[LTP] [PATCH] memcg_control_test: Disable swapping in test cgroup for v2

[Li Wang]

Patch merged, thanks!

On Fri, Mar 28, 2025 at 12:12 PM Li Wang <liwang@redhat.com> wrote:

>
>
> On Fri, Mar 28, 2025 at 4:01 AM T.J. Mercier via ltp <ltp@lists.linux.it>
> wrote:
>
>> memcg_control_test_1 sets both a memory limit and a memsw/swap limit to
>> a single page, and then asks mem_process to allocate 2 pages in an
>> attempt to cause a memcg OOM kill. However, if swapping is enabled the
>> first page can be swapped before the second is allocated causing neither
>> limit to be exceeded in v2 since there is no combined memsw counter in
>> v2. In this case no OOM kill will occur which results in a test failure.
>> Fix this by disabling swap in the test cgroup for v2 if swap is enabled,
>> causing both pages to always be accounted under the same counter such
>> that memory.max causes an OOM kill.
>>
>> Fixes: c0b815736 ("New testcase added by Naufal.")
>> Signed-off-by: T.J. Mercier <tjmercier@google.com>
>>
>
> Reviewed-by: Li Wang <liwang@redhat.com>
>
> ---
>>  .../memcg/control/memcg_control_test.sh            | 14 +++++++++++---
>>  1 file changed, 11 insertions(+), 3 deletions(-)
>>
>> diff --git
>> a/testcases/kernel/controllers/memcg/control/memcg_control_test.sh
>> b/testcases/kernel/controllers/memcg/control/memcg_control_test.sh
>> index 68287a70c..79b3a02a9 100644
>> --- a/testcases/kernel/controllers/memcg/control/memcg_control_test.sh
>> +++ b/testcases/kernel/controllers/memcg/control/memcg_control_test.sh
>> @@ -12,7 +12,6 @@ TST_NEEDS_TMPDIR=1
>>
>>  PAGE_SIZE=$(tst_getconf PAGESIZE)
>>
>> -TOT_MEM_LIMIT=$PAGE_SIZE
>>  ACTIVE_MEM_LIMIT=$PAGE_SIZE
>>  PROC_MEM=$((PAGE_SIZE * 2))
>>
>> @@ -50,13 +49,22 @@ test1()
>>
>>         # If the kernel is built without swap, the $memsw_memory_limit
>> file is missing
>>         if [ -e "$test_dir/$memsw_memory_limit" ]; then
>> -               ROD echo "$TOT_MEM_LIMIT" \>
>> "$test_dir/$memsw_memory_limit"
>> +               if [ "$cgroup_version" = "2" ]; then
>> +                       # v2 does not have a combined memsw limit like v1.
>> +                       # Disable swapping in v2 so all pages get
>> acccounted to the non-swap counter.
>> +                       SWAP_LIMIT=0
>> +               else
>> +                       # Swapping cannot be disabled via
>> memsw.limit_in_bytes in v1.
>> +                       # Apply a memsw limit in v1 to capture any
>> swapped pages
>> +                       SWAP_LIMIT=$ACTIVE_MEM_LIMIT
>> +               fi
>> +               ROD echo "$SWAP_LIMIT" \> "$test_dir/$memsw_memory_limit"
>>         fi
>>
>>         KILLED_CNT=0
>>         test_proc_kill
>>
>> -       if [ $PROC_MEM -gt $TOT_MEM_LIMIT ] && [ $KILLED_CNT -eq 0 ]; then
>> +       if [ $KILLED_CNT -eq 0 ]; then
>>                 tst_res TFAIL "Test #1: failed"
>>         else
>>                 tst_res TPASS "Test #1: passed"
>> --
>> 2.49.0.472.ge94155a9ec-goog
>>
>>
>> --
>> Mailing list info: https://lists.linux.it/listinfo/ltp
>>
>>
>
> --
> Regards,
> Li Wang
>


-- 
Regards,
Li Wang