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IDProjectCategoryView StatusLast Update
0006893Xen4[CentOS-6] -OTHERpublic2014-01-10 12:59
ReporterJohnnyHughes 
PrioritynormalSeverityminorReproducibilityalways
StatusnewResolutionopen 
Product Version[CentOS-6] 6.5 
Target Version[CentOS-6] 6.5Fixed in Version 
Summary0006893: xen_balloon errors in syslog
DescriptionThis mailing list thread discusses the issue:

http://lists.centos.org/pipermail/centos-virt/2014-January/003579.html

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System RAM resource [mem 0xc8000000-0xcfffffff] cannot be added
xen_balloon: reserve_additional_memory: add_memory() failed: -17
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-Notes

~0018820

JohnnyHughes (administrator)

This from David Vrabel on the mail list:

Drivers (e.g., blkback) use ballooned pages for use for foreign
mappings. Depending on dom0_mem options there may be no ballooned
memory available at boot and dom0's balloon is increased by allocating
pages. This decreases current_kb.

The balloon driver then tries to decrease the balloon to match the
target but it can only do this by hotplugging new memory. A bug in the
balloon driver means the location of this memory overlaps with an
address range that is already in use and the hotplug will fail.

As a workaround you can boot dom0 with a suitable amount of
pre-ballooned memory with:

   dom0_mem=3G,max:4G

You may need to experiment with the max: value.

~0018821

JohnnyHughes (administrator)

I would suggest that approx. 16 MB per VM is a reasonable amount of
pre-ballooned memory.

e.g., dom0_mem=3G,max:4G would allow for approx. 64 VMs.
+Notes

-Issue History
Date Modified Username Field Change
2014-01-10 12:57 JohnnyHughes New Issue
2014-01-10 12:58 JohnnyHughes Note Added: 0018820
2014-01-10 12:59 JohnnyHughes Note Added: 0018821
+Issue History