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

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Message-ID: <20251118105929.330f0042.michal.pecio@gmail.com>
Date: Tue, 18 Nov 2025 10:59:29 +0100
From: Michal Pecio <michal.pecio@...il.com>
To: Forest <forestix@...a.casa>
Cc: Mathias Nyman <mathias.nyman@...ux.intel.com>, Greg Kroah-Hartman
 <gregkh@...uxfoundation.org>, Alan Stern <stern@...land.harvard.edu>,
 Heikki Krogerus <heikki.krogerus@...ux.intel.com>, Stefan Eichenberger
 <stefan.eichenberger@...adex.com>, Pawel Laszczak <pawell@...ence.com>,
 linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
 regressions@...ts.linux.dev
Subject: Re: [REGRESSION][BISECTED] usb: hub: total system freeze after
 running adb

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