Note that this problem seems to have been introduced in RHEL 6.5.  RHEL 6.4 appears to use fuser instead of find /proc.

This logic has gone through several iterations for various reasons. We'll have to go back through the history why we ended up scanning the /proc/ directory to determine if 'lsof' usage is safe or not.

-- Vossel

We can't use lsof or fuser because of this issue, https://bugzilla.redhat.com/show_bug.cgi?id=1014298

Those tools use functions that can potentially block the file system resource-agents when nfs is in use somewhere on the system.  There is a lsof '-b' option that apparently tries to reduce the potential for blocking to occur, but after doing an strace I'm not convinced blocking will not occur.

As an alternative we can continue to use our custom shell logic and expand it to handle the use case where the process is using shared libraries that exist on the mount point being unmounted.

This is the logic I've introduced.

grep " ${mp}" /proc/[0-9]*/maps | awk -F/ '{print $3}' | uniq

The full patch can be found in this upstream pull request.

https://github.com/ClusterLabs/resource-agents/pull/422

-- Vossel

Created attachment 910804 [details]
unit test

I've attached a unit test. This test requires the bind-mount agent that was introduced in this bugzilla.

https://bugzilla.redhat.com/show_bug.cgi?id=1094789

Make sure you are using a build that has that new agent in it. This test is going to copy shared libraries over to a bind mount then execute commands that use those shared libraries.


#./bind-test_v3.sh
.
.
.
.
PASSED

*** Bug 1118358 has been marked as a duplicate of this bug. ***

I have verified with unittest from comment 7 that processes blocking  umounting of the system are correctly identified and killed with resource-agents-3.9.5-11.el6.x86_64

-----
# rpm -q resource-agents 
resource-agents-3.9.5-11.el6.x86_64

# ./bind-test_v3.sh 
umount: /root/testsrc: not mounted
umount: /root/target: not mounted
<debug>  Checking fs "testrsc", Level 
[bind-mount.sh] Checking fs "testrsc", Level 
<err>    default: /root/testsrc is not mounted on /root/target
[bind-mount.sh] default: /root/testsrc is not mounted on /root/target
<info>   /root/testsrc is not mounted
[bind-mount.sh] /root/testsrc is not mounted
<info>   mounting /root/testsrc on /root/target
[bind-mount.sh] mounting /root/testsrc on /root/target
<debug>  mount  -o bind /root/testsrc /root/target
[bind-mount.sh] mount  -o bind /root/testsrc /root/target
<debug>  Checking fs "testrsc", Level 
[bind-mount.sh] Checking fs "testrsc", Level 
<debug>  /root/testsrc already mounted
[bind-mount.sh] /root/testsrc already mounted
<info>   unmounting /root/target
[bind-mount.sh] unmounting /root/target
<info>   /root/testsrc is not mounted
[bind-mount.sh] /root/testsrc is not mounted
<debug>  Checking fs "testrsc", Level 
[bind-mount.sh] Checking fs "testrsc", Level 
<err>    default: /root/testsrc is not mounted on /root/target
[bind-mount.sh] default: /root/testsrc is not mounted on /root/target
<info>   mounting /root/testsrc on /root/target
[bind-mount.sh] mounting /root/testsrc on /root/target
<debug>  mount  -o bind /root/testsrc /root/target
[bind-mount.sh] mount  -o bind /root/testsrc /root/target
starting bg process to hold target file open
this is test file
starting bg process to hold target file open
this is test file
<debug>  Checking fs "testrsc", Level 
[bind-mount.sh] Checking fs "testrsc", Level 
<info>   unmounting /root/target
[bind-mount.sh] unmounting /root/target
umount: /root/target: device is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1))
<debug>  umount failed: 1
[bind-mount.sh] umount failed: 1
<warning>Sending SIGTERM to processes on /root/target
[bind-mount.sh] Sending SIGTERM to processes on /root/target
<info>   unmounting /root/target
[bind-mount.sh] unmounting /root/target
./bind-test_v3.sh: line 31: 17793 Terminated              tail -f "$target/testfile"
./bind-test_v3.sh: line 31: 17798 Terminated              tail -f "$tmpfile"
./bind-test_v3.sh: line 31: 17799 Terminated              tail -f "$tmpfile"
./bind-test_v3.sh: line 31: 17800 Terminated              tail -f "$tmpfile"
./bind-test_v3.sh: line 31: 17801 Terminated              tail -f "$target/testfile"
<debug>  Checking fs "testrsc", Level 
[bind-mount.sh] Checking fs "testrsc", Level 
<err>    default: /root/testsrc is not mounted on /root/target
[bind-mount.sh] default: /root/testsrc is not mounted on /root/target
PASSED

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHBA-2014-1428.html