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Bug 251562

Summary: lowcomms_stop can't stop dlm_recvd
Product: Red Hat Enterprise Linux 4 Reporter: Dean Jansa <djansa>
Component: dlm-kernelAssignee: Christine Caulfield <ccaulfie>
Status: CLOSED DUPLICATE QA Contact: Cluster QE <mspqa-list>
Severity: medium Docs Contact:
Priority: medium    
Version: 4.5CC: ccaulfie, cluster-maint
Target Milestone: ---   
Target Release: ---   
Hardware: ia64   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2007-08-13 14:39:17 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:
Attachments:
Description Flags
link-13 sysreq-t
none
link-15 sysreq-t
none
link-16 sysreq-t none

Description Dean Jansa 2007-08-09 19:01:44 UTC 
Description of problem:

At the end of a revolver run our test suite attempted to stop the clvmd serice
on node causing other nodes clvmd to hang.  

link-13 was running 'service clvmd stop' which never completed.  All further
attempts to run any cluster lvm command hung.  I grabbed the stacks will attach
them to this bug.

Dave took a look at the stacks and said, "I think we'll need to have pjc look at
this -- it does look like a dlm problem.  clvmd trying to shut down dlm_recvd,
but dlm_recvd is blocking on a connection semaphore

Version-Release number of selected component (if applicable):

2.6.9-55.0.3.ELlargesmp
dlm-kernel-2.6.9-46.16.0.5

How reproducible:

Haven't tried.
Comment 1 Dean Jansa 2007-08-09 19:05:14 UTC 
Created attachment 161006 [details]
link-13 sysreq-t
Comment 2 Dean Jansa 2007-08-09 19:06:32 UTC 
Created attachment 161007 [details]
link-15 sysreq-t
Comment 3 Dean Jansa 2007-08-09 19:06:54 UTC 
Created attachment 161008 [details]
link-16 sysreq-t
Comment 4 Christine Caulfield 2007-08-10 10:35:01 UTC 
Oh good grief that "security bug" really opened a can of worms didn't it!

I suspect this is down to the 'othercon' structures being freed while the
receive thread is waiting to use it. I can't see any other way of getting into
that situation that described in the sysreq-t dumps (receive_from_sock waiting
for a semaphore that no-one seems to be holding). And the fact that all three
nodes are showing the same symptoms reinforces that it's not really some odd
race condition. I'm going to move the close connection logic into the
receive_from_sock() code so that it always happens on the same thread. The send
queue should be fine because we can manage that ourself but incoming stuff is a
little more unpredictable.
Comment 6 Christine Caulfield 2007-08-13 14:39:17 UTC 
Make this a duplicate of 238490 as it has all the patches and detail.

*** This bug has been marked as a duplicate of 238490 ***