Pagefault and Kernel Panic with flaky USB setup

[DrDebug42]

Hi,

for an experimental Haiku installation (R1/beta4) I used an older machine with a somewhat special USB setup for input (KVM, USB hub, ...). In a Linux installation on the same machine I have seen kernel error messages as well but on Haiku I frequently get Kernel Panics on the machine. The KDL does not react to any input, I presume this is because the panic seems to be related to USB. I have taken a picture of the KDL crash stack and will attach it to this ticket.

I tried to have a look at the source code and relate it to the crash stack and I think I found and attempted to fix the issue in the following change (admittedly I did not demangle the functions calls from the stack):

​https://review.haiku-os.org/c/haiku/+/7821

I tried several boots with a recent nightly build (anyboot on USB stick) including my fix without any issue. Trying the same nightly build without the fix resulted in a panic on the first try.

I will try to get at the syslog of the machine and include it here as well.

Best regards and many thanks

Timm

[DrDebug42]

Screenshot of the KDL panic and callstack