Bug 160600

Summary: Accessing automounted directories can cause a process to hang forever
Product: Red Hat Enterprise Linux 3 Reporter: Jeff Moyer <jmoyer>
Component: kernelAssignee: Jeff Moyer <jmoyer>
Status: CLOSED ERRATA QA Contact: Brock Organ <borgan>
Severity: medium Docs Contact:
Priority: medium    
Version: 3.0CC: aspanke, cfeist, petrides, tao
Target Milestone: ---   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: RHSA-2006-0437 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2006-07-20 13:24:35 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:
Bug Depends On:    
Bug Blocks: 181405    
Attachments:
Description Flags
Fix a race in the tail end of an expire event, causing a process to hang forever. none

Description Jeff Moyer 2005-06-15 23:54:25 UTC 
Description of problem:
Automount can cause a program to hang when accessing a directory that is being
expired.

Version-Release number of selected component (if applicable):
autofs-4.1.3-130
kernel-2.4.21-32

How reproducible:
No reproducer available.

Steps to Reproduce:
1.
2.
3.
  
Actual results:
If the race is triggered, the process performing the lookup will hang
indefinitely.  You will be able to interrupt it, though.

Expected results:


Additional info:
This issue was reported upstream, and is resolved with the attached patch.  The
race is pretty clear, once you understand the code path, and the fix looks
straight forward and correct.
Comment 1 Jeff Moyer 2005-06-15 23:54:25 UTC 
Created attachment 115514 [details]
Fix a race in the tail end of an expire event, causing a process to hang forever.
Comment 2 Jeff Moyer 2005-06-15 23:55:05 UTC 
Posting patch to internal mailing list for review.
Comment 3 Ernie Petrides 2006-02-16 00:49:42 UTC 
A fix for this problem has just been committed to the RHEL3 U8
patch pool this evening (in kernel version 2.4.21-40.1.EL).
Comment 4 Ernie Petrides 2006-04-28 21:42:31 UTC 
Adding a couple dozen bugs to CanFix list so I can complete the stupid advisory.
Comment 6 Jeff Moyer 2006-05-03 17:56:51 UTC 
*** Bug 180343 has been marked as a duplicate of this bug. ***
Comment 7 Joshua Giles 2006-05-31 17:48:30 UTC 
I do see "no reproducer available," however can you provide steps you used
to make it reproduce in your environment?
Comment 8 Jeff Moyer 2006-06-01 00:27:28 UTC 
You could setup a simple map with a low timeout (say 5 seconds).  Then, have a
script constantly access the mount point at 5 second intervals.  Ensure that
mounts and unmounts are occurring.  If not, up the script interval to 6 seconds.
 The unmount/mount pair must occur quite close to each other.
Comment 10 Red Hat Bugzilla 2006-07-20 13:24:36 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 the 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/RHSA-2006-0437.html