Ubuntu
xen package

xm migrate --live panics hypervisor

Bug #1515145 reported by Volker
16
This bug affects 2 people
Affects Status Importance Assigned to Milestone
xen (Ubuntu)
Confirmed
Undecided
Unassigned

Bug Description

I have to HP Proliant D380 Gen8 Servers with a shared iSCSI storage in a xen cluster configuration. They run 12.04 amd64 and are fully patched and freshly rebooted.

When i call
 /usr/sbin/xm migrate --live <some-domain-id> <ip-over-other-host>
on one server this "sending" system reboots instantly and the VM only appears in an undefined state on the "receiving" host.

After redirecting the console output of the hypervisor to com1 i was able to retrieve this error message:

(XEN) [2015-11-11 07:50:05] traps.c:3073: GPF (0000): ffff82c48017fa31 -> ffff82c4802070d8
(XEN) [2015-11-11 07:50:15]
(XEN) [2015-11-11 07:50:15] ****************************************
(XEN) [2015-11-11 07:50:15] Panic on CPU 10:
(XEN) [2015-11-11 07:50:15] mm lock held by sh_page_fault__guest_4
(XEN) [2015-11-11 07:50:15] ****************************************
(XEN) [2015-11-11 07:50:15]
(XEN) [2015-11-11 07:50:15] Manual reset required ('noreboot' specified)

After replacing "/boot/xen-4.1-amd64.gz" with the file from debian wheezy package "xen-hypervisor-4.1-amd64_4.1.4-3+deb7u9_amd64.deb" the problem is gone.

Tags: patch
Revision history for this message
Volker (volker-reiss) wrote :
Revision history for this message
Volker (volker-reiss) wrote :
Revision history for this message
Volker (volker-reiss) wrote :

uname -srvm
Linux 3.2.0-94-generic #134-Ubuntu SMP Fri Nov 6 18:16:45 UTC 2015 x86_64

Working hypervisor versions:

(XEN) Xen version 4.1.6.1 (Ubuntu 4.1.6.1-0ubuntu0.12.04.5) (<email address hidden>) (gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5) ) Wed Mar 11 15:00:28 UTC 2015

(XEN) Xen version 4.1.4 (Debian 4.1.4-3+deb7u9) (<email address hidden>) (gcc version 4.7.2 (Debian 4.7.2-5) ) Sat Oct 31 06:17:33 UTC 2015

Non working hypervisor version:

(XEN) Xen version 4.1.6.1 (Ubuntu 4.1.6.1-0ubuntu0.12.04.6) (<email address hidden>) (gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5) ) Wed Sep 2 18:06:32 UTC 2015

Revision history for this message
Launchpad Janitor (janitor) wrote :

Status changed to 'Confirmed' because the bug affects multiple users.

Changed in xen (Ubuntu):
status: New → Confirmed
Revision history for this message
Philipp Hahn (pmhahn) wrote :

Reverting the following patches makes the crash go away (4.1.6.1-0ubuntu0.12.04.8):
* xsa97-hap-4.1-prereq.patch
* xsa97-hap-4.2-prereq.patch
* xsa97-hap-4.2.patch

Revision history for this message
Philipp Hahn (pmhahn) wrote :

debian/patches/xsa97-hap-4.1-prereq.patch is the combination of
 * commit 301493fb027648db6808b66d1ccf849f524b8422
   x86/mm: dedup the various copies of the shadow lock functions
 * commit eca988de7381e5efe58792dc166611e4523d33b3
   x86/mm: merge the shadow, hap and log-dirty locks into a single paging lock.

but it's missing
 * commit 5bf494a7bf3674f32ebaab1b70b76e5f174812a3
   x86/mm: Make MM locks recursive.

which leads to a recursive locking call to crash the hypervisor.

With the patch applied "xm migrate -c -l $dom $host" works again.

Revision history for this message
Ubuntu Foundations Team Bug Bot (crichton) wrote :

The attachment "x86/mm: Make MM locks recursive." seems to be a patch. If it isn't, please remove the "patch" flag from the attachment, remove the "patch" tag, and if you are a member of the ~ubuntu-reviewers, unsubscribe the team.

[This is an automated message performed by a Launchpad user owned by ~brian-murray, for any issues please contact him.]

tags: added: patch
Revision history for this message
Philipp Hahn (pmhahn) wrote :

The first patch does not work!

The backport was quiet complicates as that patch is in the middle of
4) eca988d x86/mm: merge the shadow, hap and log-dirty locks into a single paging lock.
3) 5bf494a x86/mm: Make MM locks recursive.
2) 301493f x86/mm: dedup the various copies of the shadow lock functions
1) 3b0bcb8 x86/mm/p2m: Move p2m code in HVMOP_[gs]et_mem_access into p2m.c

2) and 4) are already in debian/patches/xsa97-hap-4.1-prereq.patch, so the patch also contains the parts from eca988d which where skipped as 5bf494a was not back-ported.

This patch also requires a back-port of 3b0bcb890955e1c3e2fde10a026c5d85481e6fb8 (1) as compilation failes otherwise - I'll attach that next - as an alternative it could be enough to '#include "../mm-locks.h"' instead, but I didn't test that.

Revision history for this message
Philipp Hahn (pmhahn) wrote :

Backport 3b0bcb8 x86/mm/p2m: Move p2m code in HVMOP_[gs]et_mem_access into p2m.c

Revision history for this message
Philipp Hahn (pmhahn) wrote :

Backport 3b0bcb8 x86/mm/p2m: Move p2m code in HVMOP_[gs]et_mem_access into p2m.c
needs f488040222f34df97deb2470f14cef7fb9599810 to fix the build on i386.

f488040 Fix 32-bit build after p2m series
3b0bcb8 x86/mm/p2m: Move p2m code in HVMOP_[gs]et_mem_access into p2m.c

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