[v6.6] INFO: task hung in vt_ioctl
2 views
Skip to first unread message
syzbot
Nov 2, 2025, 9:54:30 AMNov 2
to syzkaller...@googlegroups.com
Hello,
syzbot found the following issue on:
HEAD commit: 0a805b6ea8cd Linux 6.6.116
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13db0012580000
kernel config: https://syzkaller.appspot.com/x/.config?x=12606d4b8832c7e4
dashboard link: https://syzkaller.appspot.com/bug?extid=06288a154a647232c259
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/13874446b4b2/disk-0a805b6e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/69a5e59e1ade/vmlinux-0a805b6e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/322c0711f976/bzImage-0a805b6e.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+06288a...@syzkaller.appspotmail.com
INFO: task syz.3.6378:26926 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.6378 state:D stack:27912 pid:26926 ppid:5793 flags:0x00004006
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5380 [inline]
__schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
schedule+0xbd/0x170 kernel/sched/core.c:6773
schedule_timeout+0x9b/0x280 kernel/time/timer.c:2143
___down_common kernel/locking/semaphore.c:229 [inline]
__down_common+0x308/0x640 kernel/locking/semaphore.c:250
down+0x80/0xd0 kernel/locking/semaphore.c:64
console_lock+0x145/0x1b0 kernel/printk/printk.c:2686
vt_ioctl+0x1b34/0x1d90 drivers/tty/vt/vt_ioctl.c:921
tty_ioctl+0x926/0xdd0 drivers/tty/tty_io.c:2779
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f03b418efc9
RSP: 002b:00007f03b4fc8038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f03b43e5fa0 RCX: 00007f03b418efc9
RDX: 0000200000001440 RSI: 0000000000005609 RDI: 0000000000000003
RBP: 00007f03b4211f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f03b43e6038 R14: 00007f03b43e5fa0 R15: 00007ffd4f124ea8
</TASK>
Showing all locks held in the system:
1 lock held by kthreadd/2:
2 locks held by kworker/0:0/8:
4 locks held by kworker/u4:1/12:
3 locks held by kworker/1:0/23:
1 lock held by khungtaskd/29:
#0: ffffffff8cd2fee0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
#0: ffffffff8cd2fee0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
#0: ffffffff8cd2fee0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
2 locks held by kworker/u4:3/48:
4 locks held by kworker/u4:4/73:
2 locks held by kworker/u4:5/987:
4 locks held by kworker/u4:7/1314:
3 locks held by kworker/u4:9/2924:
7 locks held by kworker/u4:10/2930:
1 lock held by klogd/5150:
6 locks held by udevd/5161:
3 locks held by dhcpcd/5456:
5 locks held by dhcpcd/5457:
2 locks held by getty/5553:
#0: ffff88802d9730a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc9000326e2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x425/0x1380 drivers/tty/n_tty.c:2217
2 locks held by syz-executor/5783:
3 locks held by syz-executor/5792:
2 locks held by syz-executor/5800:
2 locks held by kworker/0:4/5854:
4 locks held by kworker/u4:0/15012:
6 locks held by syz.0.6369/26889:
3 locks held by kworker/u4:8/26929:
3 locks held by kworker/u4:11/26930:
2 locks held by udevd/26935:
2 locks held by kworker/0:5/26936:
=============================================
NMI backtrace for cpu 1
CPU: 1 PID: 29 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
<TASK>
dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
nmi_cpu_backtrace+0x39b/0x3d0 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+0xf41/0xf80 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
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 2930 Comm: kworker/u4:10 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: events_unbound cfg80211_wiphy_work
RIP: 0010:check_preemption_disabled+0x3/0x110 lib/smp_processor_id.c:13
Code: ff ff ff cc cc cc cc f3 0f 1e fa 48 c7 c7 a0 6a fc 8a 48 c7 c6 e0 6a fc 8a eb 0c 66 2e 0f 1f 84 00 00 00 00 00 66 90 55 41 57 <41> 56 53 48 83 ec 10 65 48 8b 04 25 28 00 00 00 48 89 44 24 08 65
RSP: 0018:ffffc90000007348 EFLAGS: 00000246
RAX: 1ffff11005a348d1 RBX: ffff88802d1a4000 RCX: ffff88802be59e00
RDX: 0000000000000100 RSI: ffffffff8afc6ae0 RDI: ffffffff8afc6aa0
RBP: ffffc90000007550 R08: ffffffff8e4a8d6f R09: 1ffffffff1c951ad
R10: dffffc0000000000 R11: fffffbfff1c951ae R12: 0000000000000038
R13: 0000607f46e30180 R14: ffff8880605a0000 R15: ffff88802d1a4688
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd4c5b9d7c CR3: 0000000079606000 CR4: 00000000003506f0
Call Trace:
<IRQ>
dev_sw_netstats_rx_add include/linux/netdevice.h:2766 [inline]
br_pass_frame_up+0x7c/0x410 net/bridge/br_input.c:39
br_handle_frame_finish+0x146c/0x1920 net/bridge/br_input.c:221
br_nf_hook_thresh+0x3b6/0x480 net/bridge/br_netfilter_hooks.c:1184
br_nf_pre_routing_finish_ipv6+0x9e3/0xd90 net/bridge/br_netfilter_ipv6.c:-1
NF_HOOK include/linux/netfilter.h:304 [inline]
br_nf_pre_routing_ipv6+0x34d/0x680 net/bridge/br_netfilter_ipv6.c:184
nf_hook_entry_hookfn include/linux/netfilter.h:144 [inline]
nf_hook_bridge_pre net/bridge/br_input.c:277 [inline]
br_handle_frame+0x96b/0x1480 net/bridge/br_input.c:424
__netif_receive_skb_core+0xf6b/0x3ac0 net/core/dev.c:5502
__netif_receive_skb_one_core net/core/dev.c:5606 [inline]
__netif_receive_skb+0x74/0x290 net/core/dev.c:5722
process_backlog+0x380/0x6e0 net/core/dev.c:6050
__napi_poll+0xc0/0x460 net/core/dev.c:6612
napi_poll net/core/dev.c:6679 [inline]
net_rx_action+0x5ea/0xbf0 net/core/dev.c:6815
handle_softirqs+0x280/0x820 kernel/softirq.c:578
do_softirq+0xed/0x180 kernel/softirq.c:479
</IRQ>
<TASK>
__local_bh_enable_ip+0x178/0x1c0 kernel/softirq.c:406
spin_unlock_bh include/linux/spinlock.h:396 [inline]
cfg80211_inform_single_bss_frame_data net/wireless/scan.c:2988 [inline]
cfg80211_inform_bss_frame_data+0xb3b/0x12b0 net/wireless/scan.c:3013
ieee80211_bss_info_update+0x70b/0x930 net/mac80211/scan.c:211
ieee80211_rx_bss_info net/mac80211/ibss.c:1124 [inline]
ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1613 [inline]
ieee80211_ibss_rx_queued_mgmt+0x17c9/0x2ac0 net/mac80211/ibss.c:1642
ieee80211_iface_process_skb net/mac80211/iface.c:1643 [inline]
ieee80211_iface_work+0x717/0xc70 net/mac80211/iface.c:1697
cfg80211_wiphy_work+0x225/0x260 net/wireless/core.c:437
process_one_work kernel/workqueue.c:2634 [inline]
process_scheduled_works+0xa45/0x15b0 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
</TASK>
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
syzbot found the following issue on:
HEAD commit: 0a805b6ea8cd Linux 6.6.116
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13db0012580000
kernel config: https://syzkaller.appspot.com/x/.config?x=12606d4b8832c7e4
dashboard link: https://syzkaller.appspot.com/bug?extid=06288a154a647232c259
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/13874446b4b2/disk-0a805b6e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/69a5e59e1ade/vmlinux-0a805b6e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/322c0711f976/bzImage-0a805b6e.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+06288a...@syzkaller.appspotmail.com
INFO: task syz.3.6378:26926 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.6378 state:D stack:27912 pid:26926 ppid:5793 flags:0x00004006
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5380 [inline]
__schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
schedule+0xbd/0x170 kernel/sched/core.c:6773
schedule_timeout+0x9b/0x280 kernel/time/timer.c:2143
___down_common kernel/locking/semaphore.c:229 [inline]
__down_common+0x308/0x640 kernel/locking/semaphore.c:250
down+0x80/0xd0 kernel/locking/semaphore.c:64
console_lock+0x145/0x1b0 kernel/printk/printk.c:2686
vt_ioctl+0x1b34/0x1d90 drivers/tty/vt/vt_ioctl.c:921
tty_ioctl+0x926/0xdd0 drivers/tty/tty_io.c:2779
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f03b418efc9
RSP: 002b:00007f03b4fc8038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f03b43e5fa0 RCX: 00007f03b418efc9
RDX: 0000200000001440 RSI: 0000000000005609 RDI: 0000000000000003
RBP: 00007f03b4211f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f03b43e6038 R14: 00007f03b43e5fa0 R15: 00007ffd4f124ea8
</TASK>
Showing all locks held in the system:
1 lock held by kthreadd/2:
2 locks held by kworker/0:0/8:
4 locks held by kworker/u4:1/12:
3 locks held by kworker/1:0/23:
1 lock held by khungtaskd/29:
#0: ffffffff8cd2fee0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
#0: ffffffff8cd2fee0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
#0: ffffffff8cd2fee0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
2 locks held by kworker/u4:3/48:
4 locks held by kworker/u4:4/73:
2 locks held by kworker/u4:5/987:
4 locks held by kworker/u4:7/1314:
3 locks held by kworker/u4:9/2924:
7 locks held by kworker/u4:10/2930:
1 lock held by klogd/5150:
6 locks held by udevd/5161:
3 locks held by dhcpcd/5456:
5 locks held by dhcpcd/5457:
2 locks held by getty/5553:
#0: ffff88802d9730a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc9000326e2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x425/0x1380 drivers/tty/n_tty.c:2217
2 locks held by syz-executor/5783:
3 locks held by syz-executor/5792:
2 locks held by syz-executor/5800:
2 locks held by kworker/0:4/5854:
4 locks held by kworker/u4:0/15012:
6 locks held by syz.0.6369/26889:
3 locks held by kworker/u4:8/26929:
3 locks held by kworker/u4:11/26930:
2 locks held by udevd/26935:
2 locks held by kworker/0:5/26936:
=============================================
NMI backtrace for cpu 1
CPU: 1 PID: 29 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
<TASK>
dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
nmi_cpu_backtrace+0x39b/0x3d0 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+0xf41/0xf80 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
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 2930 Comm: kworker/u4:10 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: events_unbound cfg80211_wiphy_work
RIP: 0010:check_preemption_disabled+0x3/0x110 lib/smp_processor_id.c:13
Code: ff ff ff cc cc cc cc f3 0f 1e fa 48 c7 c7 a0 6a fc 8a 48 c7 c6 e0 6a fc 8a eb 0c 66 2e 0f 1f 84 00 00 00 00 00 66 90 55 41 57 <41> 56 53 48 83 ec 10 65 48 8b 04 25 28 00 00 00 48 89 44 24 08 65
RSP: 0018:ffffc90000007348 EFLAGS: 00000246
RAX: 1ffff11005a348d1 RBX: ffff88802d1a4000 RCX: ffff88802be59e00
RDX: 0000000000000100 RSI: ffffffff8afc6ae0 RDI: ffffffff8afc6aa0
RBP: ffffc90000007550 R08: ffffffff8e4a8d6f R09: 1ffffffff1c951ad
R10: dffffc0000000000 R11: fffffbfff1c951ae R12: 0000000000000038
R13: 0000607f46e30180 R14: ffff8880605a0000 R15: ffff88802d1a4688
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd4c5b9d7c CR3: 0000000079606000 CR4: 00000000003506f0
Call Trace:
<IRQ>
dev_sw_netstats_rx_add include/linux/netdevice.h:2766 [inline]
br_pass_frame_up+0x7c/0x410 net/bridge/br_input.c:39
br_handle_frame_finish+0x146c/0x1920 net/bridge/br_input.c:221
br_nf_hook_thresh+0x3b6/0x480 net/bridge/br_netfilter_hooks.c:1184
br_nf_pre_routing_finish_ipv6+0x9e3/0xd90 net/bridge/br_netfilter_ipv6.c:-1
NF_HOOK include/linux/netfilter.h:304 [inline]
br_nf_pre_routing_ipv6+0x34d/0x680 net/bridge/br_netfilter_ipv6.c:184
nf_hook_entry_hookfn include/linux/netfilter.h:144 [inline]
nf_hook_bridge_pre net/bridge/br_input.c:277 [inline]
br_handle_frame+0x96b/0x1480 net/bridge/br_input.c:424
__netif_receive_skb_core+0xf6b/0x3ac0 net/core/dev.c:5502
__netif_receive_skb_one_core net/core/dev.c:5606 [inline]
__netif_receive_skb+0x74/0x290 net/core/dev.c:5722
process_backlog+0x380/0x6e0 net/core/dev.c:6050
__napi_poll+0xc0/0x460 net/core/dev.c:6612
napi_poll net/core/dev.c:6679 [inline]
net_rx_action+0x5ea/0xbf0 net/core/dev.c:6815
handle_softirqs+0x280/0x820 kernel/softirq.c:578
do_softirq+0xed/0x180 kernel/softirq.c:479
</IRQ>
<TASK>
__local_bh_enable_ip+0x178/0x1c0 kernel/softirq.c:406
spin_unlock_bh include/linux/spinlock.h:396 [inline]
cfg80211_inform_single_bss_frame_data net/wireless/scan.c:2988 [inline]
cfg80211_inform_bss_frame_data+0xb3b/0x12b0 net/wireless/scan.c:3013
ieee80211_bss_info_update+0x70b/0x930 net/mac80211/scan.c:211
ieee80211_rx_bss_info net/mac80211/ibss.c:1124 [inline]
ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1613 [inline]
ieee80211_ibss_rx_queued_mgmt+0x17c9/0x2ac0 net/mac80211/ibss.c:1642
ieee80211_iface_process_skb net/mac80211/iface.c:1643 [inline]
ieee80211_iface_work+0x717/0xc70 net/mac80211/iface.c:1697
cfg80211_wiphy_work+0x225/0x260 net/wireless/core.c:437
process_one_work kernel/workqueue.c:2634 [inline]
process_scheduled_works+0xa45/0x15b0 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
</TASK>
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
Reply all
Reply to author
Forward
0 new messages