[LTP] [PATCH] memcg/memcontrol04: Fix the judgment error in test_memcg_low()

[Andrea Cervesato]

Hi!

Thanks for checking this test, but did you take a look at the 
explanation given in the test "tags" ? -> 
https://bugzilla.suse.com/show_bug.cgi?id=1196298

Regards,
Andrea

On 11/21/24 04:05, Jin Guojie wrote:
> When running memcontrol04, TFAIL results will appear on various Linux
> distributions, kernel versions, and CPUs:
>
> (1) Test platform
>
> * Linux distribution: Ubuntu 24.10
> * CPU: X86_64, Arm64
> * Kernel: 6.6 longterm
> * glibc:  2.40
> * LTP version:  commit ec4161186e5, Oct 24 12:18:17 2024
>
> (2) Error logs
>
> During the operation of memcontrol04, file systems such as ext2, ext3,
> ext4, xfs, ntfs, and vfat will be tested.
> For any of the file system, the same TFAIL result will appear:
>
> root@vm:~/ltp/testcases/kernel/controllers/memcg# ./memcontrol04
>
> tst_test.c:1823: TINFO: === Testing on ext2 ===
> memcontrol04.c:208: TPASS: Expect: (C oom events=0) == 0
> memcontrol04.c:211: TPASS: Expect: (C low events=437) > 0
> memcontrol04.c:208: TPASS: Expect: (D oom events=0) == 0
> memcontrol04.c:211: TPASS: Expect: (D low events=437) > 0
> memcontrol04.c:208: TPASS: Expect: (E oom events=0) == 0
> memcontrol04.c:214: TPASS: Expect: (E low events=0) == 0
> memcontrol04.c:208: TPASS: Expect: (F oom events=0) == 0
> memcontrol04.c:214: TFAIL: Expect: (F low events=412) == 0
>
> tst_test.c:1823: TINFO: === Testing on ext3 ===
> memcontrol04.c:208: TPASS: Expect: (C oom events=0) == 0
> memcontrol04.c:211: TPASS: Expect: (C low events=437) > 0
> memcontrol04.c:208: TPASS: Expect: (D oom events=0) == 0
> memcontrol04.c:211: TPASS: Expect: (D low events=437) > 0
> memcontrol04.c:208: TPASS: Expect: (E oom events=0) == 0
> memcontrol04.c:214: TPASS: Expect: (E low events=0) == 0
> memcontrol04.c:208: TPASS: Expect: (F oom events=0) == 0
> memcontrol04.c:214: TFAIL: Expect: (F low events=411) == 0
>
> ......
>
> Summary:
> passed   55
> failed   5
> broken   0
> skipped  0
> warnings 0
>
> It looks like there is an error in the processing logic of cgroup F.
>
> (3) Cause analysis
>
> In the test_memcg_low() function, 4 subgroups (C, D, E, F) are created under B,
> and 50MB pagecache is allocated in C, D, and F. Therefore, when checking whether
> it is successful at the end, only E should be judged to have low_events==0,
> and the judgment conditions for all other subgroups should be low_events > 0.
>
> (4) Fix issure
>
> #1209
> https://github.com/linux-test-project/ltp/issues/1209
>
> Signed-off-by: Jin Guojie <guojie.jin@gmail.com>
>
> ---
>   testcases/kernel/controllers/memcg/memcontrol04.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/testcases/kernel/controllers/memcg/memcontrol04.c
> b/testcases/kernel/controllers/memcg/memcontrol04.c
> index 1b8d115f8..0dddb7449 100644
> --- a/testcases/kernel/controllers/memcg/memcontrol04.c
> +++ b/testcases/kernel/controllers/memcg/memcontrol04.c
> @@ -207,7 +207,7 @@ static void test_memcg_low(void)
>
>                  TST_EXP_EXPR(oom == 0, "(%c oom events=%ld) == 0", id, oom);
>
> -               if (i < E) {
> +               if (i != E) {
>                          TST_EXP_EXPR(low > 0,
>                                       "(%c low events=%ld) > 0", id, low);
>                  } else {
> --
> 2.45.2
>