INFO: task syz.1.7006:21951 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.7006      state:D stack:27208 pid:21951 tgid:21950 ppid:5614   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17b4/0x5680
 schedule+0x164/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7f7/0x1550
 nfsd_nl_listener_set_doit+0x141/0x1670
 genl_family_rcv_msg_doit+0x22a/0x330
 genl_rcv_msg+0x61c/0x7a0
 netlink_rcv_skb+0x232/0x4b0
 genl_rcv+0x28/0x40
 netlink_unicast+0x75c/0x8e0
 netlink_sendmsg+0x813/0xb40
 ____sys_sendmsg+0x972/0x9f0
 ___sys_sendmsg+0x2a5/0x360
 __x64_sys_sendmsg+0x1bd/0x2a0
 do_syscall_64+0x15f/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f641f79cdd9
RSP: 002b:00007f642059f028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f641fa15fa0 RCX: 00007f641f79cdd9
RDX: 0000000004000040 RSI: 0000200000000100 RDI: 0000000000000003
RBP: 00007f641f832d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f641fa16038 R14: 00007f641fa15fa0 R15: 00007ffda11c0838
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/34:
 #0: ffffffff8e95cd60 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5437:
 #0: ffff88810f20e0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900034732e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13a0
3 locks held by kworker/1:9/9511:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860
 #1: ffffc90004c1fc40 (free_ipc_work){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860
 #2: ffffffff8e963068 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2d0/0x770
2 locks held by syz.0.4177/15244:
 #0: ffffffff8fe3f7c8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8ec8aca0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x141/0x1670
2 locks held by syz.1.7006/21951:
 #0: ffffffff8fe3f7c8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8ec8aca0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x141/0x1670
2 locks held by syz.3.9810/28431:
 #0: ffffffff8fe3f7c8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40
 #1: ffffffff8ec8aca0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_version_get_doit+0x17c/0xc40
1 lock held by syz.2.10328/29702:

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

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+0xe8/0x150
 nmi_cpu_backtrace+0x274/0x2d0
 nmi_trigger_cpumask_backtrace+0x17a/0x300
 sys_info+0x135/0x170
 watchdog+0xfd3/0x1030
 kthread+0x388/0x470
 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: 798 Comm: kworker/1:2 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 drain_vmap_area_work
RIP: 0010:check_preemption_disabled+0x22/0xe0
Code: 90 90 90 90 90 90 90 90 55 41 57 41 56 53 65 8b 05 b7 cf 8f 07 65 8b 0d ac cf 8f 07 f7 c1 ff ff ff 7f 74 0c 5b 41 5e 41 5f 5d <e9> 09 d7 02 00 cc 9c 59 f7 c1 00 02 00 00 74 ea 65 4c 8b 3d 5e cf
RSP: 0018:ffffc9000505f620 EFLAGS: 00000046
RAX: 0000000000000001 RBX: 00000000ffffffff RCX: 0000000000000046
RDX: 0000000000000000 RSI: ffffffff8dfc456b RDI: ffffffff8c28ade0
RBP: 00000000ffffffff R08: ffffffff823c872a R09: ffffffff8e95cd60
R10: dffffc0000000000 R11: ffffed102142eb88 R12: 0000000000000246
R13: ffff88816c300000 R14: ffffffff8e95cd60 R15: 0000000000001000
FS:  0000000000000000(0000) GS:ffff8882a9287000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe442487e20 CR3: 0000000112f6c000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 lock_is_held_type+0x5a/0x150
 page_ext_lookup+0xe7/0x180
 __page_table_check_zero+0x135/0x3e0
 __free_frozen_pages+0xbd7/0xd30
 kasan_depopulate_vmalloc_pte+0x6d/0x90
 __apply_to_page_range+0xbdc/0x1420
 __kasan_release_vmalloc+0xa2/0xd0
 purge_vmap_node+0x220/0x960
 __purge_vmap_area_lazy+0x779/0xb40
 drain_vmap_area_work+0x27/0x40
 process_scheduled_works+0xb5d/0x1860
 worker_thread+0xa53/0xfc0
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
