-executor/8797:
 #0: ffffffff8f59d230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8f59d048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10d/0x790
2 locks held by syz-executor/8819:
 #0: ffffffff8f59d230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8f59d048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10d/0x790
2 locks held by syz-executor/8830:
 #0: ffffffff8f59d230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8f59d048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10d/0x790
2 locks held by syz-executor/8832:
 #0: ffffffff8f59d230 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8f59d048 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10d/0x790

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

NMI backtrace for cpu 1
CPU: 1 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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 0 Comm: swapper/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
RIP: 0010:pv_native_safe_halt+0x13/0x20
Code: 13 e8 02 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa eb 07 0f 00 2d f3 d6 0e 00 f3 0f 1e fa fb f4 <c3> cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffffff8de07d80 EFLAGS: 00000282
RAX: 0f8195f061857e00 RBX: ffffffff819683a8 RCX: 0f8195f061857e00
RDX: 0000000000000001 RSI: ffffffff8d9b69f6 RDI: ffffffff8be33300
RBP: ffffffff8de07eb8 R08: ffff88804b032f9b R09: 1ffff110096065f3
R10: dffffc0000000000 R11: ffffed10096065f4 R12: ffffffff8fa37e30
R13: 0000000000000000 R14: 0000000000000000 R15: 1ffffffff1bd2a20
FS:  0000000000000000(0000) GS:ffff8880b861c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055cd61cf52a8 CR3: 00000000285e0000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 default_idle+0x13/0x20
 default_idle_call+0x74/0xb0
 do_idle+0x1e8/0x510
 cpu_startup_entry+0x44/0x60
 rest_init+0x2de/0x300
 start_kernel+0x3a9/0x410
 x86_64_start_reservations+0x24/0x30
 x86_64_start_kernel+0x143/0x1c0
 common_startup_64+0x13e/0x147
 </TASK>
