INFO: task kworker/u4:15:8461 blocked for more than 143 seconds. Not tainted 6.4.0-rc2-next-20230515-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u4:15 state:D stack:26280 pid:8461 ppid:2 flags:0x00004000 Workqueue: events_unbound flush_to_ldisc Call Trace: context_switch kernel/sched/core.c:5343 [inline] __schedule+0x1d15/0x5790 kernel/sched/core.c:6669 schedule+0xde/0x1a0 kernel/sched/core.c:6745 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6804 __mutex_lock_common kernel/locking/mutex.c:679 [inline] __mutex_lock+0xa3b/0x1350 kernel/locking/mutex.c:747 commit_echoes+0x4c/0x210 drivers/tty/n_tty.c:765 n_tty_receive_char+0x3b7/0x5b0 drivers/tty/n_tty.c:1419 n_tty_receive_buf_standard+0x930/0x2de0 drivers/tty/n_tty.c:1588 __receive_buf drivers/tty/n_tty.c:1612 [inline] n_tty_receive_buf_common+0x3a8/0x1540 drivers/tty/n_tty.c:1710 tty_ldisc_receive_buf+0xa7/0x190 drivers/tty/tty_buffer.c:457 tty_port_default_receive_buf+0x72/0xa0 drivers/tty/tty_port.c:39 receive_buf drivers/tty/tty_buffer.c:515 [inline] flush_to_ldisc+0x218/0x700 drivers/tty/tty_buffer.c:565 process_one_work+0x99a/0x15e0 kernel/workqueue.c:2407 worker_thread+0x67d/0x10c0 kernel/workqueue.c:2554 kthread+0x344/0x440 kernel/kthread.c:379 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308 Showing all locks held in the system: 1 lock held by kthreadd/2: 2 locks held by kworker/0:0/7: #0: ffff888012470d38 ((wq_completion)events){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff888012470d38 ((wq_completion)events){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline] #0: ffff888012470d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1324 [inline] #0: ffff888012470d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:643 [inline] #0: ffff888012470d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:670 [inline] #0: ffff888012470d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x883/0x15e0 kernel/workqueue.c:2378 #1: ffffc900000c7db0 (free_ipc_work){+.+.}-{0:0}, at: process_one_work+0x8b7/0x15e0 kernel/workqueue.c:2382 3 locks held by kworker/u4:0/10: 1 lock held by rcu_tasks_kthre/13: #0: ffffffff8c798530 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x31/0xd80 kernel/rcu/tasks.h:522 1 lock held by rcu_tasks_trace/14: #0: ffffffff8c798230 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x31/0xd80 kernel/rcu/tasks.h:522 1 lock held by khungtaskd/28: #0: ffffffff8c799140 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x390 kernel/locking/lockdep.c:6559 1 lock held by khugepaged/34: #0: ffffffff8c89c248 (lock#3){+.+.}-{3:3}, at: __lru_add_drain_all+0x62/0x6a0 mm/swap.c:852 1 lock held by jbd2/sda1-8/4420: 1 lock held by syslogd/4438: 2 locks held by udevd/4456: 2 locks held by getty/4752: #0: ffff88814a633098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x26/0x80 drivers/tty/tty_ldisc.c:243 #1: ffffc900015902f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0xef4/0x13e0 drivers/tty/n_tty.c:2176 4 locks held by syz-fuzzer/5036: 2 locks held by syz-fuzzer/5038: 2 locks held by syz-fuzzer/5955: 1 lock held by syz-executor.5/5044: 3 locks held by syz-executor.4/5047: #0: ffff88807ba95028 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close+0x29/0x70 net/bluetooth/hci_core.c:552 #1: ffff88807ba94078 (&hdev->lock){+.+.}-{3:3}, at: hci_dev_close_sync+0x306/0x1200 net/bluetooth/hci_sync.c:4928 #2: ffffffff8c7a4538 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:293 [inline] #2: ffffffff8c7a4538 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x64a/0x770 kernel/rcu/tree_exp.h:992 1 lock held by syz-executor.3/5058: 3 locks held by kworker/u4:1/5074: 3 locks held by kworker/u4:2/5076: 3 locks held by kworker/u4:3/5082: 3 locks held by kworker/u4:6/5171: 3 locks held by kworker/u4:10/8394: 3 locks held by kworker/u4:13/8448: 6 locks held by kworker/u4:15/8461: #0: ffff888012479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff888012479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline] #0: ffff888012479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1324 [inline] #0: ffff888012479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:643 [inline] #0: ffff888012479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:670 [inline] #0: ffff888012479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x883/0x15e0 kernel/workqueue.c:2378 #1: ffffc9000342fdb0 ((work_completion)(&buf->work)){+.+.}-{0:0}, at: process_one_work+0x8b7/0x15e0 kernel/workqueue.c:2382 #2: ffff888012e420b8 (&buf->lock){+.+.}-{3:3}, at: flush_to_ldisc+0x44/0x700 drivers/tty/tty_buffer.c:537 #3: ffff88803e5a1098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref+0x21/0x90 drivers/tty/tty_ldisc.c:263 #4: ffff88803e5a12e8 (&tty->termios_rwsem){++++}-{3:3}, at: n_tty_receive_buf_common+0x7f/0x1540 drivers/tty/n_tty.c:1673 #5: ffffc9000bea1380 (&ldata->output_lock){+.+.}-{3:3}, at: commit_echoes+0x4c/0x210 drivers/tty/n_tty.c:765 6 locks held by kworker/u4:17/8552: 3 locks held by kworker/u4:18/9097: 4 locks held by syz-executor.2/9209: #0: ffff8880806ed028 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close+0x29/0x70 net/bluetooth/hci_core.c:552 #1: ffff8880806ec078 (&hdev->lock){+.+.}-{3:3}, at: hci_dev_close_sync+0x306/0x1200 net/bluetooth/hci_sync.c:4928 #2: ffffffff8e34be48 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1831 [inline] #2: ffffffff8e34be48 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xc4/0x230 net/bluetooth/hci_conn.c:2484 #3: ffffffff8c7a4538 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:325 [inline] #3: ffffffff8c7a4538 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3e8/0x770 kernel/rcu/tree_exp.h:992 3 locks held by kworker/u4:11/12523: 3 locks held by kworker/u4:19/13926: 3 locks held by kworker/u4:20/14261: 3 locks held by kworker/0:8/14940: 3 locks held by kworker/u4:12/16177: 2 locks held by kworker/0:12/16981: #0: ffff888012472538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff888012472538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline] #0: ffff888012472538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1324 [inline] #0: ffff888012472538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:643 [inline] #0: ffff888012472538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:670 [inline] #0: ffff888012472538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x883/0x15e0 kernel/workqueue.c:2378 #1: ffffc900063afdb0 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x8b7/0x15e0 kernel/workqueue.c:2382 3 locks held by kworker/1:6/20672: 2 locks held by kworker/0:13/21148: 3 locks held by syz-executor.1/23700: #0: ffff88803d921028 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close+0x29/0x70 net/bluetooth/hci_core.c:552 #1: ffff88803d920078 (&hdev->lock){+.+.}-{3:3}, at: hci_dev_close_sync+0x306/0x1200 net/bluetooth/hci_sync.c:4928 #2: ffffffff8e34be48 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1831 [inline] #2: ffffffff8e34be48 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xc4/0x230 net/bluetooth/hci_conn.c:2484 6 locks held by syz-executor.0/23945: 1 lock held by rm/23966: ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 28 Comm: khungtaskd Not tainted 6.4.0-rc2-next-20230515-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106 nmi_cpu_backtrace+0x29c/0x350 lib/nmi_backtrace.c:113 nmi_trigger_cpumask_backtrace+0x2a4/0x300 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline] watchdog+0xe16/0x1090 kernel/hung_task.c:379 kthread+0x344/0x440 kernel/kthread.c:379 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 8552 Comm: kworker/u4:17 Not tainted 6.4.0-rc2-next-20230515-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023 Workqueue: bat_events batadv_purge_orig RIP: 0010:write_comp_data+0xc/0x90 kernel/kcov.c:230 Code: 00 75 10 65 48 8b 04 25 c0 bb 03 00 48 8b 80 00 16 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 65 8b 05 41 9d 7f 7e 49 89 f1 89 c6 <49> 89 d2 81 e6 00 01 00 00 49 89 f8 65 48 8b 14 25 c0 bb 03 00 a9 RSP: 0018:ffffc900000071a8 EFLAGS: 00000202 RAX: 0000000080000101 RBX: 0000000000000001 RCX: ffffffff884d8a0e RDX: 0000000000000001 RSI: 0000000080000101 RDI: 0000000000000005 RBP: ffffffff8b646da0 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 1c0000ff01000000 R12: 0000000000000001 R13: 0000000000000005 R14: 0000000000000003 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000c01a9cd000 CR3: 0000000022435000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 000000000000003b DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: __sanitizer_cov_trace_switch+0x54/0x90 kernel/kcov.c:340 nf_hook_slow+0xde/0x1f0 net/netfilter/core.c:627 nf_hook+0x444/0x760 include/linux/netfilter.h:258 NF_HOOK include/linux/netfilter.h:301 [inline] br_nf_forward_ip net/bridge/br_netfilter_hooks.c:637 [inline] br_nf_forward_ip+0xb58/0x13c0 net/bridge/br_netfilter_hooks.c:578 nf_hook_entry_hookfn include/linux/netfilter.h:143 [inline] nf_hook_slow+0xc9/0x1f0 net/netfilter/core.c:626 nf_hook+0x431/0x730 include/linux/netfilter.h:258 NF_HOOK include/linux/netfilter.h:301 [inline] __br_forward+0x19a/0x570 net/bridge/br_forward.c:115 deliver_clone net/bridge/br_forward.c:131 [inline] br_flood+0x383/0x470 net/bridge/br_forward.c:242 br_handle_frame_finish+0xf89/0x1de0 net/bridge/br_input.c:210 br_nf_hook_thresh+0x2fb/0x3f0 net/bridge/br_netfilter_hooks.c:1048 br_nf_pre_routing_finish_ipv6+0x695/0xf30 net/bridge/br_netfilter_ipv6.c:148 NF_HOOK include/linux/netfilter.h:303 [inline] br_nf_pre_routing_ipv6+0x41b/0x830 net/bridge/br_netfilter_ipv6.c:178 br_nf_pre_routing+0xda4/0x1520 net/bridge/br_netfilter_hooks.c:508 nf_hook_entry_hookfn include/linux/netfilter.h:143 [inline] nf_hook_bridge_pre net/bridge/br_input.c:272 [inline] br_handle_frame+0x9cb/0x1320 net/bridge/br_input.c:416 __netif_receive_skb_core+0xa10/0x3900 net/core/dev.c:5385 __netif_receive_skb_one_core+0xae/0x180 net/core/dev.c:5489 __netif_receive_skb+0x1f/0x1c0 net/core/dev.c:5605 process_backlog+0x13e/0x6d0 net/core/dev.c:5933 __napi_poll+0xb3/0x520 net/core/dev.c:6496 napi_poll net/core/dev.c:6563 [inline] net_rx_action+0x8e4/0xd00 net/core/dev.c:6696 __do_softirq+0x1d4/0x905 kernel/softirq.c:553 do_softirq.part.0+0x87/0xc0 kernel/softirq.c:454 do_softirq kernel/softirq.c:446 [inline] __local_bh_enable_ip+0x106/0x130 kernel/softirq.c:381 spin_unlock_bh include/linux/spinlock.h:395 [inline] batadv_purge_orig_ref+0xeb8/0x1590 net/batman-adv/originator.c:1259 batadv_purge_orig+0x1b/0x60 net/batman-adv/originator.c:1272 process_one_work+0x99a/0x15e0 kernel/workqueue.c:2407 worker_thread+0x67d/0x10c0 kernel/workqueue.c:2554 kthread+0x344/0x440 kernel/kthread.c:379 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308