Shuah,

Can you take this through your urgent branch?

-- Steve

On Tue, 28 Oct 2025 12:27:24 -0400 Steven Rostedt rostedt@goodmis.org wrote:

From: Steven Rostedt rostedt@goodmis.org

The tracing selftest "event-filter-function.tc" was failing because it first runs the "sample_events" function that triggers the kmem_cache_free event and it looks at what function was used during a call to "ls".

But the first time it calls this, it could trigger events that are used to pull pages into the page cache.

The rest of the test uses the function it finds during that call to see if it will be called in subsequent "sample_events" calls. But if there's no need to pull pages into the page cache, it will not trigger that function and the test will fail.

Call the "sample_events" twice to trigger all the page cache work before it calls it to find a function to use in subsequent checks.

Cc: stable@vger.kernel.org Fixes: eb50d0f250e96 ("selftests/ftrace: Choose target function for filter test from samples") Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org

---

.../selftests/ftrace/test.d/filter/event-filter-function.tc | 4 ++++ 1 file changed, 4 insertions(+)

diff --git a/tools/testing/selftests/ftrace/test.d/filter/event-filter-function.tc b/tools/testing/selftests/ftrace/test.d/filter/event-filter-function.tc index c62165fabd0c..003f612f57b0 100644 --- a/tools/testing/selftests/ftrace/test.d/filter/event-filter-function.tc +++ b/tools/testing/selftests/ftrace/test.d/filter/event-filter-function.tc @@ -20,6 +20,10 @@ sample_events() { echo 0 > tracing_on echo 0 > events/enable +# Clear functions caused by page cache; run sample_events twice +sample_events +sample_events

echo "Get the most frequently calling function" echo > trace sample_events

On Tue, 28 Oct 2025 12:27:24 -0400 Steven Rostedt rostedt@goodmis.org wrote:

From: Steven Rostedt rostedt@goodmis.org

The tracing selftest "event-filter-function.tc" was failing because it first runs the "sample_events" function that triggers the kmem_cache_free event and it looks at what function was used during a call to "ls".

But the first time it calls this, it could trigger events that are used to pull pages into the page cache.

The rest of the test uses the function it finds during that call to see if it will be called in subsequent "sample_events" calls. But if there's no need to pull pages into the page cache, it will not trigger that function and the test will fail.

Call the "sample_events" twice to trigger all the page cache work before it calls it to find a function to use in subsequent checks.

Looks good to me.

Acked-by: Masami Hiramatsu (Google) mhiramat@kernel.org

Thanks,

Cc: stable@vger.kernel.org Fixes: eb50d0f250e96 ("selftests/ftrace: Choose target function for filter test from samples") Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org

---

.../selftests/ftrace/test.d/filter/event-filter-function.tc | 4 ++++ 1 file changed, 4 insertions(+)

diff --git a/tools/testing/selftests/ftrace/test.d/filter/event-filter-function.tc b/tools/testing/selftests/ftrace/test.d/filter/event-filter-function.tc index c62165fabd0c..003f612f57b0 100644 --- a/tools/testing/selftests/ftrace/test.d/filter/event-filter-function.tc +++ b/tools/testing/selftests/ftrace/test.d/filter/event-filter-function.tc @@ -20,6 +20,10 @@ sample_events() { echo 0 > tracing_on echo 0 > events/enable +# Clear functions caused by page cache; run sample_events twice +sample_events +sample_events

echo "Get the most frequently calling function" echo > trace sample_events -- 2.51.0