INFO: task syz.0.18:6012 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.0.18 state:D stack:26880 pid:6012 tgid:6010 ppid:5931 task_flags:0x400140 flags:0x00080003 Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x1480/0x50a0 kernel/sched/core.c:6863 __schedule_loop kernel/sched/core.c:6945 [inline] rt_mutex_schedule+0x77/0xf0 kernel/sched/core.c:7241 rt_mutex_slowlock_block+0x5ba/0x6d0 kernel/locking/rtmutex.c:1647 __rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline] __rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1760 [inline] rt_mutex_slowlock+0x2a8/0x6b0 kernel/locking/rtmutex.c:1800 __rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline] __mutex_lock_common kernel/locking/rtmutex_api.c:534 [inline] mutex_lock_nested+0x16a/0x1d0 kernel/locking/rtmutex_api.c:552 bdev_release+0x1af/0x660 block/bdev.c:1145 blkdev_release+0x15/0x20 block/fops.c:706 __fput+0x45b/0xa80 fs/file_table.c:468 task_work_run+0x1d4/0x260 kernel/task_work.c:233 get_signal+0x11c4/0x1310 kernel/signal.c:2807 arch_do_signal_or_restart+0x9a/0x7a0 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline] exit_to_user_mode_loop+0x87/0x4f0 kernel/entry/common.c:75 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline] do_syscall_64+0x2d0/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f091530f749 RSP: 002b:00007f0914955038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: 0000000000000000 RBX: 00007f0915566090 RCX: 00007f091530f749 RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003 RBP: 00007f0915393f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f0915566128 R14: 00007f0915566090 R15: 00007ffdf0493668 Showing all locks held in the system: 1 lock held by khungtaskd/38: #0: ffffffff8d5ae880 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #0: ffffffff8d5ae880 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #0: ffffffff8d5ae880 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775 2 locks held by getty/5558: #0: ffff8880350ed0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffc90003e8b2e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x44f/0x1460 drivers/tty/n_tty.c:2211 3 locks held by kworker/u9:2/5922: #0: ffff88805769a938 ((wq_completion)hci2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline] #0: ffff88805769a938 ((wq_completion)hci2){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x1770 kernel/workqueue.c:3340 #1: ffffc9000446fb80 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline] #1: ffffc9000446fb80 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x1770 kernel/workqueue.c:3340 #2: ffff888040608f80 (&hdev->req_lock){+.+.}-{4:4}, at: hci_cmd_sync_work+0x1d3/0x400 net/bluetooth/hci_sync.c:331 1 lock held by udevd/5956: #0: ffff888024bbc4c8 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xcc0 block/bdev.c:962 1 lock held by udevd/5957: #0: ffff888024c5f4c8 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xcc0 block/bdev.c:962 1 lock held by syz.0.18/6012: #0: ffff888024bbc4c8 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_release+0x1af/0x660 block/bdev.c:1145 2 locks held by kworker/1:4/6038: 1 lock held by syz.1.22/6049: #0: ffff888024c5f4c8 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_release+0x1af/0x660 block/bdev.c:1145 1 lock held by udevd/6053: #0: ffff888024ca44c8 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xcc0 block/bdev.c:962 1 lock held by syz.2.25/6077: #0: ffff888024ca44c8 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_release+0x1af/0x660 block/bdev.c:1145 1 lock held by udevd/6105: #0: ffff888024da44c8 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xcc0 block/bdev.c:962 1 lock held by syz.3.30/6110: #0: ffff888024da44c8 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_release+0x1af/0x660 block/bdev.c:1145 1 lock held by udevd/6143: #0: ffff888024e174c8 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xcc0 block/bdev.c:962 1 lock held by syz.4.34/6151: #0: ffff888024e174c8 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_release+0x1af/0x660 block/bdev.c:1145 1 lock held by udevd/6182: #0: ffff888024db44c8 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xcc0 block/bdev.c:962 1 lock held by syz.5.38/6188: #0: ffff888024db44c8 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_release+0x1af/0x660 block/bdev.c:1145 1 lock held by udevd/6193: #0: ffff888024e2f4c8 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xcc0 block/bdev.c:962 1 lock held by syz.6.53/6252: #0: ffff888024e2f4c8 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_release+0x1af/0x660 block/bdev.c:1145 1 lock held by udevd/6259: #0: ffff888024ecc4c8 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xcc0 block/bdev.c:962 1 lock held by syz.7.60/6302: #0: ffff888024ecc4c8 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_release+0x1af/0x660 block/bdev.c:1145 4 locks held by kworker/u8:19/6303: ============================================= NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 38 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline] __sys_info lib/sys_info.c:157 [inline] sys_info+0x135/0x170 lib/sys_info.c:165 check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline] watchdog+0xf95/0xfe0 kernel/hung_task.c:515 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 6303 Comm: kworker/u8:19 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Workqueue: bat_events batadv_dat_purge RIP: 0010:rt_mutex_set_owner kernel/locking/rtmutex.c:-1 [inline] RIP: 0010:try_to_take_rt_mutex+0x876/0xb00 kernel/locking/rtmutex.c:1191 Code: b9 00 00 00 00 00 fc ff df 80 3c 08 00 74 08 4c 89 f7 e8 ad 78 4c f7 4c 89 f8 48 83 c8 01 49 83 3e 00 49 0f 44 c7 49 87 45 00 01 00 00 00 89 e8 48 83 c4 48 5b 41 5c 41 5d 41 5e 41 5f 5d c3 RSP: 0018:ffffc900051c7620 EFLAGS: 00000046 RAX: 0000000000000001 RBX: ffff8880496de440 RCX: dffffc0000000000 RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffff8880496de450 RBP: 0000000000000000 R08: ffff8880496de457 R09: 1ffff110092dbc8a R10: dffffc0000000000 R11: ffffed10092dbc8b R12: 0000000000000000 R13: ffff8880496de450 R14: ffff8880496de440 R15: ffff888030acdac0 FS: 0000000000000000(0000) GS:ffff888126e03000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000020000000ae00 CR3: 000000000d3a8000 CR4: 00000000003526f0 Call Trace: rtlock_slowlock_locked+0xd8/0x4010 kernel/locking/rtmutex.c:1839 rtlock_slowlock kernel/locking/rtmutex.c:1895 [inline] rtlock_lock kernel/locking/spinlock_rt.c:43 [inline] __rt_spin_lock kernel/locking/spinlock_rt.c:49 [inline] rt_spin_lock+0x158/0x3e0 kernel/locking/spinlock_rt.c:57 spin_lock_bh include/linux/spinlock_rt.h:88 [inline] __batadv_dat_purge+0x131/0x400 net/batman-adv/distributed-arp-table.c:173 batadv_dat_purge+0x20/0x70 net/batman-adv/distributed-arp-table.c:204 process_one_work kernel/workqueue.c:3257 [inline] process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246