INFO: task hung in uevent_show

Status: premoderation: reported syz repro on 2025/06/19 15:22
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+c93e88b253075f6a44b4@syzkaller.appspotmail.com
First crash: 411d, last: 409d
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2025/06/20 lts (merge base) 83b4161a63b8 syz [report] INFO: task hung in uevent_show
2025/06/20 upstream (ToT) 5c8013ae2e86 syz [report] INFO: task hung in uhid_char_release
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in uevent_show usb 1 syz, C done 9704 722d 783d 28/29 fixed on 2024/10/22 11:56
linux-6.1 INFO: task hung in uevent_show origin:lts-only 1 syz, C inconclusive 72 3d05h 740d 0/3 upstream: reported C repro on 2024/07/26 06:22
upstream INFO: task hung in uevent_show (2) kernel 1 syz, C inconclusive 8325 395d 634d 29/29 fixed on 2025/07/17 21:22
linux-5.15 INFO: task hung in uevent_show origin:lts-only 1 syz, C inconclusive 71 19d 723d 0/3 upstream: reported C repro on 2024/08/12 05:03
▶ ▼ Last patch testing requests (6)
Created Duration User Patch Repo Result
2026/07/02 23:12 8m retest repro android16-6.12 error
2026/04/14 02:39 14m retest repro android16-6.12 report log
2026/02/03 00:50 15m retest repro android16-6.12 error
2025/11/24 22:55 5m retest repro android16-6.12 error
2025/09/15 22:10 11m retest repro android16-6.12 report log
2025/07/06 12:46 10m retest repro android16-6.12 report log

Sample crash report:
INFO: task udevd:109 blocked for more than 122 seconds.
      Not tainted 6.12.23-syzkaller-g30b14cdad458 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:udevd           state:D
 stack:0     pid:109   tgid:109   ppid:1      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5924 [inline]
 __schedule+0x145b/0x1f10 kernel/sched/core.c:7750
 __schedule_loop kernel/sched/core.c:7831 [inline]
 schedule+0xc6/0x240 kernel/sched/core.c:7846
 schedule_preempt_disabled+0x14/0x30 kernel/sched/core.c:7903
 __mutex_lock_common kernel/locking/mutex.c:692 [inline]
 __mutex_lock+0x836/0x1b60 kernel/locking/mutex.c:786
 device_lock include/linux/device.h:1025 [inline]
 uevent_show+0x194/0x400 drivers/base/core.c:2730
 kernfs_seq_show+0x12e/0x180 fs/kernfs/file.c:205
 seq_read_iter+0x50d/0xfe0 fs/seq_file.c:230
 kernfs_fop_read_iter+0x149/0x520 fs/kernfs/file.c:279
 ksys_read+0x141/0x250 fs/read_write.c:713
 __do_sys_read fs/read_write.c:723 [inline]
 __se_sys_read fs/read_write.c:721 [inline]
 __x64_sys_read+0x7f/0x90 fs/read_write.c:721
 x64_sys_call+0x2638/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x58/0xf0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f76b66a7407
RSP: 002b:00007ffeacd364a0 EFLAGS: 00000202 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007f76b6ddf880 RCX: 00007f76b66a7407
RDX: 0000000000001000 RSI: 000055bd60314030 RDI: 000000000000000c
RBP: 00007f76b67efff0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 000000000000000a
R13: 00007f76b67efea0 R14: 0000000000000000 R15: 000055bd60325fa0
 </TASK>
INFO: task syz.3.19:380 blocked for more than 123 seconds.
      Not tainted 6.12.23-syzkaller-g30b14cdad458 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.19        state:D
 stack:0     pid:380   tgid:380   ppid:367    flags:0x00000004
Call Trace:
 context_switch kernel/sched/core.c:5924 [inline]
 __schedule+0x145b/0x1f10 kernel/sched/core.c:7750
 __schedule_loop kernel/sched/core.c:7831 [inline]
 schedule+0xc6/0x240 kernel/sched/core.c:7846
 schedule_timeout+0xb2/0x3a0 kernel/time/timer.c:2595
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common+0x359/0x630 kernel/sched/completion.c:127
 wait_for_completion+0x1c/0x40 kernel/sched/completion.c:148
 __flush_work+0x6d2/0xac0 kernel/workqueue.c:4233
 __cancel_work_sync kernel/workqueue.c:4354 [inline]
 cancel_work_sync+0xac/0xe0 kernel/workqueue.c:4391
 uhid_dev_destroy drivers/hid/uhid.c:584 [inline]
 uhid_char_release+0xa7/0x600 drivers/hid/uhid.c:662
 __fput+0x1fb/0xa00 fs/file_table.c:431
 ____fput+0x20/0x30 fs/file_table.c:459
 task_work_run+0x1e0/0x250 kernel/task_work.c:240
 resume_user_mode_work+0x36/0x50 include/linux/resume_user_mode.h:50
 do_syscall_64+0x64/0xf0 arch/x86/entry/common.c:89
RIP: 0033:0x7f4e50f8e929
RAX: 0000000000000000 RBX: 0000000000006ee2 RCX: 00007f4e50f8e929
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000001 R09: 00000002f0ba66ef
R10: 00007f4e50e00000 R11: 0000000000000246 R12: 00007f4e511b5fac
R13: 00007f4e511b5fa0 R14: ffffffffffffffff R15: 0000000000000003
 </TASK>
INFO: task syz.1.17:384 blocked for more than 124 seconds.
      Not tainted 6.12.23-syzkaller-g30b14cdad458 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.17        state:D stack:0     pid:384   tgid:384   ppid:365    flags:0x00000004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5924 [inline]
 __schedule+0x145b/0x1f10 kernel/sched/core.c:7750
 __schedule_loop kernel/sched/core.c:7831 [inline]
 schedule+0xc6/0x240 kernel/sched/core.c:7846
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common+0x359/0x630 kernel/sched/completion.c:127
 wait_for_completion+0x1c/0x40 kernel/sched/completion.c:148
 __flush_work+0x6d2/0xac0 kernel/workqueue.c:4233
 __cancel_work_sync kernel/workqueue.c:4354 [inline]
 cancel_work_sync+0xac/0xe0 kernel/workqueue.c:4391
 uhid_dev_destroy drivers/hid/uhid.c:584 [inline]
 uhid_char_release+0xa7/0x600 drivers/hid/uhid.c:662
 __fput+0x1fb/0xa00 fs/file_table.c:431
 ____fput+0x20/0x30 fs/file_table.c:459
 task_work_run+0x1e0/0x250 kernel/task_work.c:240
 resume_user_mode_work+0x36/0x50 include/linux/resume_user_mode.h:50
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x64/0xb0 kernel/entry/common.c:218
 do_syscall_64+0x64/0xf0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f525878e929
RSP: 002b:00007ffe1ff6ba38 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 0000000000006f0f RCX: 00007f525878e929
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000001 R09: 000000021ff6bd2f
R10: 00007f5258600000 R11: 0000000000000246 R12: 00007f52589b5fac
R13: 00007f52589b5fa0 R14: ffffffffffffffff R15: 0000000000000003
 </TASK>
INFO: task syz.4.26:394 blocked for more than 125 seconds.
      Not tainted 6.12.23-syzkaller-g30b14cdad458 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common+0x359/0x630 kernel/sched/completion.c:127
 wait_for_completion+0x1c/0x40 kernel/sched/completion.c:148
 __flush_work+0x6d2/0xac0 kernel/workqueue.c:4233
 __cancel_work_sync kernel/workqueue.c:4354 [inline]
 cancel_work_sync+0xac/0xe0 kernel/workqueue.c:4391
 uhid_dev_destroy drivers/hid/uhid.c:584 [inline]
 uhid_char_release+0xa7/0x600 drivers/hid/uhid.c:662
 __fput+0x1fb/0xa00 fs/file_table.c:431
 ____fput+0x20/0x30 fs/file_table.c:459
 task_work_run+0x1e0/0x250 kernel/task_work.c:240
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x64/0xb0 kernel/entry/common.c:218
 do_syscall_64+0x64/0xf0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f823138e929
RAX: 0000000000000000 RBX: 0000000000006f55 RCX: 00007f823138e929
RBP: 0000000000000000 R08: 0000000000000001 R09: 000000021ef28d5f
R10: 00007f8231200000 R11: 0000000000000246 R12: 00007f82315b5fac
R13: 00007f82315b5fa0 R14: ffffffffffffffff R15: 0000000000000003
 </TASK>
INFO: task syz.0.29:397 blocked for more than 127 seconds.
      Not tainted 6.12.23-syzkaller-g30b14cdad458 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.29        state:D
 stack:0     pid:397   tgid:397   ppid:362    flags:0x00000004
Call Trace:
 <TASK>
 __schedule_loop kernel/sched/core.c:7831 [inline]
 schedule+0xc6/0x240 kernel/sched/core.c:7846
 schedule_timeout+0xb2/0x3a0 kernel/time/timer.c:2595
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common+0x359/0x630 kernel/sched/completion.c:127
 wait_for_completion+0x1c/0x40 kernel/sched/completion.c:148
 __flush_work+0x6d2/0xac0 kernel/workqueue.c:4233
 __cancel_work_sync kernel/workqueue.c:4354 [inline]
 cancel_work_sync+0xac/0xe0 kernel/workqueue.c:4391
 uhid_dev_destroy drivers/hid/uhid.c:584 [inline]
 uhid_char_release+0xa7/0x600 drivers/hid/uhid.c:662
 __fput+0x1fb/0xa00 fs/file_table.c:431
 ____fput+0x20/0x30 fs/file_table.c:459
 task_work_run+0x1e0/0x250 kernel/task_work.c:240
 resume_user_mode_work+0x36/0x50 include/linux/resume_user_mode.h:50
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x64/0xb0 kernel/entry/common.c:218
 do_syscall_64+0x64/0xf0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7fcb3998e929
RSP: 002b:00007ffd09b85be8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 0000000000006f79 RCX: 00007fcb3998e929
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000209b85edf
R10: 00007fcb39600000 R11: 0000000000000246 R12: 00007fcb39bb5fac
R13: 00007fcb39bb5fa0 R14: ffffffffffffffff R15: 0000000000000003
 </TASK>
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 37 Comm: khungtaskd Not tainted 6.12.23-syzkaller-g30b14cdad458 #0 c708c6bafa1314b3e84c64b9f03b67766970ebbd
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:94
 dump_stack+0x19/0x20 lib/dump_stack.c:129
 nmi_trigger_cpumask_backtrace+0x142/0x2c0 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:229 [inline]
 watchdog+0xd8f/0xed0 kernel/hung_task.c:385
 ret_from_fork+0x64/0xa0 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 535 Comm: kworker/0:10 Not tainted 6.12.23-syzkaller-g30b14cdad458 #0 c708c6bafa1314b3e84c64b9f03b67766970ebbd
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: events uhid_device_add_worker
RIP: 0010:delay_tsc+0x85/0xa0 arch/x86/lib/delay.c:96
Code: f9 66 90 eb cb e8 bb 28 86 fb eb dc 48 29 d7 0f 01 f9 66 90 48 89 d6 48 c1 e6 20 48 09 c6 45 89 c8 eb db 65 ff 0d 33 27 81 7a <74> 07 5d c3 cc cc cc cc cc e8 8d 28 86 fb 5d c3 cc cc cc cc cc 66
RSP: 0018:ffffc900020fedf8 EFLAGS: 00000002
RDX: 000000000000089a RSI: 0000005a99835aca RDI: 0000000000000899
RBP: ffffc900020fedf8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff8583c190 R12: ffffffff889d6d00
R13: 000000000000270d R14: ffffffff8897ac30 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055555c1dc4a8 CR3: 000000010b3b8000 CR4: 00000000003526b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __delay arch/x86/lib/delay.c:203 [inline]
 __const_udelay+0x77/0x90 arch/x86/lib/delay.c:217
 wait_for_lsr drivers/tty/serial/8250/8250_port.c:2075 [inline]
 fifo_wait_for_lsr drivers/tty/serial/8250/8250_port.c:3315 [inline]
 serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3337 [inline]
 serial8250_console_write+0x141c/0x2130 drivers/tty/serial/8250/8250_port.c:3422
 univ8250_console_write+0x6f/0xb0 drivers/tty/serial/8250/8250_core.c:396
 console_emit_next_record kernel/printk/printk.c:3134 [inline]
 console_flush_all+0x5e3/0xaa0 kernel/printk/printk.c:3222
 __console_flush_and_unlock kernel/printk/printk.c:3281 [inline]
 console_unlock+0xe9/0x270 kernel/printk/printk.c:3321
 __dev_printk+0x17f/0x1b0 drivers/base/core.c:4959
 _dev_warn+0x10b/0x160 drivers/base/core.c:5003
 hid_parser_main+0x84b/0xdc0 drivers/hid/hid-core.c:632
 hid_open_report+0x868/0x1110 drivers/hid/hid-core.c:1278
 __hid_device_probe drivers/hid/hid-core.c:2702 [inline]
 hid_device_probe+0x2c1/0x5d0 drivers/hid/hid-core.c:2739
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x2d3/0x890 drivers/base/dd.c:658
 __driver_probe_device+0x198/0x280 drivers/base/dd.c:800
 __device_attach_driver+0x2f1/0x4b0 drivers/base/dd.c:958
 __device_attach+0x2bd/0x3a0 drivers/base/dd.c:1030
 bus_probe_device+0x18b/0x270 drivers/base/bus.c:534
 device_add+0x80c/0xc00 drivers/base/core.c:3666
 uhid_device_add_worker+0x49/0xf0 drivers/hid/uhid.c:73
 worker_thread+0xc58/0x1250 kernel/workqueue.c:3400
 kthread+0x2c7/0x370 kernel/kthread.c:389
 </TASK>

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/06/19 15:21 android16-6.12 30b14cdad458 ed3e87f7 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in uevent_show
2025/06/22 11:26 android16-6.12 d9fd901baa98 d6cdfb8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in uevent_show
2025/06/22 07:28 android16-6.12 d9fd901baa98 d6cdfb8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in uevent_show
2025/06/21 08:05 android16-6.12 d9fd901baa98 d6cdfb8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in uevent_show
2025/06/21 07:10 android16-6.12 d9fd901baa98 d6cdfb8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in uevent_show
2025/06/21 00:49 android16-6.12 6c1c18fcb8b7 804b3919 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in uevent_show
2025/06/20 18:16 android16-6.12 6c1c18fcb8b7 804b3919 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in uevent_show
* Struck through repros no longer work on HEAD.