[v5.15] WARNING in call_timer_fn (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 91d48252ad4b Linux 5.15.202
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=154b7bd6580000
kernel config: https://syzkaller.appspot.com/x/.config?x=353ae28c40b35af5
dashboard link: https://syzkaller.appspot.com/bug?extid=e4764f072c4253c1444f
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/74e75dfcb812/disk-91d48252.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/bfa72aab00f2/vmlinux-91d48252.xz
kernel image: https://storage.googleapis.com/syzbot-assets/47ea72d1c7dc/bzImage-91d48252.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e4764f...@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 1 PID: 4399 at kernel/workqueue.c:1453 __queue_work+0xc04/0xd50 kernel/workqueue.c:1453
Modules linked in:
CPU: 1 PID: 4399 Comm: kworker/u4:9 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: events_unbound linkwatch_event
RIP: 0010:__queue_work+0xc04/0xd50 kernel/workqueue.c:1453
Code: fc ff ff 48 8b 4c 24 08 80 e1 07 80 c1 03 38 c1 0f 8c 13 fd ff ff 48 8b 7c 24 08 e8 d6 31 70 00 e9 04 fd ff ff e8 7c 26 2b 00 <0f> 0b 48 83 c4 50 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 66 26 2b 00
RSP: 0018:ffffc90000dd0b18 EFLAGS: 00010046
RAX: ffffffff814dfa94 RBX: 0000000000010000 RCX: ffff88802b873b80
RDX: 0000000000000100 RSI: 0000000000000100 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffff8d89e36f R09: 1ffffffff1b13c6d
R10: dffffc0000000000 R11: fffffbfff1b13c6e R12: ffff88807a6d2180
R13: ffff8880257341c0 R14: ffff888025734000 R15: 0000000000000008
FS: 0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f80a6604000 CR3: 0000000067277000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
call_timer_fn+0x17b/0x540 kernel/time/timer.c:1648
expire_timers kernel/time/timer.c:1694 [inline]
__run_timers+0x569/0x800 kernel/time/timer.c:1970
run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1983
handle_softirqs+0x339/0x830 kernel/softirq.c:576
__do_softirq kernel/softirq.c:610 [inline]
invoke_softirq kernel/softirq.c:450 [inline]
__irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659
irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:instrument_atomic_read include/linux/instrumented.h:71 [inline]
RIP: 0010:atomic_long_read include/linux/atomic/atomic-instrumented.h:1183 [inline]
RIP: 0010:__mutex_owner kernel/locking/mutex.c:78 [inline]
RIP: 0010:mutex_spin_on_owner+0x283/0x380 kernel/locking/mutex.c:352
Code: ef be 08 00 00 00 e8 5c ee 61 00 42 80 3c 3b 00 74 08 4c 89 ef e8 bd ec 61 00 49 f7 45 00 01 00 00 00 0f 85 8b 00 00 00 f3 90 <4c> 89 ef be 08 00 00 00 e8 30 ee 61 00 42 80 3c 3b 00 0f 84 84 fe
RSP: 0018:ffffc90002def9b0 EFLAGS: 00000246
RAX: ffff8880b9000000 RBX: 1ffffffff1a8795c RCX: ffffffff815c3ea8
RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000000
RBP: ffffffff8d43cb30 R08: ffff88802b873b87 R09: 1ffff1100570e770
R10: dffffc0000000000 R11: ffffed100570e771 R12: ffff88802c1e0000
R13: ffffffff8d43cae0 R14: ffffffff8d43cb30 R15: dffffc0000000000
mutex_optimistic_spin+0x38/0x300 kernel/locking/mutex.c:469
__mutex_lock_common+0xda2/0x2400 kernel/locking/mutex.c:680
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
linkwatch_event+0xa/0x50 net/core/link_watch.c:251
process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
----------------
Code disassembly (best guess):
0: ef out %eax,(%dx)
1: be 08 00 00 00 mov $0x8,%esi
6: e8 5c ee 61 00 call 0x61ee67
b: 42 80 3c 3b 00 cmpb $0x0,(%rbx,%r15,1)
10: 74 08 je 0x1a
12: 4c 89 ef mov %r13,%rdi
15: e8 bd ec 61 00 call 0x61ecd7
1a: 49 f7 45 00 01 00 00 testq $0x1,0x0(%r13)
21: 00
22: 0f 85 8b 00 00 00 jne 0xb3
28: f3 90 pause
* 2a: 4c 89 ef mov %r13,%rdi <-- trapping instruction
2d: be 08 00 00 00 mov $0x8,%esi
32: e8 30 ee 61 00 call 0x61ee67
37: 42 80 3c 3b 00 cmpb $0x0,(%rbx,%r15,1)
3c: 0f .byte 0xf
3d: 84 .byte 0x84
3e: 84 fe test %bh,%dh


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