Re: [REGRESSION][BISECTED] usb: hub: total system freeze after running adb

[Michal Pecio <michal.pecio@gmail.com>]

On Mon, 17 Nov 2025 12:18:54 -0800, Forest wrote:
> #regzbot introduced 8f5b7e2bec1c
> 
> Running adb (android debug bridge) commands causes the entire system to
> freeze some time later.
> 
> The freeze usually occurs within two hours of running adb, but not always.
> Stopping adb's persistent background process with `adb kill-server` seems to
> avoid the freeze. (However, this is not always possible, since the system
> sometimes freezes just a few seconds after adb is launched.)
> 
> It occurs even when no android devices are connected to the system.

Hi,

If this is caused by running some demon without much hardware connected
(besides hubs, I guess), I wonder if it might be useful to run strace on
that thing to see what it is even doing to trigger this crash.

> - No messages are written to dmesg or syslog.
> - Virtual console switching no longer works.
> - SysRq key commands no longer work, as far as I can tell.
> - Whatever was on the display remains intact.
> - Any already-playing audio enters a short loop, as though the
>   motherboard's sound device is playing from a ring buffer that
>   no longer gets updated.

How can you know nothing is logged if the machine becomes unresponsive?
For such occasions I keep a PCIe card with a serial port to get logs.
Maybe xHCI debug capability could work too (?), but I've never tried.

Regards,
Michal