[PATCH v2] doc: kselftest: update for clarity on running kselftests in CI rings

[Shuah Khan]

Update to add clarity and recommendations on running newer kselftests
on older kernels vs. matching the kernel and kselftest revisions.

The recommendation is "Match kernel revision and kselftest."

Signed-off-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
---
Changes since v1: Fixed "WARNING: Title underline too short."

 Documentation/dev-tools/kselftest.rst | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/Documentation/dev-tools/kselftest.rst b/Documentation/dev-tools/kselftest.rst
index 25604904fa6e..308506c5e8fa 100644
--- a/Documentation/dev-tools/kselftest.rst
+++ b/Documentation/dev-tools/kselftest.rst
@@ -12,6 +12,31 @@ write new tests using the framework on Kselftest wiki:
 
 https://kselftest.wiki.kernel.org/
 
+Recommendations on running kselftests in Continuous Integration test rings
+==========================================================================
+
+It is recommended that users run Kselftest from the same release. Running
+newer Kselftest on older kernels isn't recommended for the following
+reasons:
+
+- Kselftest from mainline and linux-next might not be stable enough to run
+  on stable kernels.
+- Kselftests detect feature dependencies at run-time and skip tests if a
+  feature and/or configuration they test aren't enabled. Running newer
+  tests on older kernels could result in a few too many skipped/failed
+  conditions. It becomes difficult to evaluate the results.
+- Newer tests provide better coverage. However, users should make a judgement
+  call on coverage vs. run to run consistency and being able to compare
+  run to run results on older kernels.
+
+Recommendations:
+
+Match kernel revision and kselftest. Especially important for LTS and
+Stable kernel Continuous Integration test rings.
+
+Hot-plug tests
+==============
+
 On some systems, hot-plug tests could hang forever waiting for cpu and
 memory to be ready to be offlined. A special hot-plug target is created
 to run the full range of hot-plug tests. In default mode, hot-plug tests run
-- 
2.20.1