INFO: task syz.7.5402:18821 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.5402      state:D stack:27432 pid:18821 tgid:18819 ppid:12098  task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17db/0x58f0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7c1/0x1550
 nfsd4_write_time+0xb1/0x6c0
 nfsctl_transaction_write+0x10f/0x160
 vfs_write+0x296/0xba0
 ksys_write+0x150/0x270
 do_syscall_64+0x166/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd85ab9e159
RSP: 002b:00007fd85b9a8028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fd85ae26090 RCX: 00007fd85ab9e159
RDX: 0000000000000003 RSI: 0000200000000700 RDI: 0000000000000005
RBP: 00007fd85ac3506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd85ae26128 R14: 00007fd85ae26090 R15: 00007ffef8ad1258
 </TASK>
INFO: task syz.7.5402:18824 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.5402      state:D stack:27432 pid:18824 tgid:18819 ppid:12098  task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17db/0x58f0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7c1/0x1550
 write_threads+0x3b1/0x610
 nfsctl_transaction_write+0x10f/0x160
 vfs_write+0x296/0xba0
 ksys_write+0x150/0x270
 do_syscall_64+0x166/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd85ab9e159
RSP: 002b:00007fd85b987028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fd85ae26180 RCX: 00007fd85ab9e159
RDX: 0000000000000002 RSI: 0000200000000900 RDI: 0000000000000006
RBP: 00007fd85ac3506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd85ae26218 R14: 00007fd85ae26180 R15: 00007ffef8ad1258
 </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/5425: 2, on CPU#0:
 #0: ffff8881184b20a0 (&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 syz.7.5402/18820: 3, on CPU#0:
 #0: ffff88803235bcf0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320
 #1: ffff888103aa0460 (sb_writers#39){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0
 #2: ffffffff8f09f860 (nfsd_mutex){+.+.}-{4:4}, at: write_ports+0xb5/0xd10
locks held by syz.7.5402/18821: 3, on CPU#0:
 #0: ffff8880323486f0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320
 #1: ffff888103aa0460 (sb_writers#39){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0
 #2: ffffffff8f09f860 (nfsd_mutex){+.+.}-{4:4}, at: nfsd4_write_time+0xb1/0x6c0
locks held by syz.7.5402/18824: 3, on CPU#0:
 #0: ffff8880321f44f0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320
 #1: ffff888103aa0460 (sb_writers#39){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0
 #2: ffffffff8f09f860 (nfsd_mutex){+.+.}-{4:4}, at: write_threads+0x3b1/0x610
locks held by syz.5.7213/23134: 1, on CPU#0:
 #0: ffff88810d4e8340 (&mm->mmap_lock){++++}-{4:4}, at: vm_mmap_pgoff+0x1dd/0x4e0
locks held by syz.5.7213/23138: 3, last CPU#0:
 #0: ffff88810d4e8340 (&mm->mmap_lock){++++}-{4:4}, at: __mm_populate+0x182/0x390
 #1: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: do_pte_missing+0x140c/0x34b0
 #2: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: filemap_map_pages+0x1d1/0x2170

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 36 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
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>
