INFO: task kworker/u4:6:2657 blocked for more than 143 seconds.
      Not tainted 5.15.120-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:6    state:D stack:24640 pid: 2657 ppid:     2 flags:0x00004000
Workqueue: events_unbound io_ring_exit_work
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5026 [inline]
 __schedule+0x12c4/0x4590 kernel/sched/core.c:6372
 schedule+0x11b/0x1f0 kernel/sched/core.c:6455
 schedule_timeout+0xac/0x300 kernel/time/timer.c:1860
 do_wait_for_common+0x2d9/0x480 kernel/sched/completion.c:85
 __wait_for_common kernel/sched/completion.c:106 [inline]
 wait_for_common kernel/sched/completion.c:117 [inline]
 wait_for_completion+0x48/0x60 kernel/sched/completion.c:138
 io_ring_exit_work+0x6a9/0x1330 io_uring/io_uring.c:9725
 process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2307
 worker_thread+0xaca/0x1280 kernel/workqueue.c:2454
 kthread+0x3f6/0x4f0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
 </TASK>

Showing all locks held in the system:
4 locks held by kworker/u4:0/9:
1 lock held by khungtaskd/27:
 #0: ffffffff8c91e6a0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by kworker/u4:6/2657:
 #0: ffff888011c69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2280
 #1: ffffc9000bac7d20 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2282
1 lock held by udevd/2964:
2 locks held by getty/3259:
 #0: ffff88814b10d098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc900020a32e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6af/0x1da0 drivers/tty/n_tty.c:2147
2 locks held by kworker/1:4/3524:
 #0: ffff888011c66538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2280
 #1: ffffc90002eefd20 ((work_completion)(&rew.rew_work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2282
2 locks held by kworker/u4:11/4974:
 #0: ffff888011c69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2280
 #1: ffffc90004e97d20 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2282
1 lock held by udevd/9570:
 #0: ffff8880b9b396d8 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:475
1 lock held by syz-executor.2/15686:
 #0: ffffffff8c922be8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline]
 #0: ffffffff8c922be8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x350/0x740 kernel/rcu/tree_exp.h:842
1 lock held by syz-executor.0/15683:
 #0: ffffffff8c922be8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:290 [inline]
 #0: ffffffff8c922be8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x280/0x740 kernel/rcu/tree_exp.h:842

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

NMI backtrace for cpu 1
CPU: 1 PID: 27 Comm: khungtaskd Not tainted 5.15.120-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 nmi_cpu_backtrace+0x46a/0x4a0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x181/0x2a0 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:210 [inline]
 watchdog+0xe72/0xeb0 kernel/hung_task.c:295
 kthread+0x3f6/0x4f0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 15701 Comm: syz-executor.1 Not tainted 5.15.120-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023
RIP: 0010:io_serial_in+0x72/0xb0 drivers/tty/serial/8250/8250_port.c:461
Code: 24 e6 07 fd 89 e9 41 d3 e6 48 83 c3 40 48 89 d8 48 c1 e8 03 42 80 3c 38 00 74 08 48 89 df e8 e5 53 51 fd 44 03 33 44 89 f2 ec <0f> b6 c0 5b 41 5e 41 5f 5d c3 89 e9 80 e1 07 38 c1 7c ad 48 89 ef
RSP: 0018:ffffc900066af290 EFLAGS: 00000002
RAX: 1ffffffff22de620 RBX: ffffffff916f3240 RCX: 0000000000000000
RDX: 00000000000003fd RSI: 0000000000000000 RDI: 0000000000000020
RBP: 0000000000000000 R08: ffffffff84781a72 R09: 0000000000000003
R10: ffffffffffffffff R11: dffffc0000000001 R12: 1ffffffff22de695
R13: ffffffff916f3200 R14: 00000000000003fd R15: dffffc0000000000
FS:  00007f401a06f6c0(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000001e9cd000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 serial_in drivers/tty/serial/8250/8250.h:117 [inline]
 wait_for_xmitr+0xec/0x260 drivers/tty/serial/8250/8250_port.c:2086
 serial8250_console_putchar+0x19/0x50 drivers/tty/serial/8250/8250_port.c:3322
 uart_console_write+0xa9/0x100 drivers/tty/serial/serial_core.c:1971
 serial8250_console_write+0xc8e/0x1180 drivers/tty/serial/8250/8250_port.c:3399
 console_unlock+0xced/0x12b0 kernel/printk/printk.c:2734
 vprintk_emit+0xba/0x150 kernel/printk/printk.c:2268
 _printk+0xd1/0x111 kernel/printk/printk.c:2289
 fscache_print_cookie+0x2b9/0x3f0 fs/fscache/cookie.c:62
 fscache_hash_cookie+0x7ac/0x990 fs/fscache/cookie.c:231
 __fscache_acquire_cookie+0x1a8/0x550 fs/fscache/cookie.c:306
 fscache_acquire_cookie include/linux/fscache.h:334 [inline]
 v9fs_cache_session_get_cookie+0x1a4/0x240 fs/9p/cache.c:60
 v9fs_session_init+0x1567/0x1910 fs/9p/v9fs.c:473
 v9fs_mount+0x72/0x860 fs/9p/vfs_super.c:126
 legacy_get_tree+0xeb/0x180 fs/fs_context.c:610
 vfs_get_tree+0x88/0x270 fs/super.c:1508
 do_new_mount+0x28b/0xae0 fs/namespace.c:2994
 do_mount fs/namespace.c:3337 [inline]
 __do_sys_mount fs/namespace.c:3545 [inline]
 __se_sys_mount+0x2d5/0x3c0 fs/namespace.c:3522
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f401acedb29
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f401a06f0c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f401ae0cf80 RCX: 00007f401acedb29
RDX: 0000000020000180 RSI: 0000000020000000 RDI: 0000000000000000
RBP: 00007f401ad3947a R08: 00000000200001c0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f401ae0cf80 R15: 00007ffd3149b8b8
 </TASK>