Bug 681492

Summary: virsh start guest got "Out of space while reading console log output" errors
Product: Red Hat Enterprise Linux 6 Reporter: Vivian Bian <vbian>
Component: libvirtAssignee: Jiri Denemark <jdenemar>
Status: CLOSED ERRATA QA Contact: Virtualization Bugs <virt-bugs>
Severity: medium Docs Contact:
Priority: high    
Version: 6.1CC: ajia, berrange, dallan, eblake, jyang, mzhan, xen-maint, yoyzhang
Target Milestone: rc   
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: libvirt-0.8.7-16.el6 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
: 710404 (view as bug list) Environment:
Last Closed: 2011-05-19 13:28:29 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On:    
Bug Blocks: 710404    
Attachments:
Description Flags
/var/log/libvirt/qemu/guest.log none

Description Vivian Bian 2011-03-02 11:21:59 UTC 
Description of problem:
with the same guest , and nothing modified for the guest would got the following error output occasionally
 
# virsh start RHEL5.6-i386
error: Failed to start domain RHEL5.6-i386
error: internal error Out of space while reading console log output: 11:13:54.230: 4311: info : libvirt version: 0.8.7, package: 8.el6 (Red Hat, Inc. <http://bugzilla.redhat.com/bugzilla>, 2011-02-24-17:53:33, x86-006.build.bos.redhat.com)
11:13:54.230: 4311: debug : virCgroupNew:555 : New group /libvirt/qemu/RHEL5.6-i386
11:13:54.230: 4311: debug : virCgroupDetect:245 : Detected mount/mapping 0:cpu at /cgroup/cpu in 
11:13:54.230: 4311: debug : virCgroupDetect:245 : Detected mount/mapping 1:cpuacct at /cgroup/cpuacct in 
11:13:54.230: 4311: debug : virCgroupDetect:245 : Detected mount/mapping 2:cpuset at /cgroup/cpuset in 
11:13:54.230: 4311: debug : virCgroupDetect:245 : Detected mount/mapping 3:memory at /cgroup/memory in 
11:13:54.230: 4311: debug : virCgroupDetect:245 : Detected mount/mapping 4:devices at /cgroup/devices in 
11:13:54.230: 4311: debug : virCgroupDetect:245 : Detected mount/mapping 5:freezer at /cgroup/freezer in 
11:13:54.230: 4311: debug : virCgroupDetect:245 : Detected mount/mapping 6:blkio at /cgroup/blki


Version-Release number of selected component (if applicable):
libvirt-0.8.7-8.el6.x86_64



Steps to Reproduce:
1. virsh start guest 
2.
3.
  
Actual results:


Expected results:
no such error output prevent from starting the guest 

Additional info:
Comment 2 Jiri Denemark 2011-03-02 12:34:54 UTC 
The problem is a stack-allocated buffer in qemudWaitForMonitor:

char buf[4096] = ""; /* Plenty of space to get startup greeting */

Apparently, it's much less than plenty, it's even not enough since it also needs to accommodate all the debug messages printed by libvirt when it prepares for starting up qemu binary.
Comment 3 Daniel Berrangé 2011-03-02 12:41:05 UTC 
It was never expected to have to store debug messages. In addition those debug messages aren't really something we want to pass onto the user in the error message. If QEMU fails, we need to figure out how to skip over the libvirt debug messages & just provide the QEMU error message. If we manage that, then 4k should still be sufficient for the QEMU error message.
Comment 4 Vivian Bian 2011-03-09 08:07:06 UTC 
Created attachment 483123 [details]
/var/log/libvirt/qemu/guest.log
Comment 6 Jiri Denemark 2011-04-01 07:39:30 UTC 
Patch sent for review: http://post-office.corp.redhat.com/archives/rhvirt-patches/2011-April/msg00001.html
Comment 9 Vivian Bian 2011-04-07 07:03:14 UTC 
retested with 
libvirt-0.8.7-16.el6.x86_64
qemu-kvm-0.12.1.2-2.153.el6.x86_64
kernel-2.6.32-128.el6.x86_64

1. virsh start guest for about 30 times , didn't meet "Out of space" error . 

So set bug status to VERIFIED
Comment 12 errata-xmlrpc 2011-05-19 13:28:29 UTC 
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHBA-2011-0596.html