INFO: task syz-executor:5773 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor state:D stack:21704 pid:5773 ppid:1 flags:0x00004002 Call Trace: context_switch kernel/sched/core.c:5381 [inline] __schedule+0x1553/0x45a0 kernel/sched/core.c:6700 schedule+0xbd/0x170 kernel/sched/core.c:6774 wb_wait_for_completion+0x173/0x2a0 fs/fs-writeback.c:192 sync_inodes_sb+0x1c9/0xa10 fs/fs-writeback.c:2772 sync_filesystem+0x171/0x220 fs/sync.c:64 generic_shutdown_super+0x6f/0x2b0 fs/super.c:666 kill_block_super+0x44/0x90 fs/super.c:1660 deactivate_locked_super+0x97/0x100 fs/super.c:481 cleanup_mnt+0x43b/0x4d0 fs/namespace.c:1259 task_work_run+0x1d4/0x260 kernel/task_work.c:245 exit_task_work include/linux/task_work.h:43 [inline] do_exit+0x95a/0x2460 kernel/exit.c:883 do_group_exit+0x21b/0x2d0 kernel/exit.c:1024 __do_sys_exit_group kernel/exit.c:1035 [inline] __se_sys_exit_group kernel/exit.c:1033 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1033 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fde9fd9acb9 RSP: 002b:00007ffe653f4868 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 00007fde9fe047ae RCX: 00007fde9fd9acb9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001 RBP: 000000000000000c R08: 0000000000000000 R09: 00007fde9fe0471f R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe653f5b20 R13: 00007fde9fe0471f R14: 0000555555edb4e8 R15: 00007ffe653f6bf0 Showing all locks held in the system: 4 locks held by kworker/u4:0/11: 3 locks held by kworker/1:0/23: #0: ffff888017c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline] #0: ffff888017c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2711 #1: ffffc900001d7d00 (deferred_process_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline] #1: ffffc900001d7d00 (deferred_process_work){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2711 #2: ffffffff8e3bfe08 (rtnl_mutex){+.+.}-{3:3}, at: switchdev_deferred_process_work+0xe/0x20 net/switchdev/switchdev.c:104 1 lock held by khungtaskd/29: #0: ffffffff8d131fe0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline] #0: ffffffff8d131fe0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline] #0: ffffffff8d131fe0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633 3 locks held by kworker/u4:2/42: #0: ffff88814a85c538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline] #0: ffff88814a85c538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2711 #1: ffffc90000b2fd00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline] #1: ffffc90000b2fd00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2711 #2: ffffffff8e3bfe08 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xd4/0x1530 net/ipv6/addrconf.c:4176 3 locks held by kworker/u4:6/1032: #0: ffff888017c71538 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline] #0: ffff888017c71538 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2711 #1: ffffc9000448fd00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline] #1: ffffc9000448fd00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2711 #2: ffffffff8e3bfe08 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:286 2 locks held by kworker/u4:10/2940: #0: ffff8880186f4138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline] #0: ffff8880186f4138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2711 #1: ffffc9000be97d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline] #1: ffffc9000be97d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2711 1 lock held by dhcpcd/5434: #0: ffffffff8e3bfe08 (rtnl_mutex){+.+.}-{3:3}, at: devinet_ioctl+0x30c/0x1c40 net/ipv4/devinet.c:1101 2 locks held by getty/5532: #0: ffff88814dca00a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffc9000328b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x433/0x1390 drivers/tty/n_tty.c:2217 2 locks held by syz-executor/5773: #0: ffff8880766860e0 (&type->s_umount_key#57){+.+.}-{3:3}, at: __super_lock fs/super.c:56 [inline] #0: ffff8880766860e0 (&type->s_umount_key#57){+.+.}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline] #0: ffff8880766860e0 (&type->s_umount_key#57){+.+.}-{3:3}, at: deactivate_super+0xa4/0xe0 fs/super.c:513 #1: ffff8880219b27d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:364 [inline] #1: ffff8880219b27d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1ad/0xa10 fs/fs-writeback.c:2770 2 locks held by kworker/1:4/5821: #0: ffff888017c72538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline] #0: ffff888017c72538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2711 #1: ffffc900048ffd00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline] #1: ffffc900048ffd00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2711 6 locks held by kworker/1:7/5906: #0: ffff88801b6dc938 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline] #0: ffff88801b6dc938 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2711 #1: ffffc90004befd00 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline] #1: ffffc90004befd00 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2711 #2: ffff888142fb3190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:995 [inline] #2: ffff888142fb3190 (&dev->mutex){....}-{3:3}, at: hub_event+0x180/0x49f0 drivers/usb/core/hub.c:5861 #3: ffff888142fb6508 (&port_dev->status_lock){+.+.}-{3:3}, at: usb_lock_port drivers/usb/core/hub.c:3215 [inline] #3: ffff888142fb6508 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5426 [inline] #3: ffff888142fb6508 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5669 [inline] #3: ffff888142fb6508 (&port_dev->status_lock){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5833 [inline] #3: ffff888142fb6508 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_event+0x21d0/0x49f0 drivers/usb/core/hub.c:5915 #4: ffff888142797168 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5427 [inline] #4: ffff888142797168 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5669 [inline] #4: ffff888142797168 (hcd->address0_mutex){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5833 [inline] #4: ffff888142797168 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_event+0x21f8/0x49f0 drivers/usb/core/hub.c:5915 #5: ffffffff8dcc7430 (ehci_cf_port_reset_rwsem){.+.+}-{3:3}, at: hub_port_reset+0x164/0x1730 drivers/usb/core/hub.c:3030 1 lock held by syz-executor/7690: 1 lock held by syz-executor/8200: #0: ffffffff8e3bfe08 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline] #0: ffffffff8e3bfe08 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x811/0xfa0 net/core/rtnetlink.c:6469 1 lock held by syz-executor/8504: #0: ffffffff8e3bfe08 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline] #0: ffffffff8e3bfe08 (rtnl_mutex){+.+.}-{3:3}, at: __rtnl_newlink net/core/rtnetlink.c:3727 [inline] #0: ffffffff8e3bfe08 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_newlink+0xae9/0x20a0 net/core/rtnetlink.c:3750 1 lock held by syz.5.543/8566: #0: ffffffff8e3bfe08 (rtnl_mutex){+.+.}-{3:3}, at: __tun_chr_ioctl+0x400/0x2000 drivers/net/tun.c:3121 1 lock held by syz.5.543/8569: #0: ffffffff8e3bfe08 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline] #0: ffffffff8e3bfe08 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x811/0xfa0 net/core/rtnetlink.c:6469 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 29 Comm: khungtaskd Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106 nmi_cpu_backtrace+0x3a6/0x3e0 lib/nmi_backtrace.c:113 nmi_trigger_cpumask_backtrace+0x17a/0x2f0 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline] watchdog+0xf3d/0xf80 kernel/hung_task.c:379 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 60 Comm: kworker/u4:4 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Workqueue: bat_events batadv_nc_worker RIP: 0010:preempt_count_sub+0x51/0x160 kernel/sched/core.c:5878 Code: 83 3d 82 d4 cf 15 00 75 25 65 8b 05 c1 35 a7 7e 89 c1 81 e1 ff ff ff 7f 39 cf 7f 25 81 ff ff 00 00 00 0f 93 c1 84 c0 0f 95 c0 <08> c8 74 53 65 8b 05 9c 35 a7 7e f7 df 65 01 3d 93 35 a7 7e 5b 5d RSP: 0018:ffffc900015b7a08 EFLAGS: 00000002 RAX: 0000000080000001 RBX: dffffc0000000000 RCX: 0000000000000000 RDX: dffffc0000000000 RSI: ffffffff8ac9c180 RDI: 0000000000000001 RBP: ffffc900015b7ab8 R08: ffffffff8e8ad9ef R09: 1ffffffff1d15b3d R10: dffffc0000000000 R11: fffffbfff1d15b3e R12: ffffffff8a4c0131 R13: dffffc0000000000 R14: dffffc0000000000 R15: 1ffff920002b6f44 FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fa63f7e1198 CR3: 0000000019ab5000 CR4: 00000000003506e0 DR0: ffffffffffffffff DR1: 00000000000001f8 DR2: 0000000000000083 DR3: ffffffffefffff15 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: __local_bh_enable_ip+0x135/0x1c0 kernel/softirq.c:409 spin_unlock_bh include/linux/spinlock.h:396 [inline] batadv_nc_purge_paths+0x311/0x3a0 net/batman-adv/network-coding.c:471 batadv_nc_worker+0x328/0x610 net/batman-adv/network-coding.c:720 process_one_work kernel/workqueue.c:2634 [inline] process_scheduled_works+0xa5d/0x15d0 kernel/workqueue.c:2711 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293