INFO: task kworker/u8:4:63 blocked for more than 143 seconds. Not tainted 6.14.0-next-20250402-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u8:4 state:D stack:21040 pid:63 tgid:63 ppid:2 task_flags:0x4208060 flags:0x00004000 Workqueue: events_unbound flush_to_ldisc Call Trace: context_switch kernel/sched/core.c:5382 [inline] __schedule+0x1b88/0x5240 kernel/sched/core.c:6767 __schedule_loop kernel/sched/core.c:6845 [inline] schedule+0x163/0x360 kernel/sched/core.c:6860 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6917 __mutex_lock_common kernel/locking/mutex.c:678 [inline] __mutex_lock+0x805/0x10c0 kernel/locking/mutex.c:746 commit_echoes drivers/tty/n_tty.c:740 [inline] n_tty_receive_char+0x5e5/0xb80 drivers/tty/n_tty.c:1421 n_tty_receive_buf_standard+0x65c/0x5420 drivers/tty/n_tty.c:1590 __receive_buf drivers/tty/n_tty.c:1624 [inline] n_tty_receive_buf_common+0xa88/0x12e0 drivers/tty/n_tty.c:1723 tty_port_default_receive_buf+0x6d/0xa0 drivers/tty/tty_port.c:37 receive_buf drivers/tty/tty_buffer.c:445 [inline] flush_to_ldisc+0x32b/0x860 drivers/tty/tty_buffer.c:495 process_one_work kernel/workqueue.c:3238 [inline] process_scheduled_works+0xac3/0x18e0 kernel/workqueue.c:3319 worker_thread+0x870/0xd50 kernel/workqueue.c:3400 kthread+0x7b7/0x940 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Showing all locks held in the system: 2 locks held by kthreadd/2: 1 lock held by kworker/R-kvfre/6: #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_detach_from_pool kernel/workqueue.c:2736 [inline] #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: rescuer_thread+0xa44/0x1020 kernel/workqueue.c:3529 3 locks held by kworker/0:1/10: #0: ffff88801b080d48 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline] #0: ffff88801b080d48 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x990/0x18e0 kernel/workqueue.c:3319 #1: ffffc900000f7c60 (free_ipc_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline] #1: ffffc900000f7c60 (free_ipc_work){+.+.}-{0:0}, at: process_scheduled_works+0x9cb/0x18e0 kernel/workqueue.c:3319 #2: ffffffff8ed43538 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:336 [inline] #2: ffffffff8ed43538 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x454/0x830 kernel/rcu/tree_exp.h:998 3 locks held by kworker/u8:0/12: 3 locks held by kworker/u8:1/13: 1 lock held by kworker/R-mm_pe/14: #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_detach_from_pool kernel/workqueue.c:2736 [inline] #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: rescuer_thread+0xa44/0x1020 kernel/workqueue.c:3529 2 locks held by kworker/1:0/24: 1 lock held by khungtaskd/31: #0: ffffffff8ed3e000 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #0: ffffffff8ed3e000 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #0: ffffffff8ed3e000 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x30/0x180 kernel/locking/lockdep.c:6764 1 lock held by kworker/R-write/33: #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_attach_to_pool+0x31/0x390 kernel/workqueue.c:2678 3 locks held by kworker/u8:2/36: 1 lock held by kworker/1:1/52: #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_attach_to_pool+0x31/0x390 kernel/workqueue.c:2678 3 locks held by kworker/u8:3/53: 6 locks held by kworker/u8:4/63: #0: ffff88801b089148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline] #0: ffff88801b089148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x990/0x18e0 kernel/workqueue.c:3319 #1: ffffc90001557c60 ((work_completion)(&buf->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline] #1: ffffc90001557c60 ((work_completion)(&buf->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9cb/0x18e0 kernel/workqueue.c:3319 #2: ffff88801b0a10b8 (&buf->lock){+.+.}-{4:4}, at: flush_to_ldisc+0x38/0x860 drivers/tty/tty_buffer.c:467 #3: ffff88805ec930a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref+0x1c/0x80 drivers/tty/tty_ldisc.c:263 #4: ffff88805ec932e8 (&tty->termios_rwsem){++++}-{4:4}, at: n_tty_receive_buf_common+0x87/0x12e0 drivers/tty/n_tty.c:1686 #5: ffffc900031f0380 (&ldata->output_lock){+.+.}-{4:4}, at: commit_echoes drivers/tty/n_tty.c:740 [inline] #5: ffffc900031f0380 (&ldata->output_lock){+.+.}-{4:4}, at: n_tty_receive_char+0x5e5/0xb80 drivers/tty/n_tty.c:1421 2 locks held by kworker/1:2/975: 6 locks held by kworker/u8:5/1084: 1 lock held by kworker/R-dm_bu/2813: #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_attach_to_pool+0x31/0x390 kernel/workqueue.c:2678 1 lock held by kworker/R-ipv6_/3170: #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_attach_to_pool+0x31/0x390 kernel/workqueue.c:2678 1 lock held by kworker/R-bat_e/3400: #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_detach_from_pool kernel/workqueue.c:2736 [inline] #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: rescuer_thread+0xa44/0x1020 kernel/workqueue.c:3529 3 locks held by kworker/u8:6/3454: 2 locks held by syslogd/5192: 2 locks held by udevd/5210: 1 lock held by dhcpcd/5503: 1 lock held by dhcpcd/5504: 2 locks held by getty/5588: #0: ffff88814df800a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffc9000332e2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x5bb/0x1700 drivers/tty/n_tty.c:2222 1 lock held by syz-executor/5822: 3 locks held by syz-executor/5832: 1 lock held by syz-executor/5834: 2 locks held by syz-executor/5847: 3 locks held by syz-executor/5849: 1 lock held by kworker/R-wg-cr/5868: #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_detach_from_pool kernel/workqueue.c:2736 [inline] #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: rescuer_thread+0xa44/0x1020 kernel/workqueue.c:3529 1 lock held by kworker/R-wg-cr/5869: #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_detach_from_pool kernel/workqueue.c:2736 [inline] #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: rescuer_thread+0xa44/0x1020 kernel/workqueue.c:3529 1 lock held by kworker/R-wg-cr/5870: #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_detach_from_pool kernel/workqueue.c:2736 [inline] #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: rescuer_thread+0xa44/0x1020 kernel/workqueue.c:3529 1 lock held by kworker/R-wg-cr/5871: #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_detach_from_pool kernel/workqueue.c:2736 [inline] #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: rescuer_thread+0xa44/0x1020 kernel/workqueue.c:3529 1 lock held by kworker/R-wg-cr/5872: #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_detach_from_pool kernel/workqueue.c:2736 [inline] #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: rescuer_thread+0xa44/0x1020 kernel/workqueue.c:3529 1 lock held by kworker/R-wg-cr/5873: #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_detach_from_pool kernel/workqueue.c:2736 [inline] #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: rescuer_thread+0xa44/0x1020 kernel/workqueue.c:3529 1 lock held by kworker/R-wg-cr/5874: 1 lock held by kworker/R-wg-cr/5875: #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_detach_from_pool kernel/workqueue.c:2736 [inline] #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: rescuer_thread+0xa44/0x1020 kernel/workqueue.c:3529 1 lock held by kworker/R-wg-cr/5876: #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_detach_from_pool kernel/workqueue.c:2736 [inline] #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: rescuer_thread+0xa44/0x1020 kernel/workqueue.c:3529 1 lock held by kworker/R-wg-cr/5877: #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_attach_to_pool+0x31/0x390 kernel/workqueue.c:2678 1 lock held by kworker/R-wg-cr/5878: #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_detach_from_pool kernel/workqueue.c:2736 [inline] #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: rescuer_thread+0xa44/0x1020 kernel/workqueue.c:3529 1 lock held by kworker/R-wg-cr/5879: #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_detach_from_pool kernel/workqueue.c:2736 [inline] #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: rescuer_thread+0xa44/0x1020 kernel/workqueue.c:3529 1 lock held by kworker/R-wg-cr/5880: #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_detach_from_pool kernel/workqueue.c:2736 [inline] #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: rescuer_thread+0xa44/0x1020 kernel/workqueue.c:3529 1 lock held by kworker/R-wg-cr/5881: #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_detach_from_pool kernel/workqueue.c:2736 [inline] #0: ffffffff8ebe5468 (wq_pool_attach_mutex){+.+.}-{4:4}, at: rescuer_thread+0xa44/0x1020 kernel/workqueue.c:3529 2 locks held by kworker/1:3/5886: 3 locks held by kworker/1:4/5887: 3 locks held by kworker/1:5/5888: 5 locks held by kworker/0:6/5900: 3 locks held by kworker/u8:7/5904: 3 locks held by kworker/u8:8/5910: 2 locks held by kworker/1:6/5934: 1 lock held by udevd/5997: 6 locks held by syz.2.837/8210: 3 locks held by kworker/u8:9/8232: 3 locks held by kworker/u8:10/8233: 4 locks held by kworker/u8:11/8234: 4 locks held by kworker/u8:12/8235: ============================================= NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.14.0-next-20250402-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 nmi_cpu_backtrace+0x4ab/0x4e0 lib/nmi_backtrace.c:113 nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:274 [inline] watchdog+0x1058/0x10a0 kernel/hung_task.c:437 kthread+0x7b7/0x940 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 1084 Comm: kworker/u8:5 Not tainted 6.14.0-next-20250402-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Workqueue: events_unbound cfg80211_wiphy_work RIP: 0010:__local_bh_enable_ip+0x139/0x200 kernel/softirq.c:402 Code: ff 00 00 3d 00 02 00 00 75 0a 48 8b 7c 24 18 e8 9d 9c 1a 00 b8 01 00 00 00 44 29 f8 65 01 05 2e 8e e4 11 65 8b 05 27 8e e4 11 00 ff ff 00 75 19 48 c7 c7 60 91 49 8c e8 a4 40 ac 0a 65 66 8b RSP: 0018:ffffc90000006900 EFLAGS: 00000083 RAX: 0000000080000102 RBX: 1ffff92000000d28 RCX: ffffffff81cb471c RDX: 0000000000000000 RSI: ffffffff8ca1db20 RDI: ffffffff8ca1dae0 RBP: ffffc900000069b0 R08: ffffffff905ff137 R09: 1ffffffff20bfe26 R10: dffffc0000000000 R11: fffffbfff20bfe27 R12: 1ffff92000000d24 R13: dffffc0000000000 R14: ffffc90000006940 R15: 0000000000000200 FS: 0000000000000000(0000) GS:ffff888124f93000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f62ecd77678 CR3: 0000000034cc4000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: local_bh_enable include/linux/bottom_half.h:33 [inline] ip6t_do_table+0x1695/0x18c0 net/ipv6/netfilter/ip6_tables.c:375 nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline] nf_hook_slow+0xc8/0x220 net/netfilter/core.c:626 nf_hook include/linux/netfilter.h:269 [inline] NF_HOOK+0x5ea/0x780 include/linux/netfilter.h:312 br_nf_forward_ip+0x61e/0x7b0 net/bridge/br_netfilter_hooks.c:719 nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline] nf_hook_slow+0xc8/0x220 net/netfilter/core.c:626 nf_hook include/linux/netfilter.h:269 [inline] NF_HOOK+0x2ac/0x460 include/linux/netfilter.h:312 __br_forward+0x46a/0x640 net/bridge/br_forward.c:115 deliver_clone net/bridge/br_forward.c:131 [inline] maybe_deliver+0xb3/0x150 net/bridge/br_forward.c:190 br_flood+0x2e4/0x680 net/bridge/br_forward.c:237 br_handle_frame_finish+0x185b/0x1f60 net/bridge/br_input.c:220 br_nf_hook_thresh+0x482/0x5a0 net/bridge/br_netfilter_hooks.c:1170 br_nf_pre_routing_finish_ipv6+0xaa3/0xdd0 net/bridge/br_netfilter_ipv6.c:-1 NF_HOOK include/linux/netfilter.h:314 [inline] br_nf_pre_routing_ipv6+0x397/0x790 net/bridge/br_netfilter_ipv6.c:184 nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline] nf_hook_bridge_pre net/bridge/br_input.c:282 [inline] br_handle_frame+0x9fa/0x1530 net/bridge/br_input.c:433 __netif_receive_skb_core+0x155a/0x4bb0 net/core/dev.c:5777 __netif_receive_skb_one_core net/core/dev.c:5889 [inline] __netif_receive_skb+0x130/0x670 net/core/dev.c:6004 process_backlog+0x664/0x15c0 net/core/dev.c:6356 __napi_poll+0xcb/0x480 net/core/dev.c:7328 napi_poll net/core/dev.c:7392 [inline] net_rx_action+0x89d/0x1240 net/core/dev.c:7514 handle_softirqs+0x2d6/0x9b0 kernel/softirq.c:579 do_softirq+0x11f/0x1e0 kernel/softirq.c:480 __local_bh_enable_ip+0x1be/0x200 kernel/softirq.c:407 spin_unlock_bh include/linux/spinlock.h:396 [inline] cfg80211_inform_single_bss_data+0x1629/0x1ed0 net/wireless/scan.c:2383 cfg80211_inform_bss_data+0x3c5/0x5860 net/wireless/scan.c:3222 cfg80211_inform_bss_frame_data+0x3c5/0x720 net/wireless/scan.c:3317 ieee80211_bss_info_update+0x8ac/0xbc0 net/mac80211/scan.c:226 ieee80211_rx_bss_info net/mac80211/ibss.c:1102 [inline] ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1581 [inline] ieee80211_ibss_rx_queued_mgmt+0x19ce/0x2e20 net/mac80211/ibss.c:1608 ieee80211_iface_process_skb net/mac80211/iface.c:1622 [inline] ieee80211_iface_work+0x933/0x1100 net/mac80211/iface.c:1676 cfg80211_wiphy_work+0x2f0/0x490 net/wireless/core.c:435 process_one_work kernel/workqueue.c:3238 [inline] process_scheduled_works+0xac3/0x18e0 kernel/workqueue.c:3319 worker_thread+0x870/0xd50 kernel/workqueue.c:3400 kthread+0x7b7/0x940 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245