INFO: task udevd:2858 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:udevd state:D stack:25752 pid:2858 tgid:2858 ppid:1 task_flags:0x400140 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x1325/0x47d0 kernel/sched/core.c:7234 __schedule_loop kernel/sched/core.c:7311 [inline] schedule+0xdd/0x2c0 kernel/sched/core.c:7326 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7383 rwsem_down_read_slowpath+0x5af/0xb40 kernel/locking/rwsem.c:1114 __down_read_common kernel/locking/rwsem.c:1291 [inline] __down_read kernel/locking/rwsem.c:1304 [inline] down_read+0xed/0x4c0 kernel/locking/rwsem.c:1576 kernfs_dop_revalidate+0xa5/0x7e0 fs/kernfs/dir.c:1217 d_revalidate fs/namei.c:1035 [inline] d_revalidate fs/namei.c:1031 [inline] lookup_fast+0x3c7/0x600 fs/namei.c:1881 walk_component fs/namei.c:2278 [inline] link_path_walk+0x7d4/0x1cc0 fs/namei.c:2656 path_openat+0x1c9/0x4280 fs/namei.c:4855 do_file_open+0x20e/0x430 fs/namei.c:4888 do_sys_openat2+0x10f/0x1e0 fs/open.c:1368 do_sys_open fs/open.c:1374 [inline] __do_sys_openat fs/open.c:1390 [inline] __se_sys_openat fs/open.c:1385 [inline] __x64_sys_openat+0x12d/0x210 fs/open.c:1385 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/0x7f0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f2e28c00c3a RSP: 002b:00007fff406de868 EFLAGS: 00000206 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000557ae4647ba0 RCX: 00007f2e28c00c3a RDX: 0000000000090800 RSI: 0000557ae4636530 RDI: 00000000ffffff9c RBP: 0000557ae4636530 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000000 R11: 0000000000000206 R12: 0000557ae461e9c0 R13: 00000000000000fd R14: 0000557ad821bbe0 R15: 00007fff406deb70 Showing all locks held in the system: 4 locks held by kworker/0:1/11: #0: ffff88810006b140 ( (wq_completion)events ){+.+.}-{0:0} , at: process_one_work+0x12b1/0x1940 kernel/workqueue.c:3297 #1: ffffc900000bfd18 ( kernfs_notify_work){+.+.}-{0:0}, at: process_one_work+0x988/0x1940 kernel/workqueue.c:3298 #2: ffff888100e87aa0 ( &root->kernfs_supers_rwsem){++++}-{4:4} , at: kernfs_notify_workfn+0xf7/0x5f0 fs/kernfs/file.c:925 #3: ffff888100e87980 ( &root->kernfs_rwsem){++++}-{4:4}, at: kernfs_notify_workfn+0xff/0x5f0 fs/kernfs/file.c:926 5 locks held by kworker/1:1/28: 1 lock held by khungtaskd/30: #0: ffffffff896e3000 ( rcu_read_lock ){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] ){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline] ){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775 3 locks held by kworker/u8:8/346: #0: ffff888100e98940 ( (wq_completion)netns ){+.+.}-{0:0} , at: process_one_work+0x12b1/0x1940 kernel/workqueue.c:3297 #1: ffffc9000199fd18 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x988/0x1940 kernel/workqueue.c:3298 #2: ffffffff8ab090e8 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xb8/0x920 net/core/net_namespace.c:673 7 locks held by kworker/1:2/705: 1 lock held by udevd/2858: #0: ffff888100e87980 ( &root->kernfs_rwsem ){++++}-{4:4} , at: kernfs_dop_revalidate+0xa5/0x7e0 fs/kernfs/dir.c:1217 2 locks held by getty/2920: #0: ffff8881127eb0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243 #1: ffffc900000452e8 (&ldata->atomic_read_lock){+.+.}-{4:4} , at: n_tty_read+0x419/0x14e0 drivers/tty/n_tty.c:2211 1 lock held by syz-executor/2974: #0: ffffffff896eeaa8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x19e/0x3c0 kernel/rcu/tree_exp.h:343 5 locks held by syz-executor/2977: 3 locks held by kworker/0:4/5224: #0: ffff88810006b140 ( (wq_completion)events ){+.+.}-{0:0} , at: process_one_work+0x12b1/0x1940 kernel/workqueue.c:3297 #1: ffffc9000256fd18 (free_ipc_work){+.+.}-{0:0}, at: process_one_work+0x988/0x1940 kernel/workqueue.c:3298 #2: ffffffff896eeaa8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x19e/0x3c0 kernel/rcu/tree_exp.h:343 4 locks held by udevd/5226: #0: ffff88811a45dbd8 ( &p->lock ){+.+.}-{4:4} , at: seq_read_iter+0xe1/0x1270 fs/seq_file.c:183 #1: ffff888119b86880 (&of->mutex #2){+.+.}-{4:4}, at: kernfs_seq_start+0x4f/0x2a0 fs/kernfs/file.c:165 #2: ffff88811c8bfe18 (kn->active#23){.+.+}-{0:0} , at: kernfs_get_active_of fs/kernfs/file.c:73 [inline] , at: kernfs_seq_start+0xbc/0x2a0 fs/kernfs/file.c:166 #3: ffff88811a8591d8 ( &dev->mutex ){....}-{4:4} , at: device_lock_interruptible include/linux/device.h:1107 [inline] , at: manufacturer_show+0x26/0xa0 drivers/usb/core/sysfs.c:142 6 locks held by kworker/1:3/5235: 4 locks held by kworker/1:4/5265: 2 locks held by syz-executor/5285: 2 locks held by syz-executor/5286: 2 locks held by syz-executor/5287: 2 locks held by modprobe/5294: ============================================= NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 30 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(lazy) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 nmi_cpu_backtrace.cold+0x12d/0x151 lib/nmi_backtrace.c:122 nmi_trigger_cpumask_backtrace+0x21c/0x2a0 lib/nmi_backtrace.c:65 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline] __sys_info lib/sys_info.c:157 [inline] sys_info+0x141/0x190 lib/sys_info.c:165 check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline] watchdog+0xcb1/0x1030 kernel/hung_task.c:561 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x69a/0xc80 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Sending NMI from CPU 0 to CPUs 1: yealink 3-1:36.0: urb_ctl_callback - urb status -71 NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 5285 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(lazy) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 RIP: 0010:io_serial_in+0x87/0xb0 drivers/tty/serial/8250/8250_port.c:402 Code: ae 88 fe 48 8d 7d 40 44 89 e1 48 b8 00 00 00 00 00 fc ff df 48 89 fa d3 e3 48 c1 ea 03 80 3c 02 00 75 1a 66 03 5d 40 89 da ec <5b> 0f b6 c0 5d 41 5c e9 7d 7b 52 04 e8 68 08 f1 fe eb a2 e8 f1 08 RSP: 0000:ffffc900001a8460 EFLAGS: 00000002 RAX: dffffc0000000000 RBX: 00000000000003fd RCX: 0000000000000000 RDX: 00000000000003fd RSI: ffffffff832b5bb0 RDI: ffffffff9423fd60 RBP: ffffffff9423fd20 R08: 0000000000000001 R09: 000000000000001f R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000020 R14: fffffbfff2847ffe R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff888268740000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00005555761750b8 CR3: 0000000116848000 CR4: 00000000003506f0 Call Trace: serial_in drivers/tty/serial/8250/8250.h:128 [inline] serial_lsr_in drivers/tty/serial/8250/8250.h:150 [inline] wait_for_lsr+0x13a/0x210 drivers/tty/serial/8250/8250_port.c:1982 serial8250_fifo_wait_for_lsr_thre drivers/tty/serial/8250/8250_port.c:3229 [inline] serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3294 [inline] serial8250_console_write+0xdfd/0x1a50 drivers/tty/serial/8250/8250_port.c:3379 console_emit_next_record kernel/printk/printk.c:3183 [inline] console_flush_one_record+0x790/0xe50 kernel/printk/printk.c:3269 console_flush_all kernel/printk/printk.c:3343 [inline] __console_flush_and_unlock kernel/printk/printk.c:3373 [inline] console_unlock+0x103/0x260 kernel/printk/printk.c:3413 vprintk_emit+0x407/0x6b0 kernel/printk/printk.c:2479 dev_vprintk_emit+0x391/0x3e0 drivers/base/core.c:4996 dev_printk_emit+0xd2/0x10d drivers/base/core.c:5007 __dev_printk+0xcb/0x100 drivers/base/core.c:5019 _dev_err+0xef/0x127 drivers/base/core.c:5062 urb_ctl_callback.cold+0x41/0x8c drivers/input/misc/yealink.c:447 __usb_hcd_giveback_urb+0x38d/0x610 drivers/usb/core/hcd.c:1657 usb_hcd_giveback_urb+0x3ca/0x4a0 drivers/usb/core/hcd.c:1741 dummy_timer+0xda1/0x36c0 drivers/usb/gadget/udc/dummy_hcd.c:2005 __run_hrtimer kernel/time/hrtimer.c:2032 [inline] __hrtimer_run_queues+0x462/0x9c0 kernel/time/hrtimer.c:2096 hrtimer_run_softirq+0x17d/0x2c0 kernel/time/hrtimer.c:2113 handle_softirqs+0x1dd/0x990 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] invoke_softirq kernel/softirq.c:496 [inline] __irq_exit_rcu+0x160/0x210 kernel/softirq.c:735 irq_exit_rcu+0x9/0x30 kernel/softirq.c:752 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0x8f/0xb0 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:write_comp_data+0x7/0x90 kernel/kcov.c:240 Code: 7c 24 08 e8 8b 62 68 00 e9 6d fd ff ff 66 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 65 8b 05 b9 fd 49 0b <49> 89 f8 49 89 f1 49 89 d2 65 48 8b 3d 90 fd 49 0b a9 00 01 ff 00 RSP: 0000:ffffc900014bf570 EFLAGS: 00000246 RAX: 0000000080000001 RBX: 00000000ffffffff RCX: ffffffff8206526b RDX: 00000000ffffffff RSI: 00000000ff000000 RDI: 0000000000000005 RBP: ffffc900014bf738 R08: 0000000000000000 R09: fffff940009dc2c6 R10: ffffea0004ee1633 R11: 0000000000000000 R12: ffffea0004ee1600 R13: 00007f2713ce7000 R14: 0000000000000000 R15: 800000013b858027 folio_mapcount include/linux/mm.h:1917 [inline] zap_present_folio_ptes mm/memory.c:1674 [inline] zap_present_ptes mm/memory.c:1730 [inline] do_zap_pte_range mm/memory.c:1832 [inline] zap_pte_range mm/memory.c:1934 [inline] zap_pmd_range mm/memory.c:2020 [inline] zap_pud_range mm/memory.c:2048 [inline] zap_p4d_range mm/memory.c:2069 [inline] __zap_vma_range+0x1b3b/0x3fd0 mm/memory.c:2109 unmap_vmas+0x299/0x5f0 mm/memory.c:2178 exit_mmap+0x1ef/0xa00 mm/mmap.c:1300 __mmput kernel/fork.c:1182 [inline] mmput+0xe0/0x430 kernel/fork.c:1205 exit_mm kernel/exit.c:610 [inline] do_exit+0x833/0x2a50 kernel/exit.c:992 do_group_exit+0xd5/0x2a0 kernel/exit.c:1147 get_signal+0x1ec7/0x21e0 kernel/signal.c:3038 arch_do_signal_or_restart+0x91/0x7e0 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline] exit_to_user_mode_loop+0xd2/0x530 kernel/entry/common.c:101 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline] do_syscall_64+0x682/0x7f0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f27141e7fd7 Code: Unable to access opcode bytes at 0x7f27141e7fad. RSP: 002b:00007ffdc520a2b0 EFLAGS: 00000202 ORIG_RAX: 0000000000000101 RAX: 0000000000000003 RBX: 000055558f470500 RCX: 00007f27141e7fd7 RDX: 0000000000000002 RSI: 00007f27142c2537 RDI: ffffffffffffff9c RBP: 00007f27144a6218 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 0000000000000003 R14: 00007ffdc520a5a8 R15: 0000000000000000