Red Hat Bugzilla – Bug 566930
Fedora 2.6.31 kernel save/restore/migration crashes on Xen PV guest
Last modified: 2010-12-03 17:34:46 EST
Description of problem:
Running Xen "xm save" and "xm restore" for a Fedora 12 Xen PV guest is unstable. For a single-vcpu guest it gives a BUG() after "xm restore" in the guest kernel, and for multi-vcpu guest "xm save" never finishes (the guest crashes).
Version-Release number of selected component (if applicable):
Fedora 12. All 2.6.31.* kernels, both 32bit and 64bit are affected. I reproduced this with all F12 kernel updates so far.
Steps to Reproduce:
1. Install Fedora 12 Xen PV guest. I used EL 5.4 dom0.
2. Run "xm save" and possibly "xm restore" in Xen dom0.
3. Guest gets BUG() in dmesg, or it crashes totally.
For a single-vcpu guests "xm save" works, but they get BUG() in their kernel log after "xm restore". Multi-vcpu guests crash immediately on "xm save". You have to "xm destroy" them.
save/restore/migration works OK without problems.
These save/restore/migration problems/bugs have been fixed in upstream kernel.org 2.6.32.X stable kernels. I compiled 126.96.36.199 upstream kernel.org kernel to the guest, and verified save/restore was stable then.
Discussion thread with more information and test results here:
The fix is to upgrade the F12 kernel to latest 2.6.32.x stable release, or if that's not planned, then apply the Xen related fixes that went to 2.6.32 and 2.6.32.x.
The thread link above is missing the test results for 2.6.32.x.
Those can be found from here:
*** Bug 566927 has been marked as a duplicate of this bug. ***
This bug has been fixed with the latest F12 2.6.32 kernel update.
I just tried save/restore with multiple F12 Xen PV guests running 188.8.131.52-70.fc12.x86_64, and save/restore is working OK without problems.
- F12 x86_64 Xen PV guest with 2 vcpus and 512 MB of RAM.
- F12 x86_64 Xen PV guest with 4 vcpus and 4096 MB of RAM.
I tried save/restore multiple times in a row. No problems found.
Yep, it seems to be working here too. (F12 x86 with 2 vcpus and 256MB of RAM)
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