Re: [Xen-devel] [PATCH] xend: do not polling vcpus info if guest state is not RUNNING or PAUSED

[Joe Jin <joe.jin@xxxxxxxxxx>]

On 11/19/13 16:03, Roger Pau Monné wrote:
> On 19/11/13 07:13, Joe Jin wrote:
>> When created new guest on NUMA server, xend tried to get the best node by
>> calculated all vcpus info, the race is if other geust is rebooting, the
>> guest in the list when entered find_relaxed_node(), but when call
>> getVCPUInfo() the guest be terminated, then getVCPUInfo() will fail with
>> below error:
>>
>> [2013-09-04 20:01:26 6254] ERROR (XendDomainInfo:496) VM start failed
>> Traceback (most recent call last):
>>   File "/usr/lib64/python2.4/site-packages/xen/xend/XendDomainInfo.py", line 
>> 482, in start
>>     XendTask.log_progress(31, 60, self._initDomain)
>>   File "/usr/lib64/python2.4/site-packages/xen/xend/XendTask.py", line 209, 
>> in log_progress
>>     retval = func(*args, **kwds)
>>   File "/usr/lib64/python2.4/site-packages/xen/xend/XendDomainInfo.py", line 
>> 2918, in _initDomain
>>     node = self._setCPUAffinity()
>>   File "/usr/lib64/python2.4/site-packages/xen/xend/XendDomainInfo.py", line 
>> 2835, in _setCPUAffinity
>>     best_node = find_relaxed_node(candidate_node_list)[0]
>>   File "/usr/lib64/python2.4/site-packages/xen/xend/XendDomainInfo.py", line 
>> 2803, in find_relaxed_node
>>     cpuinfo = dom.getVCPUInfo()
>>   File "/usr/lib64/python2.4/site-packages/xen/xend/XendDomainInfo.py", line 
>> 1600, in getVCPUInfo
>>     raise XendError(str(exn))
>> XendError: (3, 'No such process')
>>
>> This patch will let find_relaxed_node() only polling the RUNNING or PAUSED
>> guest vpus info to avoid the race.
>>
>> Signed-off-by: Joe Jin <joe.jin@xxxxxxxxxx>
>> ---
>>  tools/python/xen/xend/XendDomainInfo.py |    2 ++
>>  1 files changed, 2 insertions(+), 0 deletions(-)
>>
>> diff --git a/tools/python/xen/xend/XendDomainInfo.py 
>> b/tools/python/xen/xend/XendDomainInfo.py
>> index e9d3e7e..66e4b9f 100644
>> --- a/tools/python/xen/xend/XendDomainInfo.py
>> +++ b/tools/python/xen/xend/XendDomainInfo.py
>> @@ -2734,6 +2734,8 @@ class XendDomainInfo:
>>                  from xen.xend import XendDomain
>>                  doms = XendDomain.instance().list('all')
>>                  for dom in filter (lambda d: d.domid != self.domid, doms):
>> +                    if dom._stateGet() not in 
>> (DOM_STATE_RUNNING,DOM_STATE_PAUSED):
>> +                        continue
> 
> Isn't it possible that the domain has rebooted and is no longer there
> between this two calls?
> 
> IMHO it's very unlikely, but there's still a window where getVCPUInfo
> could fail.
> 

Yes your right, this patch just reduce the window. 
I created a new patch for this, please comment!

[PATCH] xend: getVCPUInfo should handle died domain

When created new guest on NUMA server, xend tried to get the best node by
calculated all vcpus info, the race is if other geust is rebooting, the
guest in the list when entered find_relaxed_node(), but when call
getVCPUInfo() the guest already be terminated, then getVCPUInfo() will
fail with  below error:

[2013-09-04 20:01:26 6254] ERROR (XendDomainInfo:496) VM start failed
Traceback (most recent call last):
  File "/usr/lib64/python2.4/site-packages/xen/xend/XendDomainInfo.py", line 
482, in start
    XendTask.log_progress(31, 60, self._initDomain)
  File "/usr/lib64/python2.4/site-packages/xen/xend/XendTask.py", line 209, in 
log_progress
    retval = func(*args, **kwds)
  File "/usr/lib64/python2.4/site-packages/xen/xend/XendDomainInfo.py", line 
2918, in _initDomain
    node = self._setCPUAffinity()
  File "/usr/lib64/python2.4/site-packages/xen/xend/XendDomainInfo.py", line 
2835, in _setCPUAffinity
    best_node = find_relaxed_node(candidate_node_list)[0]
  File "/usr/lib64/python2.4/site-packages/xen/xend/XendDomainInfo.py", line 
2803, in find_relaxed_node
    cpuinfo = dom.getVCPUInfo()
  File "/usr/lib64/python2.4/site-packages/xen/xend/XendDomainInfo.py", line 
1600, in getVCPUInfo
    raise XendError(str(exn))
XendError: (3, 'No such process')

This patch will handle the situation.

Signed-off-by: Joe Jin <joe.jin@xxxxxxxxxx>
---
 tools/python/xen/xend/XendDomainInfo.py |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/tools/python/xen/xend/XendDomainInfo.py 
b/tools/python/xen/xend/XendDomainInfo.py
index e9d3e7e..c6414ed 100644
--- a/tools/python/xen/xend/XendDomainInfo.py
+++ b/tools/python/xen/xend/XendDomainInfo.py
@@ -34,6 +34,7 @@ import os
 import stat
 import shutil
 import traceback
+import errno
 from types import StringTypes
 
 import xen.lowlevel.xc
@@ -1541,6 +1542,9 @@ class XendDomainInfo:
             return sxpr
 
         except RuntimeError, exn:
+            # Domain already died.
+            if exn.args[0] == errno.ESRCH:
+                return sxpr
             raise XendError(str(exn))
 
 
-- 
1.7.1



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel