Bug 873134
Summary: | setting current memory equal to max will end with domain start as current > max | ||
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Product: | Red Hat Enterprise Linux 6 | Reporter: | Wayne Sun <gsun> |
Component: | libvirt | Assignee: | Laine Stump <laine> |
Status: | CLOSED ERRATA | QA Contact: | Virtualization Bugs <virt-bugs> |
Severity: | medium | Docs Contact: | |
Priority: | medium | ||
Version: | 6.4 | CC: | acathrow, dyasny, dyuan, honzhang, mzhan, rwu, zhpeng |
Target Milestone: | rc | ||
Target Release: | --- | ||
Hardware: | x86_64 | ||
OS: | Linux | ||
Whiteboard: | |||
Fixed In Version: | libvirt-0.10.2-9.el6 | Doc Type: | Bug Fix |
Doc Text: | Story Points: | --- | |
Clone Of: | Environment: | ||
Last Closed: | 2013-02-21 07:11:30 UTC | Type: | Bug |
Regression: | --- | Mount Type: | --- |
Documentation: | --- | CRM: | |
Verified Versions: | Category: | --- | |
oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
Cloudforms Team: | --- | Target Upstream Version: | |
Embargoed: | |||
Bug Depends On: | |||
Bug Blocks: | 881827 |
Description
Wayne Sun
2012-11-05 08:42:08 UTC
Fix has been pushed upstream: commit 89204fca7f193c7cf48f941bf2917c1a0e71096c Author: Laine Stump <laine> Date: Fri Nov 16 10:53:04 2012 -0500 qemu: allow larger discrepency between memory & currentMemory in domain xml This resolves: https://bugzilla.redhat.com/show_bug.cgi?id=873134 The reported problem is that an attempt to restore a saved domain that was configured with <currentMemory> and <memory> set to some (same for both) number that's not a multiple of 4096KiB results in an error like this: error: Failed to start domain libvirt_test_api error: XML error: current memory '4001792k' exceeds maximum '4000768k' (in this case, currentMemory was set to 4000000KiB). The reason for this failure is: 1) a saved image contains the "live xml" of the domain at the time of the save. 2) the live xml of a running domain gets its currentMemory (a.k.a. cur_balloon) directly from the qemu monitor rather than from the configuration of the domain. 3) the value reported by qemu is (sometimes) not exactly what was originally given to qemu when the domain was started, but is rounded up to [some indeterminate granularity] - in some versions of qemu that granularity is apparently 1MiB, and in others it is 4MiB. 4) When the XML is parsed to setup the state of the restored domain, the XML parser for <currentMemory> compares it to <memory> (which is the maximum allowed memory size for the domain) and if <currentMemory> is greater than the next 1024KiB boundary above <memory>, it spits out an error and fails. For example (from the BZ) if you start qemu on RHEL6 with both <currentMemory> and <memory> of 4000000 (this number is in KiB), libvirt's dominfo or dumpxml will report "4001792" back (rounded up to next 4MiB) for 10-20 seconds after the start, then revert to reporting "4000000". On Fedora 16 (which uses qemu-1.0), it will instead report "4000768" (rounded up to next 1MiB). On Fedora 17 (qemu-1.2), it seems to always report "4000000". ("4000000" is of course okay, and "4000768" is also okay since that's the next 1024KiB boundary above "4000000" and the parser was already allowing for that. But "4001792 is *not* okay and produces the error message.) This patch solves the problem by changing the allowed "fudge factor" when parsing from 1024KiB to 4096KiB to match the maximum up-rounding that could be done in qemu. (I had earlier thought to fix this by up-rounding <memory> in the dumpxml that's put into the saved image, but that wouldn't have fixed the case where the save image was produced by an "unfixed" libvirtd.) Verify it as follows.The result is expected. Move its status to VERIFIED. # rpm -q libvirt qemu-kvm libvirt-0.10.2-9.el6.x86_64 qemu-kvm-0.12.1.2-2.334.el6.x86_64 # virsh edit rhel6 ..... <memory unit='KiB'>2000000</memory> <currentMemory unit='KiB'>2000000</currentMemory> ..... Domain rhel6 XML configuration edited. # virsh start rhel6 Domain rhel6 started # virsh managedsave rhel6 Domain rhel6 state saved by libvirt # virsh start rhel6 Domain rhel6 started # virsh dumpxml rhel6 <domain type='kvm' id='36'> ..... <memory unit='KiB'>2000896</memory> <currentMemory unit='KiB'>2000000</currentMemory> ..... </domain> Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. http://rhn.redhat.com/errata/RHSA-2013-0276.html |