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Description of problem:
 The "task_cwd_path" tapset function can result in a memory leak. The function calls get_task_struct(task) early on, but does not have a corresponding put_task_struct() if the task->fs member is present.

Version-Release number of selected component (if applicable):
 systemtap-3.0-7.el7.x86_64

How reproducible:
 Easily

Steps to Reproduce:
1. Install systemtap required packages
2. Run the following script for a short interval

    $ stap -e 'probe kprocess.exit {path=fullpath_struct_path(task_cwd_path(task_current()));printf("%s\n", path)}'

3. Monitor the "KernelStack" field in /proc/meminfo over time

Actual results:
 The "KernelStack" counter continually increases

Expected results:
 The "KernelStack" counter increases and decreases as task_structs are created/freed.

Additional info:

Created attachment 1239984 [details]
Patch to issue a "put_task_struct" if needed prior to the return operation.

Thanks a lot, Kyle, merged your patch upstream, and should be in the rhel7.4 rebase.

@Frank,

No problem at all! Thank you for the merge!

- Kyle Walker

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.

https://access.redhat.com/errata/RHBA-2017:2301