CentOS 7.4 Fails To Boot As Xen PV Guest: Resurfaces (now Also) With CentOSplus Kernel 693.11.6.el7

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Dear all,

Maybe I’m the only one – so before filing it as a bug: it appears that the latest set of kernel patches in 3.10.0-693.11.6.el7 makes issue
0013763 “CentOS 7.4 kernel (3.10.0-693*) fails to boot as Xen PV guest”
re-surface *also* with the CentOS PLUS kernel. But maybe in a different way …

Thanks to the (great!) quick work on making the plus kernel available
(in #14330, thanks for that!) I was able to test the following combinations:

– 3.10.0-693.11.6.el7.CentOS.plus works fine on XenServer 7 HVM guests
– 3.10.0-693.11.1.el7.CentOS.plus works fine on XenServer 7 XenPV guests
– 3.10.0-693.11.6.el7.CentOS.plus crashes on boot for XS7 XenPV guests
immediately after the boot stage where the PS/2 drivers are loaded

Crashing does not depend on the amount of VM memory or #cores/sockets. Also, the tell-tale “mm/vmalloc.c” failure output is no longer present. The system ‘just’ crashes (with the kernel log lines as below) around the time of the i8042 controller probing.

Obviously the stock upstream 3.10.0-693.11.6.el7 crashes as well for XS7 XenPV guests, but that was to be expected as per 0013763. It crashes in the same way, around the time of the i8042 probes.

Can anyone (maybe bill_mcgonigle?) reproduce the issue?
Did the KPTI patches break the XenPV fixes in CentOS Plus per 13763?
Or is this a new XenPV issue?

Interestingly, the crash is now sudden and (even at loglevel=7)
without further information. The crash after the i8042/mousedev is (I think) unrelated to these devices, since the system crashes in the same way even with “i8042.debug i8042.nokbd i8042.noaux i8042.dumbkbd i8042.nomux i8042.noloop i8042.nopnp psmouse.proto

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