cgrulesengd cannot process symlinked executables

[ojab]

Oh hai!

I've found that 0.37.1-1ubuntu10 in precise/LTS cannot process symlinked executables correctly, the testcase is
>$ python -c "import time; time.sleep(2)" & cgclassify $!
>Error in determining process name of pid 9738

The issue was fixed upstream in v0.38, see https://sourceforge.net/p/libcg/libcg/ci/acbed86127d5d81d082fa5b90cac13a4f84f877e

It will be awesome if the patch will be applied to v0.37 in precise/LTS, because right now cgrulesengd/cgclassify are basically unusable.

==============================
SRU Justification:
1. Impact: symlinked executables cannot be classified
2. Development fix: in the case of a symlink, read the real
   file path from /proc/self/exe
3. Stable fix: cherrypick small patch from development fix.
4. Test case: see comment #5.
5. Regression potential: there should be none, as this fix is
   taken straight from upstream and only affects the path when
   a symbolic link is being run (which is already broken).
==============================

[Serge Hallyn (serge-hallyn)]

Thanks for reporting this bug and pointing to the nice simple fix. I"ll work on SRUing this.

Would you mind adding a detailed test case to the description? (The symlinking part is fine, but the configuration file plus a neat way to determine that the task failed to be reclassified.)

[Serge Hallyn (serge-hallyn)]

@Jon,

I'm only allowed to nominate this bug for precise. Could you please accept the nomination, and, if you have time, complete the SRU (else shout and I'll continue with it).

[Jon Bernard (jbernard)]

@Serge I see your nomination, but it's unclear to me how to accept it. Can you give me a pointer?

[ojab (ojab)]

Sorry for delay, simple testcase:

sudo cgcreate -g memory:/
sudo cgcreate -g memory:/test
echo "`whoami`:python2.7 memory test/" | sudo tee -a /etc/cgrules.conf
/usr/bin/env python -c "import time; time.sleep(2)" &
export PID=$!
sudo cgclassify $PID
grep $PID /sys/fs/cgroup/memory/{,*/}cgroup.procs

In case of fixed libcgroup output will be something like
>/sys/fs/cgroup/memory/test/cgroup.procs:5778

Right now it is
>Error in determining process name of pid 2042
>/sys/fs/cgroup/memory/sysdefault/cgroup.procs:2042

[Serge Hallyn (serge-hallyn)]

Thanks, ojab - tried out your testcase, worked like a charm. (For manual reproduction, I'd recommend sleeping 20 rather than 2)

[Brian Murray (brian-murray)]

Hello ojab, or anyone else affected,

Accepted libcgroup into precise-proposed. The package will build now and be available at http://launchpad.net/ubuntu/+source/libcgroup/0.37.1-1ubuntu10.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, and change the tag from verification-needed to verification-done. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[ojab (ojab)]

The issue is fixed in libcgroup1/cgroup-bin-0.37.1-1ubuntu10.1.

[Launchpad Janitor (janitor)]

This bug was fixed in the package libcgroup - 0.37.1-1ubuntu10.1

---------------
libcgroup (0.37.1-1ubuntu10.1) precise-proposed; urgency=low

  * debian/patches/libcgroup_sumlinked_bin.patch: fix handling of symlinked
    executables. (LP: #1188850)
 -- Serge Hallyn <email address hidden> Wed, 12 Jun 2013 08:46:20 -0500

[Colin Watson (cjwatson)]

The verification of this Stable Release Update has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regresssions.