[v6.6] INFO: task hung in usbdev_open
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syzbot
Dec 23, 2025, 12:09:22 PM (yesterday) Dec 23
to syzkaller...@googlegroups.com
Hello,
syzbot found the following issue on:
HEAD commit: 5fa4793a2d2d Linux 6.6.119
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=112b5f1a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=691a6769a86ac817
dashboard link: https://syzkaller.appspot.com/bug?extid=59ec26cedb2b42e7be25
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/63699875f1dd/disk-5fa4793a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8506652fcb6f/vmlinux-5fa4793a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1b30ceed1710/bzImage-5fa4793a.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+59ec26...@syzkaller.appspotmail.com
INFO: task syz.1.1603:10591 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.1603 state:D stack:24392 pid:10591 ppid:5764 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_preempt_disabled+0x13/0x20 kernel/sched/core.c:6832
__mutex_lock_common kernel/locking/mutex.c:679 [inline]
__mutex_lock+0x6b7/0xcc0 kernel/locking/mutex.c:747
device_lock include/linux/device.h:995 [inline]
usbdev_open+0x16f/0x760 drivers/usb/core/devio.c:1051
chrdev_open+0x59e/0x670 fs/char_dev.c:414
do_dentry_open+0x8c6/0x1500 fs/open.c:929
do_open fs/namei.c:3640 [inline]
path_openat+0x274b/0x3190 fs/namei.c:3797
do_filp_open+0x1c5/0x3d0 fs/namei.c:3824
do_sys_openat2+0x12c/0x1c0 fs/open.c:1421
do_sys_open fs/open.c:1436 [inline]
__do_sys_openat fs/open.c:1452 [inline]
__se_sys_openat fs/open.c:1447 [inline]
__x64_sys_openat+0x139/0x160 fs/open.c:1447
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: 0033:0x7ff62a18df90
RSP: 002b:00007ff62b040b70 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000080100 RCX: 00007ff62a18df90
RDX: 0000000000080100 RSI: 00007ff62b040c10 RDI: 00000000ffffff9c
RBP: 00007ff62b040c10 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: cccccccccccccccd
R13: 00007ff62a3e6038 R14: 00007ff62a3e5fa0 R15: 00007ffde91b6818
</TASK>
Showing all locks held in the system:
5 locks held by kworker/u4:0/11:
#0: ffff888017873938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#0: ffff888017873938 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#1: ffffc90000107d00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#1: ffffc90000107d00 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#2: ffffffff8dfa8610 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x136/0xb90 net/core/net_namespace.c:606
#3: ffff88805b8f3250 (&devlink->lock_key#9){+.+.}-{3:3}, at: devl_lock net/devlink/core.c:60 [inline]
#3: ffff88805b8f3250 (&devlink->lock_key#9){+.+.}-{3:3}, at: devlink_pernet_pre_exit+0xe1/0x340 net/devlink/core.c:285
#4: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: nsim_destroy+0x3f/0x180 drivers/net/netdevsim/netdev.c:417
3 locks held by kworker/u4:1/12:
#0: ffff88802c695d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#0: ffff88802c695d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#1: ffffc90000117d00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#1: ffffc90000117d00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#2: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xd0/0x14e0 net/ipv6/addrconf.c:4158
1 lock held by khungtaskd/29:
#0: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
#0: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
#0: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
2 locks held by kworker/u4:5/62:
2 locks held by getty/5523:
#0: ffff88802d90c0a0 (&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
11 locks held by kworker/0:3/5799:
2 locks held by kworker/1:6/6986:
#0: ffff888017872538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#0: ffff888017872538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#1: ffffc90003947d00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#1: ffffc90003947d00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
4 locks held by udevd/9714:
#0: ffff88802e537540 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0xb1/0xd50 fs/seq_file.c:182
#1: ffff88805e3e3088 (&of->mutex){+.+.}-{3:3}, at: kernfs_seq_start+0x5c/0x410 fs/kernfs/file.c:172
#2: ffff88805f334e90 (kn->active#25){++++}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
#2: ffff88805f334e90 (kn->active#25){++++}-{0:0}, at: kernfs_seq_start+0xb2/0x410 fs/kernfs/file.c:173
#3: ffff888019290190 (&dev->mutex){....}-{3:3}, at: device_lock_interruptible include/linux/device.h:1000 [inline]
#3: ffff888019290190 (&dev->mutex){....}-{3:3}, at: manufacturer_show+0x26/0xa0 drivers/usb/core/sysfs.c:142
1 lock held by syz.1.1603/10591:
#0: ffff888142b4c190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:995 [inline]
#0: ffff888142b4c190 (&dev->mutex){....}-{3:3}, at: usbdev_open+0x16f/0x760 drivers/usb/core/devio.c:1051
2 locks held by syz-executor/11886:
#0: ffffffff8e019f10 (cb_lock){++++}-{3:3}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1074
#1: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: nl80211_pre_doit+0x5f/0x930 net/wireless/nl80211.c:16515
3 locks held by kworker/u4:14/11936:
#0: ffff888017871538 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#0: ffff888017871538 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#1: ffffc90004a6fd00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#1: ffffc90004a6fd00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#2: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:286
1 lock held by syz-executor/12012:
#0: ffffffff8cd358f8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:324 [inline]
#0: ffffffff8cd358f8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x360/0x830 kernel/rcu/tree_exp.h:1004
1 lock held by syz-executor/12159:
#0: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
#0: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x76f/0xf10 net/core/rtnetlink.c:6469
2 locks held by syz.7.1952/12162:
#0: ffffffff8d7da028 (ppp_mutex){+.+.}-{3:3}, at: ppp_ioctl+0xce/0x1980 drivers/net/ppp/ppp_generic.c:739
#1: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: ppp_create_interface drivers/net/ppp/ppp_generic.c:3360 [inline]
#1: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: ppp_unattached_ioctl drivers/net/ppp/ppp_generic.c:1070 [inline]
#1: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: ppp_ioctl+0x698/0x1980 drivers/net/ppp/ppp_generic.c:743
1 lock held by syz.7.1952/12163:
#0: ffffffff8d7da028 (ppp_mutex){+.+.}-{3:3}, at: ppp_ioctl+0xce/0x1980 drivers/net/ppp/ppp_generic.c:739
1 lock held by syz.7.1952/12164:
#0: ffffffff8d7da028 (ppp_mutex){+.+.}-{3:3}, at: ppp_ioctl+0xce/0x1980 drivers/net/ppp/ppp_generic.c:739
=============================================
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 10/25/2025
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: 12012 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:page_ext_data include/linux/page_ext.h:87 [inline]
RIP: 0010:get_page_table_check mm/page_table_check.c:56 [inline]
RIP: 0010:__page_table_check_zero+0x1aa/0x4b0 mm/page_table_check.c:154
Code: dc 44 89 f9 49 d3 ec 31 ff 4c 89 e6 e8 0f c2 9d ff 4d 85 e4 0f 85 f2 00 00 00 4d 85 f6 0f 84 32 01 00 00 4c 8b 25 d6 c7 fc 0a <4d> 01 f4 4c 89 e7 be 04 00 00 00 e8 56 2d f5 ff 4c 89 e0 48 c1 e8
RSP: 0018:ffffc90003427838 EFLAGS: 00000282
RAX: ffffffff81e7d2f1 RBX: 0000000000000000 RCX: ffff88802dadda00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: dffffc0000000000 R08: dffffc0000000000 R09: 1ffffffff21b28a0
R10: dffffc0000000000 R11: fffffbfff21b28a1 R12: 0000000000000040
R13: 1ffffffff2de0b30 R14: ffff88801a8c7440 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb610772a60 CR3: 000000000cb30000 CR4: 00000000003506f0
Call Trace:
<TASK>
page_table_check_free include/linux/page_table_check.h:41 [inline]
free_pages_prepare mm/page_alloc.c:1155 [inline]
free_unref_page_prepare+0x7e1/0x8e0 mm/page_alloc.c:2336
free_unref_page+0x32/0x2e0 mm/page_alloc.c:2429
vfree+0x1a6/0x320 mm/vmalloc.c:2868
kcov_put kernel/kcov.c:438 [inline]
kcov_close+0x2b/0x50 kernel/kcov.c:534
__fput+0x234/0x970 fs/file_table.c:384
task_work_run+0x1ce/0x250 kernel/task_work.c:239
exit_task_work include/linux/task_work.h:43 [inline]
do_exit+0x90b/0x23c0 kernel/exit.c:883
do_group_exit+0x21b/0x2d0 kernel/exit.c:1024
get_signal+0x12fc/0x1400 kernel/signal.c:2902
arch_do_signal_or_restart+0x9c/0x7b0 arch/x86/kernel/signal.c:310
exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
__syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f4f553915dc
Code: Unable to access opcode bytes at 0x7f4f553915b2.
RSP: 002b:00007fff9d611170 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: 0000000000000028 RBX: 00007f4f56114620 RCX: 00007f4f553915dc
RDX: 0000000000000028 RSI: 00007f4f56114670 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007fff9d6111c4 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f4f56114670 R15: 0000000000000000
</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: 5fa4793a2d2d Linux 6.6.119
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=112b5f1a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=691a6769a86ac817
dashboard link: https://syzkaller.appspot.com/bug?extid=59ec26cedb2b42e7be25
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/63699875f1dd/disk-5fa4793a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8506652fcb6f/vmlinux-5fa4793a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1b30ceed1710/bzImage-5fa4793a.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+59ec26...@syzkaller.appspotmail.com
INFO: task syz.1.1603:10591 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.1603 state:D stack:24392 pid:10591 ppid:5764 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_preempt_disabled+0x13/0x20 kernel/sched/core.c:6832
__mutex_lock_common kernel/locking/mutex.c:679 [inline]
__mutex_lock+0x6b7/0xcc0 kernel/locking/mutex.c:747
device_lock include/linux/device.h:995 [inline]
usbdev_open+0x16f/0x760 drivers/usb/core/devio.c:1051
chrdev_open+0x59e/0x670 fs/char_dev.c:414
do_dentry_open+0x8c6/0x1500 fs/open.c:929
do_open fs/namei.c:3640 [inline]
path_openat+0x274b/0x3190 fs/namei.c:3797
do_filp_open+0x1c5/0x3d0 fs/namei.c:3824
do_sys_openat2+0x12c/0x1c0 fs/open.c:1421
do_sys_open fs/open.c:1436 [inline]
__do_sys_openat fs/open.c:1452 [inline]
__se_sys_openat fs/open.c:1447 [inline]
__x64_sys_openat+0x139/0x160 fs/open.c:1447
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: 0033:0x7ff62a18df90
RSP: 002b:00007ff62b040b70 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000080100 RCX: 00007ff62a18df90
RDX: 0000000000080100 RSI: 00007ff62b040c10 RDI: 00000000ffffff9c
RBP: 00007ff62b040c10 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: cccccccccccccccd
R13: 00007ff62a3e6038 R14: 00007ff62a3e5fa0 R15: 00007ffde91b6818
</TASK>
Showing all locks held in the system:
5 locks held by kworker/u4:0/11:
#0: ffff888017873938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#0: ffff888017873938 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#1: ffffc90000107d00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#1: ffffc90000107d00 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#2: ffffffff8dfa8610 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x136/0xb90 net/core/net_namespace.c:606
#3: ffff88805b8f3250 (&devlink->lock_key#9){+.+.}-{3:3}, at: devl_lock net/devlink/core.c:60 [inline]
#3: ffff88805b8f3250 (&devlink->lock_key#9){+.+.}-{3:3}, at: devlink_pernet_pre_exit+0xe1/0x340 net/devlink/core.c:285
#4: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: nsim_destroy+0x3f/0x180 drivers/net/netdevsim/netdev.c:417
3 locks held by kworker/u4:1/12:
#0: ffff88802c695d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#0: ffff88802c695d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#1: ffffc90000117d00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#1: ffffc90000117d00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#2: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xd0/0x14e0 net/ipv6/addrconf.c:4158
1 lock held by khungtaskd/29:
#0: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
#0: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
#0: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
2 locks held by kworker/u4:5/62:
2 locks held by getty/5523:
#0: ffff88802d90c0a0 (&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
11 locks held by kworker/0:3/5799:
2 locks held by kworker/1:6/6986:
#0: ffff888017872538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#0: ffff888017872538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#1: ffffc90003947d00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#1: ffffc90003947d00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
4 locks held by udevd/9714:
#0: ffff88802e537540 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0xb1/0xd50 fs/seq_file.c:182
#1: ffff88805e3e3088 (&of->mutex){+.+.}-{3:3}, at: kernfs_seq_start+0x5c/0x410 fs/kernfs/file.c:172
#2: ffff88805f334e90 (kn->active#25){++++}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
#2: ffff88805f334e90 (kn->active#25){++++}-{0:0}, at: kernfs_seq_start+0xb2/0x410 fs/kernfs/file.c:173
#3: ffff888019290190 (&dev->mutex){....}-{3:3}, at: device_lock_interruptible include/linux/device.h:1000 [inline]
#3: ffff888019290190 (&dev->mutex){....}-{3:3}, at: manufacturer_show+0x26/0xa0 drivers/usb/core/sysfs.c:142
1 lock held by syz.1.1603/10591:
#0: ffff888142b4c190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:995 [inline]
#0: ffff888142b4c190 (&dev->mutex){....}-{3:3}, at: usbdev_open+0x16f/0x760 drivers/usb/core/devio.c:1051
2 locks held by syz-executor/11886:
#0: ffffffff8e019f10 (cb_lock){++++}-{3:3}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1074
#1: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: nl80211_pre_doit+0x5f/0x930 net/wireless/nl80211.c:16515
3 locks held by kworker/u4:14/11936:
#0: ffff888017871538 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#0: ffff888017871538 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#1: ffffc90004a6fd00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
#1: ffffc90004a6fd00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
#2: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:286
1 lock held by syz-executor/12012:
#0: ffffffff8cd358f8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:324 [inline]
#0: ffffffff8cd358f8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x360/0x830 kernel/rcu/tree_exp.h:1004
1 lock held by syz-executor/12159:
#0: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
#0: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x76f/0xf10 net/core/rtnetlink.c:6469
2 locks held by syz.7.1952/12162:
#0: ffffffff8d7da028 (ppp_mutex){+.+.}-{3:3}, at: ppp_ioctl+0xce/0x1980 drivers/net/ppp/ppp_generic.c:739
#1: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: ppp_create_interface drivers/net/ppp/ppp_generic.c:3360 [inline]
#1: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: ppp_unattached_ioctl drivers/net/ppp/ppp_generic.c:1070 [inline]
#1: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: ppp_ioctl+0x698/0x1980 drivers/net/ppp/ppp_generic.c:743
1 lock held by syz.7.1952/12163:
#0: ffffffff8d7da028 (ppp_mutex){+.+.}-{3:3}, at: ppp_ioctl+0xce/0x1980 drivers/net/ppp/ppp_generic.c:739
1 lock held by syz.7.1952/12164:
#0: ffffffff8d7da028 (ppp_mutex){+.+.}-{3:3}, at: ppp_ioctl+0xce/0x1980 drivers/net/ppp/ppp_generic.c:739
=============================================
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 10/25/2025
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: 12012 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:page_ext_data include/linux/page_ext.h:87 [inline]
RIP: 0010:get_page_table_check mm/page_table_check.c:56 [inline]
RIP: 0010:__page_table_check_zero+0x1aa/0x4b0 mm/page_table_check.c:154
Code: dc 44 89 f9 49 d3 ec 31 ff 4c 89 e6 e8 0f c2 9d ff 4d 85 e4 0f 85 f2 00 00 00 4d 85 f6 0f 84 32 01 00 00 4c 8b 25 d6 c7 fc 0a <4d> 01 f4 4c 89 e7 be 04 00 00 00 e8 56 2d f5 ff 4c 89 e0 48 c1 e8
RSP: 0018:ffffc90003427838 EFLAGS: 00000282
RAX: ffffffff81e7d2f1 RBX: 0000000000000000 RCX: ffff88802dadda00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: dffffc0000000000 R08: dffffc0000000000 R09: 1ffffffff21b28a0
R10: dffffc0000000000 R11: fffffbfff21b28a1 R12: 0000000000000040
R13: 1ffffffff2de0b30 R14: ffff88801a8c7440 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb610772a60 CR3: 000000000cb30000 CR4: 00000000003506f0
Call Trace:
<TASK>
page_table_check_free include/linux/page_table_check.h:41 [inline]
free_pages_prepare mm/page_alloc.c:1155 [inline]
free_unref_page_prepare+0x7e1/0x8e0 mm/page_alloc.c:2336
free_unref_page+0x32/0x2e0 mm/page_alloc.c:2429
vfree+0x1a6/0x320 mm/vmalloc.c:2868
kcov_put kernel/kcov.c:438 [inline]
kcov_close+0x2b/0x50 kernel/kcov.c:534
__fput+0x234/0x970 fs/file_table.c:384
task_work_run+0x1ce/0x250 kernel/task_work.c:239
exit_task_work include/linux/task_work.h:43 [inline]
do_exit+0x90b/0x23c0 kernel/exit.c:883
do_group_exit+0x21b/0x2d0 kernel/exit.c:1024
get_signal+0x12fc/0x1400 kernel/signal.c:2902
arch_do_signal_or_restart+0x9c/0x7b0 arch/x86/kernel/signal.c:310
exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
__syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f4f553915dc
Code: Unable to access opcode bytes at 0x7f4f553915b2.
RSP: 002b:00007fff9d611170 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: 0000000000000028 RBX: 00007f4f56114620 RCX: 00007f4f553915dc
RDX: 0000000000000028 RSI: 00007f4f56114670 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007fff9d6111c4 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f4f56114670 R15: 0000000000000000
</TASK>
---
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