linux-kernel - [syzbot] [bridge?] INFO: task hung in br_ioctl

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Message-ID: <692dcb93.a70a0220.2ea503.00b6.GAE@google.com>
Date: Mon, 01 Dec 2025 09:08:35 -0800
From: syzbot <syzbot+6bdeba54c73aa6a6219d@...kaller.appspotmail.com>
To: bridge@...ts.linux.dev, davem@...emloft.net, edumazet@...gle.com, 
	horms@...nel.org, idosch@...dia.com, kuba@...nel.org, 
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org, pabeni@...hat.com, 
	razor@...ckwall.org, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [bridge?] INFO: task hung in br_ioctl_stub (2)

Hello,

syzbot found the following issue on:

HEAD commit:    765e56e41a5a Merge tag 'v6.18rc7-SMB-client-fix' of git://..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=159ace12580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a1db0fea040c2a9f
dashboard link: https://syzkaller.appspot.com/bug?extid=6bdeba54c73aa6a6219d
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12ddee12580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-765e56e4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fd649009c819/vmlinux-765e56e4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/bf3e0d5c78c2/bzImage-765e56e4.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6bdeba54c73aa6a6219d@...kaller.appspotmail.com

INFO: task syz.0.27:5720 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.27        state:D stack:28904 pid:5720  tgid:5719  ppid:5469   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929
 __schedule_loop kernel/sched/core.c:7011 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7026
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7083
 __mutex_lock_common kernel/locking/mutex.c:676 [inline]
 __mutex_lock+0x7e6/0x1350 kernel/locking/mutex.c:760
 br_ioctl_stub+0x199/0xc80 net/bridge/br_ioctl.c:418
 br_ioctl_call net/socket.c:1227 [inline]
 sock_ioctl+0x4d8/0x790 net/socket.c:1329
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f91bf78f7c9
RSP: 002b:00007f91c0675038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f91bf9e5fa0 RCX: 00007f91bf78f7c9
RDX: 0000200000000000 RSI: 00000000000089a2 RDI: 0000000000000003
RBP: 00007f91bf813f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f91bf9e6038 R14: 00007f91bf9e5fa0 R15: 00007ffd440d2c68
 </TASK>
INFO: task kworker/u4:11:5722 blocked for more than 150 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:11   state:D stack:28872 pid:5722  tgid:5722  ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: events_unbound linkwatch_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929
 __schedule_loop kernel/sched/core.c:7011 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7026
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7083
 __mutex_lock_common kernel/locking/mutex.c:676 [inline]
 __mutex_lock+0x7e6/0x1350 kernel/locking/mutex.c:760


---
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 syzkaller@...glegroups.com.

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If the report is already addressed, let syzbot know by replying with:
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