[v6.6] WARNING in call_timer_fn (2)
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syzbot
Mar 6, 2026, 6:46:20 PM (4 days ago) Mar 6
to syzkaller...@googlegroups.com
Hello,
syzbot found the following issue on:
HEAD commit: 4fc00fe35d46 Linux 6.6.129
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13084daa580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c5b35c4db8465904
dashboard link: https://syzkaller.appspot.com/bug?extid=660cf2a04050f8320a51
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b69a43016252/disk-4fc00fe3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/240ac8d2cf70/vmlinux-4fc00fe3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/67c7958e5edb/bzImage-4fc00fe3.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+660cf2...@syzkaller.appspotmail.com
------------[ cut here ]------------
WARNING: CPU: 1 PID: 5770 at kernel/workqueue.c:1745 is_chained_work kernel/workqueue.c:1691 [inline]
WARNING: CPU: 1 PID: 5770 at kernel/workqueue.c:1745 __queue_work+0xd49/0x1020 kernel/workqueue.c:1744
Modules linked in:
CPU: 1 PID: 5770 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:__queue_work+0xd49/0x1020 kernel/workqueue.c:1744
Code: 4c 89 f7 48 89 de 89 e9 e8 c4 e6 00 00 48 8b 5c 24 10 e9 10 ff ff ff e8 a5 ab 2f 00 eb 0c e8 9e ab 2f 00 eb 05 e8 97 ab 2f 00 <0f> 0b 48 83 c4 78 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 81 ab 2f 00
RSP: 0018:ffffc900001f0b10 EFLAGS: 00010046
RAX: ffffffff815770bb RBX: 0000000000000100 RCX: ffff888018bd8000
RDX: 0000000000000100 RSI: 0000000000000100 RDI: 0000000000000000
RBP: ffff8880311215c0 R08: ffffffff8e8aeeef R09: 1ffffffff1d15ddd
R10: dffffc0000000000 R11: fffffbfff1d15dde R12: 0000000000000008
R13: dffffc0000000000 R14: ffff88802fc8c9c0 R15: ffff888031121400
FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2cff0aa000 CR3: 0000000077b74000 CR4: 00000000003506e0
Call Trace:
<IRQ>
call_timer_fn+0x189/0x540 kernel/time/timer.c:1701
expire_timers kernel/time/timer.c:1747 [inline]
__run_timers+0x56d/0x800 kernel/time/timer.c:2023
run_timer_softirq+0x67/0xf0 kernel/time/timer.c:2036
handle_softirqs+0x280/0x820 kernel/softirq.c:578
__do_softirq kernel/softirq.c:612 [inline]
invoke_softirq kernel/softirq.c:452 [inline]
__irq_exit_rcu+0xd3/0x190 kernel/softirq.c:661
irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:finish_task_switch+0x26a/0x8f0 kernel/sched/core.c:5255
Code: 0f 84 33 01 00 00 48 85 db 0f 85 52 01 00 00 e9 de 04 00 00 4c 8b 75 d0 4c 89 e7 e8 00 54 31 09 e8 9b 23 30 00 fb 4c 8b 65 c0 <49> 8d bc 24 f8 15 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 28 84 c0
RSP: 0018:ffffc9000458f438 EFLAGS: 00000282
RAX: 661ab61198244d00 RBX: 0000000000000000 RCX: 661ab61198244d00
RDX: dffffc0000000000 RSI: ffffffff8acac960 RDI: ffffffff8b1c85a0
RBP: ffffc9000458f490 R08: ffffffff911c150f R09: 1ffffffff22382a1
R10: dffffc0000000000 R11: fffffbfff22382a2 R12: ffff888018bd8000
R13: dffffc0000000000 R14: ffff8880238dda00 R15: ffff8880b8f3cac8
context_switch kernel/sched/core.c:5384 [inline]
__schedule+0x155b/0x45a0 kernel/sched/core.c:6700
preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6867
preempt_schedule+0xc0/0xd0 kernel/sched/core.c:6891
preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
_raw_spin_unlock_irq+0x40/0x50 kernel/locking/spinlock.c:202
flush_workqueue_prep_pwqs+0x298/0x480 kernel/workqueue.c:3168
__flush_workqueue+0x492/0x13d0 kernel/workqueue.c:3234
drain_workqueue+0xd3/0x380 kernel/workqueue.c:3373
hci_dev_close_sync+0x4b9/0xfa0 net/bluetooth/hci_sync.c:5271
hci_dev_do_close net/bluetooth/hci_core.c:523 [inline]
hci_unregister_dev+0x21a/0x500 net/bluetooth/hci_core.c:2709
vhci_release+0x155/0x1a0 drivers/bluetooth/hci_vhci.c:691
__fput+0x234/0x970 fs/file_table.c:384
task_work_run+0x1d4/0x260 kernel/task_work.c:245
exit_task_work include/linux/task_work.h:43 [inline]
do_exit+0x95a/0x2460 kernel/exit.c:883
do_group_exit+0x21b/0x2d0 kernel/exit.c:1024
__do_sys_exit_group kernel/exit.c:1035 [inline]
__se_sys_exit_group kernel/exit.c:1033 [inline]
__x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1033
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ff59e59c799
Code: Unable to access opcode bytes at 0x7ff59e59c76f.
RSP: 002b:00007ffd2d472d58 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007ff59e632002 RCX: 00007ff59e59c799
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: 0000000000000016 R08: 0000000000000000 R09: 00007ff59e631f90
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffd2d474010
R13: 00007ff59e631f90 R14: 0000555585d024e8 R15: 00007ffd2d4761d0
</TASK>
----------------
Code disassembly (best guess):
0: 0f 84 33 01 00 00 je 0x139
6: 48 85 db test %rbx,%rbx
9: 0f 85 52 01 00 00 jne 0x161
f: e9 de 04 00 00 jmp 0x4f2
14: 4c 8b 75 d0 mov -0x30(%rbp),%r14
18: 4c 89 e7 mov %r12,%rdi
1b: e8 00 54 31 09 call 0x9315420
20: e8 9b 23 30 00 call 0x3023c0
25: fb sti
26: 4c 8b 65 c0 mov -0x40(%rbp),%r12
* 2a: 49 8d bc 24 f8 15 00 lea 0x15f8(%r12),%rdi <-- trapping instruction
31: 00
32: 48 89 f8 mov %rdi,%rax
35: 48 c1 e8 03 shr $0x3,%rax
39: 42 0f b6 04 28 movzbl (%rax,%r13,1),%eax
3e: 84 c0 test %al,%al
---
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: 4fc00fe35d46 Linux 6.6.129
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13084daa580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c5b35c4db8465904
dashboard link: https://syzkaller.appspot.com/bug?extid=660cf2a04050f8320a51
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b69a43016252/disk-4fc00fe3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/240ac8d2cf70/vmlinux-4fc00fe3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/67c7958e5edb/bzImage-4fc00fe3.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+660cf2...@syzkaller.appspotmail.com
------------[ cut here ]------------
WARNING: CPU: 1 PID: 5770 at kernel/workqueue.c:1745 is_chained_work kernel/workqueue.c:1691 [inline]
WARNING: CPU: 1 PID: 5770 at kernel/workqueue.c:1745 __queue_work+0xd49/0x1020 kernel/workqueue.c:1744
Modules linked in:
CPU: 1 PID: 5770 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:__queue_work+0xd49/0x1020 kernel/workqueue.c:1744
Code: 4c 89 f7 48 89 de 89 e9 e8 c4 e6 00 00 48 8b 5c 24 10 e9 10 ff ff ff e8 a5 ab 2f 00 eb 0c e8 9e ab 2f 00 eb 05 e8 97 ab 2f 00 <0f> 0b 48 83 c4 78 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 81 ab 2f 00
RSP: 0018:ffffc900001f0b10 EFLAGS: 00010046
RAX: ffffffff815770bb RBX: 0000000000000100 RCX: ffff888018bd8000
RDX: 0000000000000100 RSI: 0000000000000100 RDI: 0000000000000000
RBP: ffff8880311215c0 R08: ffffffff8e8aeeef R09: 1ffffffff1d15ddd
R10: dffffc0000000000 R11: fffffbfff1d15dde R12: 0000000000000008
R13: dffffc0000000000 R14: ffff88802fc8c9c0 R15: ffff888031121400
FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2cff0aa000 CR3: 0000000077b74000 CR4: 00000000003506e0
Call Trace:
<IRQ>
call_timer_fn+0x189/0x540 kernel/time/timer.c:1701
expire_timers kernel/time/timer.c:1747 [inline]
__run_timers+0x56d/0x800 kernel/time/timer.c:2023
run_timer_softirq+0x67/0xf0 kernel/time/timer.c:2036
handle_softirqs+0x280/0x820 kernel/softirq.c:578
__do_softirq kernel/softirq.c:612 [inline]
invoke_softirq kernel/softirq.c:452 [inline]
__irq_exit_rcu+0xd3/0x190 kernel/softirq.c:661
irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:finish_task_switch+0x26a/0x8f0 kernel/sched/core.c:5255
Code: 0f 84 33 01 00 00 48 85 db 0f 85 52 01 00 00 e9 de 04 00 00 4c 8b 75 d0 4c 89 e7 e8 00 54 31 09 e8 9b 23 30 00 fb 4c 8b 65 c0 <49> 8d bc 24 f8 15 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 28 84 c0
RSP: 0018:ffffc9000458f438 EFLAGS: 00000282
RAX: 661ab61198244d00 RBX: 0000000000000000 RCX: 661ab61198244d00
RDX: dffffc0000000000 RSI: ffffffff8acac960 RDI: ffffffff8b1c85a0
RBP: ffffc9000458f490 R08: ffffffff911c150f R09: 1ffffffff22382a1
R10: dffffc0000000000 R11: fffffbfff22382a2 R12: ffff888018bd8000
R13: dffffc0000000000 R14: ffff8880238dda00 R15: ffff8880b8f3cac8
context_switch kernel/sched/core.c:5384 [inline]
__schedule+0x155b/0x45a0 kernel/sched/core.c:6700
preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6867
preempt_schedule+0xc0/0xd0 kernel/sched/core.c:6891
preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
_raw_spin_unlock_irq+0x40/0x50 kernel/locking/spinlock.c:202
flush_workqueue_prep_pwqs+0x298/0x480 kernel/workqueue.c:3168
__flush_workqueue+0x492/0x13d0 kernel/workqueue.c:3234
drain_workqueue+0xd3/0x380 kernel/workqueue.c:3373
hci_dev_close_sync+0x4b9/0xfa0 net/bluetooth/hci_sync.c:5271
hci_dev_do_close net/bluetooth/hci_core.c:523 [inline]
hci_unregister_dev+0x21a/0x500 net/bluetooth/hci_core.c:2709
vhci_release+0x155/0x1a0 drivers/bluetooth/hci_vhci.c:691
__fput+0x234/0x970 fs/file_table.c:384
task_work_run+0x1d4/0x260 kernel/task_work.c:245
exit_task_work include/linux/task_work.h:43 [inline]
do_exit+0x95a/0x2460 kernel/exit.c:883
do_group_exit+0x21b/0x2d0 kernel/exit.c:1024
__do_sys_exit_group kernel/exit.c:1035 [inline]
__se_sys_exit_group kernel/exit.c:1033 [inline]
__x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1033
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ff59e59c799
Code: Unable to access opcode bytes at 0x7ff59e59c76f.
RSP: 002b:00007ffd2d472d58 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007ff59e632002 RCX: 00007ff59e59c799
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: 0000000000000016 R08: 0000000000000000 R09: 00007ff59e631f90
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffd2d474010
R13: 00007ff59e631f90 R14: 0000555585d024e8 R15: 00007ffd2d4761d0
</TASK>
----------------
Code disassembly (best guess):
0: 0f 84 33 01 00 00 je 0x139
6: 48 85 db test %rbx,%rbx
9: 0f 85 52 01 00 00 jne 0x161
f: e9 de 04 00 00 jmp 0x4f2
14: 4c 8b 75 d0 mov -0x30(%rbp),%r14
18: 4c 89 e7 mov %r12,%rdi
1b: e8 00 54 31 09 call 0x9315420
20: e8 9b 23 30 00 call 0x3023c0
25: fb sti
26: 4c 8b 65 c0 mov -0x40(%rbp),%r12
* 2a: 49 8d bc 24 f8 15 00 lea 0x15f8(%r12),%rdi <-- trapping instruction
31: 00
32: 48 89 f8 mov %rdi,%rax
35: 48 c1 e8 03 shr $0x3,%rax
39: 42 0f b6 04 28 movzbl (%rax,%r13,1),%eax
3e: 84 c0 test %al,%al
---
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
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