INFO: task syz.1.365:8644 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.365       state:D stack:0     pid:8644  tgid:8639  ppid:6570   task_flags:0x400140 flags:0x00000001
Call trace:
 __switch_to+0x418/0x87c arch/arm64/kernel/process.c:741 (T)
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x1250/0x2a7c kernel/sched/core.c:6863
 __schedule_loop kernel/sched/core.c:6945 [inline]
 schedule+0xb4/0x230 kernel/sched/core.c:6960
 schedule_preempt_disabled+0x18/0x2c kernel/sched/core.c:7017
 __mutex_lock_common+0xd04/0x2678 kernel/locking/mutex.c:692
 __mutex_lock kernel/locking/mutex.c:776 [inline]
 mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:828
 nfsd_nl_listener_set_doit+0x10c/0x1294 fs/nfsd/nfsctl.c:1880
 genl_family_rcv_msg_doit+0x1d8/0x2bc net/netlink/genetlink.c:1115
 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
 genl_rcv_msg+0x450/0x624 net/netlink/genetlink.c:1210
 netlink_rcv_skb+0x220/0x3fc net/netlink/af_netlink.c:2550
 genl_rcv+0x38/0x50 net/netlink/genetlink.c:1219
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x694/0x8c4 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x648/0x930 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 ____sys_sendmsg+0x490/0x7c4 net/socket.c:2592
 ___sys_sendmsg+0x204/0x278 net/socket.c:2646
 __sys_sendmsg net/socket.c:2678 [inline]
 __do_sys_sendmsg net/socket.c:2683 [inline]
 __se_sys_sendmsg net/socket.c:2681 [inline]
 __arm64_sys_sendmsg+0x184/0x238 net/socket.c:2681
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x5c/0x26c arch/arm64/kernel/entry-common.c:724
 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596

Showing all locks held in the system:
1 lock held by khungtaskd/32:
 #0: ffff80008fa5b520 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire+0x4/0x48 include/linux/rcupdate.h:330
2 locks held by pr/ttyAMA-1/43:
2 locks held by kworker/u8:19/5260:
2 locks held by getty/6353:
 #0: ffff0000cdf0c0a0 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x3c/0x4c drivers/tty/tty_ldsem.c:340
 #1: ffff800099f1e2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x34c/0xfc8 drivers/tty/n_tty.c:2211
4 locks held by kworker/1:6/6641:
 #0: ffff0000c0029948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x63c/0x1558 kernel/workqueue.c:3231
 #1: ffff8000a4497be0 ((work_completion)(&helper->damage_work)){+.+.}-{0:0}, at: process_one_work+0x6d0/0x1558 kernel/workqueue.c:3231
 #2: ffff0000ca6e8a80 (&helper->lock){+.+.}-{4:4}, at: drm_fb_helper_fb_dirty drivers/gpu/drm/drm_fb_helper.c:333 [inline]
 #2: ffff0000ca6e8a80 (&helper->lock){+.+.}-{4:4}, at: drm_fb_helper_damage_work+0xa8/0x568 drivers/gpu/drm/drm_fb_helper.c:369
 #3: ffff0000ca6d6128 (&dev->master_mutex){+.+.}-{4:4}, at: drm_master_internal_acquire+0x24/0x78 drivers/gpu/drm/drm_auth.c:435
2 locks held by syz.1.365/8642:
 #0: ffff800092b49830 (cb_lock){++++}-{4:4}, at: genl_rcv+0x28/0x50 net/netlink/genetlink.c:1218
 #1: ffff80008fd3fa08 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x10c/0x1294 fs/nfsd/nfsctl.c:1880
2 locks held by syz.1.365/8644:
 #0: ffff800092b49830 (cb_lock){++++}-{4:4}, at: genl_rcv+0x28/0x50 net/netlink/genetlink.c:1218
 #1: ffff80008fd3fa08 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x10c/0x1294 fs/nfsd/nfsctl.c:1880

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