On 12/9/21 09:27, syzbot wrote:
Hello, syzbot found the following issue on: HEAD commit: d598c3c46ea6 Merge 5.16-rc4 into usb-next git tree: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing console output: https://syzkaller.appspot.com/x/log.txt?x=14cf0e55b00000 kernel config: https://syzkaller.appspot.com/x/.config?x=c6df5f09a0b9c823 dashboard link: https://syzkaller.appspot.com/bug?extid=f39c1dad0b7db49ca4a8 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 Unfortunately, I don't have any reproducer for this issue yet. IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+f39c1dad0b7db49ca4a8@xxxxxxxxxxxxxxxxxxxxxxxxx INFO: task kworker/0:6:4133 blocked for more than 143 seconds. Not tainted 5.16.0-rc4-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/0:6 state:D stack:21848 pid: 4133 ppid: 2 flags:0x00004000 Workqueue: usb_hub_wq hub_event Call Trace: <TASK> context_switch kernel/sched/core.c:4972 [inline] __schedule+0x931/0x2320 kernel/sched/core.c:6253 schedule+0xd2/0x260 kernel/sched/core.c:6326 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6385 __mutex_lock_common kernel/locking/mutex.c:680 [inline] __mutex_lock+0xa32/0x12f0 kernel/locking/mutex.c:740 unregister_netdev+0xe/0x20 net/core/dev.c:11138 r871xu_dev_remove+0x24f/0x2c0 drivers/staging/rtl8712/usb_intf.c:599
Seems like syz-executor ddosed the kernel. unregister_netdev() tries to lock rtnl and there are 8 mentions of rtnl_mutex in "Showing all locks held in the system" section.
Looks false-positive to me With regards, Pavel Skripkin
