Message-ID: <686ee4a0.050a0220.385921.0022.GAE@google.com>
Date: Wed, 09 Jul 2025 14:52:32 -0700
From: syzbot <syzbot+9196eb463ddf99a0be6e@...kaller.appspotmail.com>
To: cratiu@...dia.com, davem@...emloft.net, edumazet@...gle.com, 
	horms@...nel.org, kuba@...nel.org, kuniyu@...zon.com, 
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org, pabeni@...hat.com, 
	sdf@...ichev.me, syzkaller-bugs@...glegroups.com, vladimir.oltean@....com
Subject: [syzbot] [net?] WARNING: ./include/net/netdev_lock.h:LINE at
 __linkwatch_sync_dev, CPU: kworker/u8:NUM/NUM

Hello,

syzbot found the following issue on:

HEAD commit:    050f8ad7b58d Add linux-next specific files for 20250616
git tree:       linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=13ad8370580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d2efc7740224b93a
dashboard link: https://syzkaller.appspot.com/bug?extid=9196eb463ddf99a0be6e
compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=155c190c580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=109c95d4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/49faa18d2f53/disk-050f8ad7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7c6f9cd7fe5d/vmlinux-050f8ad7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/84a08d6403ee/bzImage-050f8ad7.xz

The issue was bisected to:

commit 04efcee6ef8d0f01eef495db047e7216d6e6e38f
Author: Stanislav Fomichev <sdf@...ichev.me>
Date:   Fri Apr 4 16:11:22 2025 +0000

    net: hold instance lock during NETDEV_CHANGE

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=16390dd4580000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=15390dd4580000
console output: https://syzkaller.appspot.com/x/log.txt?x=11390dd4580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9196eb463ddf99a0be6e@...kaller.appspotmail.com
Fixes: 04efcee6ef8d ("net: hold instance lock during NETDEV_CHANGE")

------------[ cut here ]------------
RTNL: assertion failed at ./include/net/netdev_lock.h (72)
WARNING: ./include/net/netdev_lock.h:72 at netdev_ops_assert_locked include/net/netdev_lock.h:72 [inline], CPU#0: kworker/u8:3/49
WARNING: ./include/net/netdev_lock.h:72 at __linkwatch_sync_dev+0x303/0x350 net/core/link_watch.c:279, CPU#0: kworker/u8:3/49
Modules linked in:
CPU: 0 UID: 0 PID: 49 Comm: kworker/u8:3 Not tainted 6.16.0-rc2-next-20250616-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: bond0 bond_mii_monitor
RIP: 0010:netdev_ops_assert_locked include/net/netdev_lock.h:72 [inline]
RIP: 0010:__linkwatch_sync_dev+0x303/0x350 net/core/link_watch.c:279
Code: 7c fe ff ff e8 5e 7f 66 f8 c6 05 ce 6b 31 06 01 90 48 c7 c7 20 2f 93 8c 48 c7 c6 7a 32 9d 8d ba 48 00 00 00 e8 9e 1d 2a f8 90 <0f> 0b 90 90 e9 4d fe ff ff 44 89 f1 80 e1 07 38 c1 0f 8c 22 fd ff
RSP: 0018:ffffc90000ba7670 EFLAGS: 00010246
RAX: a4c1d8d5a4094c00 RBX: ffff888032708000 RCX: ffff8880222a5a00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000002
RBP: 0000000000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff1bfaa14 R12: 1ffff110064e105d
R13: dffffc0000000000 R14: ffffffff8c1c95e8 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff888125c40000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000300 CR3: 000000007997c000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ethtool_op_get_link+0x15/0x70 net/ethtool/ioctl.c:63
 bond_check_dev_link+0x444/0x6c0 drivers/net/bonding/bond_main.c:863
 bond_miimon_inspect drivers/net/bonding/bond_main.c:2745 [inline]
 bond_mii_monitor+0x428/0x2e00 drivers/net/bonding/bond_main.c:2967
 process_one_work kernel/workqueue.c:3235 [inline]
 process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3318
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3399
 kthread+0x711/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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For information about bisection process see: https://goo.gl/tpsmEJ#bisection

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
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If you want to overwrite report's subsystems, reply with:
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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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