Implement basic functionality to support cgroup tracking.  Each cgroup
can be identified by inode number which can be read from userspace too.
The actual cgroup processing will come in the later patch.
Reported-by: Nkernel test robot <rong.a.chen@intel.com>
Signed-off-by: NNamhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
[ fix perf test failure on sampling parsing ]
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20200325124536.2800725-4-namhyung@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>