[LTP] [PATCH] perf_event_open: improve the memory leak detection

[Li Wang]

On Fri, Jul 5, 2024 at 11:15 AM Li Wang <liwang@redhat.com> wrote:

> The goal is to add more robust memory leak detection by periodically
> sampling memory availability during the test run and checking for
> significant decreases in available memory.
>
> To avoid false postive:
>   perf_event_open03.c:95: TFAIL: Likely kernel memory leak detected
>
> Signed-off-by: Li Wang <liwang@redhat.com>
> ---
>  .../perf_event_open/perf_event_open03.c       | 32 +++++++++++++++----
>  1 file changed, 26 insertions(+), 6 deletions(-)
>
> diff --git a/testcases/kernel/syscalls/perf_event_open/perf_event_open03.c
> b/testcases/kernel/syscalls/perf_event_open/perf_event_open03.c
> index 7dd31d3d2..1aab43e82 100644
> --- a/testcases/kernel/syscalls/perf_event_open/perf_event_open03.c
> +++ b/testcases/kernel/syscalls/perf_event_open/perf_event_open03.c
> @@ -26,6 +26,7 @@
>  const int iterations = 12000000;
>  static int fd = -1;
>  static int runtime;
> +static int sample;
>
>  static void setup(void)
>  {
> @@ -77,22 +78,41 @@ static void check_progress(int i)
>
>  static void run(void)
>  {
> -       long diff;
> +       long diff, diff_total, mem_avail, mem_avail_prev;
>         int i;
>
> -       diff = SAFE_READ_MEMINFO("MemAvailable:");
> +       sample = 0;
> +       diff_total = 0;
> +
> +       mem_avail_prev = SAFE_READ_MEMINFO("MemAvailable:");
>         tst_timer_start(CLOCK_MONOTONIC);
>
>         /* leak about 100MB of RAM */
>         for (i = 0; i < iterations; i++) {
>                 ioctl(fd, PERF_EVENT_IOC_SET_FILTER, "filter,0/0@abcd");
>                 check_progress(i);
> -       }
>
> -       diff -= SAFE_READ_MEMINFO("MemAvailable:");
> +               /*
> +                * Every 1200000 iterations, calculate the difference in
> memory
> +                * availability. If the difference is greater than 10 *
> 1024 (10MB),
> +                * increment the sample counter and log the event.
> +                */
> +               if ((i % 1200000) == 0) {
> +                       mem_avail = SAFE_READ_MEMINFO("MemAvailable:");
> +                       diff = mem_avail_prev - mem_avail;
> +                       diff_total += diff;
> +
> +                       if (diff > 20 * 1024) {
> +                               sample++;
> +                               tst_res(TINFO, "MemAvailable decreased by
> %ld kB at iteration %d", diff, i);
> +                       }
> +
> +                       mem_avail_prev = mem_avail;
> +               }
> +       }
>
> -       if (diff > 50 * 1024)
> -               tst_res(TFAIL, "Likely kernel memory leak detected");
> +       if ((sample > 5) || (diff_total > 100 * 1024))
>


Here maybe diff_toal is still the interference factor in reporting false
positives,
I'm hesitating to remove or keep it.

Or we could use it first to see how the test performs in the large-scale CI
testing.



> +               tst_res(TFAIL, "Likely kernel memory leak detected, total
> decrease: %ld kB", diff_total);
>         else
>                 tst_res(TPASS, "No memory leak found");
>  }
> --
> 2.45.2
>
>
> --
> Mailing list info: https://lists.linux.it/listinfo/ltp
>
>

-- 
Regards,
Li Wang