INFO: task syz.1.4640:16306 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.4640      state:D stack:25392 pid:16306 tgid:16305 ppid:5596   task_flags:0x480140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17db/0x58f0
 schedule+0x164/0x2b0
 blk_mq_freeze_queue_wait+0x101/0x180
 queue_limits_commit_update_frozen+0x55/0xd0
 nbd_set_size+0x4c5/0x7d0
 nbd_genl_reconfigure+0x7e1/0x1040
 genl_family_rcv_msg_doit+0x233/0x340
 genl_rcv_msg+0x614/0x7a0
 netlink_rcv_skb+0x226/0x4a0
 genl_rcv+0x28/0x40
 netlink_unicast+0x7bd/0x940
 netlink_sendmsg+0x813/0xb40
 sock_sendmsg_nosec+0x14e/0x190
 ____sys_sendmsg+0x54e/0x850
 ___sys_sendmsg+0x2a5/0x360
 __x64_sys_sendmsg+0x1b1/0x290
 do_syscall_64+0x166/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f83ad59e199
RSP: 002b:00007f83ae4b1028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f83ad825fa0 RCX: 00007f83ad59e199
RDX: 0000000004000080 RSI: 00002000000005c0 RDI: 0000000000000004
RBP: 00007f83ad6350b8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f83ad826038 R14: 00007f83ad825fa0 R15: 00007fff97249798
 </TASK>
INFO: task syz.0.4642:16313 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.4642      state:D stack:25856 pid:16313 tgid:16312 ppid:5590   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17db/0x58f0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7c1/0x1550
 genl_rcv_msg+0x10b/0x7a0
 netlink_rcv_skb+0x226/0x4a0
 genl_rcv+0x28/0x40
 netlink_unicast+0x7bd/0x940
 netlink_sendmsg+0x813/0xb40
 sock_sendmsg_nosec+0x14e/0x190
 ____sys_sendmsg+0x54e/0x850
 ___sys_sendmsg+0x2a5/0x360
 __x64_sys_sendmsg+0x1b1/0x290
 do_syscall_64+0x166/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9c24d9e199
RSP: 002b:00007f9c25c42028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f9c25025fa0 RCX: 00007f9c24d9e199
RDX: 0000000000000000 RSI: 0000200000000240 RDI: 0000000000000003
RBP: 00007f9c24e350b8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9c25026038 R14: 00007f9c25025fa0 R15: 00007fffbc83a9c8
 </TASK>
INFO: task syz.2.4645:16320 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.4645      state:D stack:27904 pid:16320 tgid:16319 ppid:5591   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17db/0x58f0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7c1/0x1550
 genl_rcv_msg+0x10b/0x7a0
 netlink_rcv_skb+0x226/0x4a0
 genl_rcv+0x28/0x40
 netlink_unicast+0x7bd/0x940
 netlink_sendmsg+0x813/0xb40
 sock_sendmsg_nosec+0x14e/0x190
 __sys_sendto+0x408/0x5a0
 __x64_sys_sendto+0xde/0x100
 do_syscall_64+0x166/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe363b5e9ce
RSP: 002b:00007fe364b16e88 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007fe364b186c0 RCX: 00007fe363b5e9ce
RDX: 0000000000000020 RSI: 00007fe364b17000 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007fe364b16f04 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 00007fe364b16f58 R14: 00007fe364b17000 R15: 0000000000000000
 </TASK>

Showing all locks held in the system:
locks held by khungtaskd/36: 1, last CPU#0:
 #0: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
locks held by getty/5423: 2, on CPU#1:
 #0: ffff88816d1a20a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900034762e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360
locks held by udevd/7666: 1, on CPU#1:
 #0: ffff88816c420350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xde/0xd70
locks held by syz.1.4640/16306: 6, on CPU#0:
 #0: ffffffff902b91e8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff902b9020 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0
 #2: ffff88816c136260 (&nbd->config_lock){+.+.}-{4:4}, at: nbd_genl_reconfigure+0x4a6/0x1040
 #3: ffff88816c413e78 (&q->limits_lock){+.+.}-{4:4}, at: nbd_set_size+0x284/0x7d0
 #4: ffff88816c413840 (&q->q_usage_counter(io)#50){++++}-{0:0}, at: queue_limits_commit_update_frozen+0x55/0xd0
 #5: ffff88816c413878 (&q->q_usage_counter(queue)#34){+.+.}-{0:0}, at: queue_limits_commit_update_frozen+0x55/0xd0
locks held by syz.0.4642/16313: 2, on CPU#1:
 #0: ffffffff902b91e8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff902b9020 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0
locks held by syz.2.4645/16320: 2, on CPU#0:
 #0: ffffffff902b91e8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff902b9020 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0
locks held by syz-executor/16327: 2, on CPU#1:
 #0: ffffffff902b91e8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff902b9020 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0
locks held by syz-executor/16331: 2, on CPU#0:
 #0: ffffffff902b91e8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff902b9020 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0
locks held by syz-executor/16333: 2, on CPU#1:
 #0: ffffffff902b91e8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff902b9020 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0
locks held by syz-executor/16381: 2, on CPU#1:
 #0: ffffffff902b91e8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff902b9020 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0
locks held by syz-executor/16385: 2, on CPU#0:
 #0: ffffffff902b91e8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff902b9020 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0
locks held by syz-executor/16387: 2, on CPU#1:
 #0: ffffffff902b91e8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff902b9020 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0
locks held by syz-executor/16440: 2, on CPU#0:
 #0: ffffffff902b91e8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff902b9020 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0
locks held by syz-executor/16442: 2, on CPU#0:
 #0: ffffffff902b91e8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff902b9020 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0
locks held by syz-executor/16447: 2, on CPU#1:
 #0: ffffffff902b91e8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff902b9020 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 36 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+0xe8/0x150
 nmi_cpu_backtrace+0x274/0x2d0
 nmi_trigger_cpumask_backtrace+0x17d/0x390
 sys_info+0x135/0x170
 watchdog+0xfd7/0x1030
 kthread+0x38b/0x480
 ret_from_fork+0x514/0xb70
 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: 0 Comm: swapper/1 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+0xf/0x20
Code: 3b 87 02 c3 cc cc cc cc 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 d3 61 23 00 fb f4 <e9> 8c 08 03 00 cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90
RSP: 0018:ffffc900001a7e40 EFLAGS: 00000206
RAX: 0000000000197a27 RBX: ffffffff819bdc20 RCX: 8000000000000001
RDX: 0000000000000001 RSI: ffffffff8e405b24 RDI: ffffffff8c6dad80
RBP: ffffc900001a7f10 R08: ffff88823c633a1b R09: 1ffff110478c6743
R10: dffffc0000000000 R11: ffffed10478c6744 R12: 0000000000000000
R13: 1ffff1102c097000 R14: 1ffff92000034fd0 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8882a8cda000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff7537eff8 CR3: 000000000eb48000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 default_idle+0x9/0x20
 default_idle_call+0x72/0xb0
 do_idle+0x2e0/0x540
 cpu_startup_entry+0x43/0x60
 start_secondary+0x101/0x110
 common_startup_64+0x13e/0x157
 </TASK>
