Bug 635857
| Summary: | libvirt-0.8.4 fails to start VMs after upgrade | |||
|---|---|---|---|---|
| Product: | [Community] Virtualization Tools | Reporter: | Thomas <merlin.linux> | |
| Component: | libvirt | Assignee: | Eric Blake <eblake> | |
| Status: | CLOSED UPSTREAM | QA Contact: | ||
| Severity: | medium | Docs Contact: | ||
| Priority: | low | |||
| Version: | unspecified | CC: | berrange, crobinso, eblake, xen-maint | |
| Target Milestone: | --- | Keywords: | Reopened | |
| Target Release: | --- | |||
| Hardware: | x86_64 | |||
| OS: | Linux | |||
| Whiteboard: | ||||
| Fixed In Version: | Doc Type: | Bug Fix | ||
| Doc Text: | Story Points: | --- | ||
| Clone Of: | ||||
| : | 636347 (view as bug list) | Environment: | ||
| Last Closed: | 2010-09-22 15:10:07 UTC | Type: | --- | |
| 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: | 636347, 636349 | |||
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Description
Thomas
2010-09-20 22:06:50 UTC
I can confirm that it's definitively the kernel option. I only changed it, recompiled the kernel and after that libvirt worked again without the error messages. CONFIG_HOTPLUG_CPU: Symbol: HOTPLUG_CPU [=y] │ Prompt: Support for hot-pluggable CPUs │ Defined at arch/x86/Kconfig:1634 │ Depends on: SMP [=y] && HOTPLUG [=y] │ Location: │ -> Processor type and features This is probably related to this recent change:
commit d413e5d7659f07994a79290a56c904a9b136ee2d
Author: Eric Blake <eblake>
Date: Tue Aug 10 15:33:37 2010 -0600
nodeinfo: skip offline CPUs
I can't yet spot the problem though - it attempts to cope with fact that the directory may not exist at all, so disabling hotplug in your kernel ought not to have broken it. Perhaps Eric can spot the problem.
I agree with danpb's analysis that commit d413e5d7 is the culprit. I only tested that commit on a hot-plug enabled kernel. So the fact that disabling hot-plugging makes /sys/devices/system/cpu/cpu<n>/ directories disappear makes sense, but was something I never encountered during my testing.
My patch only allowed a missing directory for cpu0 (since x86_64 systems with hot-unplug cpu support still disallow hot-unplugging cpu0). The fix is to allow a missing directory for all possible cpus:
diff --git i/src/nodeinfo.c w/src/nodeinfo.c
index 65eeb24..3dac9f3 100644
--- i/src/nodeinfo.c
+++ w/src/nodeinfo.c
@@ -65,7 +65,8 @@ int linuxNodeInfoCPUPopulate(FILE *cpuinfo,
/* Return the positive decimal contents of the given
* CPU_SYS_PATH/cpu%u/FILE, or -1 on error. If MISSING_OK and the
* file could not be found, return 1 instead of an error; this is
- * because some machines cannot hot-unplug cpu0. */
+ * because some machines cannot hot-unplug cpu0, or because
+ * hot-unplugging is disabled. */
static int
get_cpu_value(unsigned int cpu, const char *file, bool missing_ok)
{
@@ -113,7 +114,7 @@ cleanup:
static int
cpu_online(unsigned int cpu)
{
- return get_cpu_value(cpu, "online", cpu == 0);
+ return get_cpu_value(cpu, "online", true);
}
static unsigned long count_thread_siblings(unsigned int cpu)
|