Pkg xen devel - Sep 2021 - Bug#939186: irt: Bug #939186 and 4.11/4.14

Package: xen-hypervisor-4.8-amd64
Version: 4.8.5+shim4.10.2+xsa282-1+deb9u11

Trying to create a HVM domain with memory != maxmem reliably crashes
Debian's build of Xen 4.8.  This may be a nonsensical configuration, but
it still shouldn't cause everything, including the hypervisor to crash.

I recall running into this with 4.4 as well.


-- 
(\___(\___(\______          --=> 8-) EHM <=--          ______/)___/)___/)
 \BS (    |         ehem+sigmsg at m5p.com  PGP 87145445         |    )   /
  \_CS\   |  _____  -O #include <stddisclaimer.h> O-   _____  |   /  _/
8A19\___\_|_/58D2 7E3D DDF4 7BA6 <-PGP-> 41D1 B375 37D0 8714\_|_/___/5445

Control: found 939186 4.11.4+107-gef32c7afa2-1

Certainly reproduced with 4.11.  Most recently I tried 4.14 and it
*didn't* occur.

Problem is I've got two guesses:

First, system had most VMs shutdown for some experimentation.  Could be
having >50% of memory allocated is needed for this to occur.

Second, could be the issue got fixed sometime before 4.14.


I *really* hope it is the second, but #939186 should remain open for a
while so that experimentation can occur.


-- 
(\___(\___(\______          --=> 8-) EHM <=--          ______/)___/)___/)
 \BS (    |         ehem+sigmsg at m5p.com  PGP 87145445         |    )   /
  \_CS\   |  _____  -O #include <stddisclaimer.h> O-   _____  |   /  _/
8A19\___\_|_/58D2 7E3D DDF4 7BA6 <-PGP-> 41D1 B375 37D0 8714\_|_/___/5445

Processing control commands:
> found 939186 4.11.4+107-gef32c7afa2-1
Bug #939186 [src:xen] HVM + Balloon crashes Xen hypervisor
Marked as found in versions xen/4.11.4+107-gef32c7afa2-1.

-- 
939186: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=939186
Debian Bug Tracking System
Contact owner at bugs.debian.org with problems

found 939186 4.14.2+25-gb6a8c4f72d-2
found 939186 4.14.3-1
tags 939186 upstream
quit

Upon a bit more experimentation, seems my minimal example had become too
minimal.  Bring in the less minimal example and things explode again.

Finally setup an appropriate downtime window and it reproduced.  After
some fighting to get Xen's console operational, detail on the panic was
recorded.

My wild guess from the output is some combination of enabling
"nestedhvm"
and this being an AMD processor machine.


-- 
(\___(\___(\______          --=> 8-) EHM <=--          ______/)___/)___/)
 \BS (    |         ehem+sigmsg at m5p.com  PGP 87145445         |    )   /
  \_CS\   |  _____  -O #include <stddisclaimer.h> O-   _____  |   /  _/
8A19\___\_|_/58D2 7E3D DDF4 7BA6 <-PGP-> 41D1 B375 37D0 8714\_|_/___/5445

Your message dated Wed, 27 Oct 2021 15:58:16 -0700
with message-id <YXnZiKN5tha714UP at mattapan.m5p.com>
and subject line Bug#939186: Poor documentation indeed
has caused the Debian Bug report #939186,
regarding HVM + Balloon crashes Xen hypervisor
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

(NB: If you are a system administrator and have no idea what this
message is talking about, this may indicate a serious mail system
misconfiguration somewhere. Please contact owner at bugs.debian.org
immediately.)


-- 
939186: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=939186
Debian Bug Tracking System
Contact owner at bugs.debian.org with problems
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