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Bug 324881

Summary: first mount can hang during parallel mounts
Product: [Retired] Red Hat Cluster Suite Reporter: David Teigland <teigland>
Component: GFS-kernelAssignee: David Teigland <teigland>
Status: CLOSED CURRENTRELEASE QA Contact: Cluster QE <mspqa-list>
Severity: low Docs Contact:
Priority: low    
Version: 4CC: akarlsso, cfeist, cmarthal, djuran, swhiteho
Target Milestone: ---   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
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Last Closed: 2009-03-12 19:54:47 UTC Type: ---
Regression: --- Mount Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Description Flags
possible patch none

Description David Teigland 2007-10-09 13:47:17 UTC 
Description of problem:

This was found while trying to reproduce bz 299061. Running the test in
comment 17 of that bz seems to reproduce this bug quite easily; at least
in my xen cluster which is not smp, this bug may be harder to hit on
smp machines.

It's easy to tell if you've hit this bug, because a message like this will
always appear in /var/log/messages:

SM: 02000378 ignoring service callback id=2000144 event=1324

If you look at /proc/cluster/lock_dlm/debug on this node at this point,
you'll see something like this at the end, which shows what the problem
is:

others_may_mount start_done 1322 b

The event_id that others_may_mount uses when calling kcl_start_done()
is incorrect; it's using 1322 when it should be 1324.

I believe the fix is for others_may_mount() to read the event_id
after taking the umount_lock semaphore which serializes
others_may_mount() with a start callback from the lock_dlm thread.
In this case, I believe the start callback is changing the event_id
after others_may_mount reads it, and before othres_may_mount gets
the umount_lock semaphore.

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


How reproducible:


Steps to Reproduce:
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Actual results:


Expected results:


Additional info:
Comment 1 David Teigland 2007-10-10 14:08:40 UTC 
This has not been reproducable on smp machines so far.
Comment 2 David Teigland 2007-10-15 13:39:07 UTC 
Created attachment 227681 [details]
possible patch

This patch seems to fix the problem.
Comment 3 David Teigland 2008-01-14 15:36:03 UTC 
fix checked into RHEL4 branch

Checking in mount.c;
/cvs/cluster/cluster/gfs-kernel/src/dlm/Attic/mount.c,v  <--  mount.c
new revision: 1.11.2.4; previous revision: 1.11.2.3
Comment 4 Steve Whitehouse 2009-01-20 15:19:41 UTC 
This seemed to be missing flags.
Comment 5 Chris Feist 2009-03-12 19:54:47 UTC 
This was fxied way back in January of 2008, it's already in 4.7.