[LTP] [PATCH] memcg_subgroup_charge: Remove memory limitation

[Richard Palethorpe]

Hello,

Joerg Vehlow <lkml@jv-coder.de> writes:

> Hi,
>
> a little ping for this patch?
> I recently updated the ltp suite for our tests to 20200930 and stumbled 
> over this error again.
> Any reason for not applying it?

If there was no response it's safe to assume it was forgotten
about. Thanks for bumping it.

>
> Jörg
>
> On 11/6/2019 7:18 AM, Joerg Vehlow wrote:
>> From: Joerg Vehlow <joerg.vehlow@aox-tech.de>
>>
>> The test is supposed to verify, that memory used by a task
>> is not migrated to a subgroup, when the task is migrated.
>> In order to test this, it is not required, to limit
>> the memory at all, because accounting is done anyway and
>> the test checks the memory statistics.
>>
>> Therefore all memory limiting is removed. This also gets
>> rid of a faulty assumption when writing the test:
>> The test allocates 33 pages using mmap. It is expected,
>> that it does not need more than 33 * pagesize of memory.
>> But sometimes the kernel has to allocate new page tables.
>> This is accounted as kmem AND user memory.
>> (See kernel doc cgroup-v1/memory.txt section 2.7)
>> If this happend, the test failed, if the system has no swap,
>> because the oom killer kills the process.

Perhaps they were checking for side effects from setting the limit... I
think though it is correct to remove these limits.

Both check_stat lines are suspect to me as some unrelated tasklet could
run in the processes context and allocate some memory. Possibly this
should be converted to only an approximate check?

>>
>> Signed-off-by: Joerg Vehlow <joerg.vehlow@aox-tech.de>
>> ---
>>   .../kernel/controllers/memcg/functional/memcg_lib.sh |  4 ----
>>   .../memcg/functional/memcg_subgroup_charge.sh        | 12 +-----------
>>   2 files changed, 1 insertion(+), 15 deletions(-)
>>
>> diff --git a/testcases/kernel/controllers/memcg/functional/memcg_lib.sh b/testcases/kernel/controllers/memcg/functional/memcg_lib.sh
>> index aadaae4d2..aec8a00ab 100755
>> --- a/testcases/kernel/controllers/memcg/functional/memcg_lib.sh
>> +++ b/testcases/kernel/controllers/memcg/functional/memcg_lib.sh
>> @@ -404,13 +404,9 @@ test_hugepage()
>>   }
>>   
>>   # Test the memory charge won't move to subgroup
>> -# $1 - memory.limit_in_bytes in parent group
>> -# $2 - memory.limit_in_bytes in sub group
>>   test_subgroup()
>>   {
>>   	mkdir subgroup
>> -	echo $1 > memory.limit_in_bytes
>> -	echo $2 > subgroup/memory.limit_in_bytes
>>   
>>   	tst_resm TINFO "Running memcg_process --mmap-anon -s $PAGESIZES"
>>   	memcg_process --mmap-anon -s $PAGESIZES &
>> diff --git a/testcases/kernel/controllers/memcg/functional/memcg_subgroup_charge.sh b/testcases/kernel/controllers/memcg/functional/memcg_subgroup_charge.sh
>> index 9b11f7b58..98e5ad68d 100755
>> --- a/testcases/kernel/controllers/memcg/functional/memcg_subgroup_charge.sh
>> +++ b/testcases/kernel/controllers/memcg/functional/memcg_subgroup_charge.sh
>> @@ -26,7 +26,7 @@
>>   ################################################################################
>>   
>>   TCID="memcg_subgroup_charge"
>> -TST_TOTAL=3
>> +TST_TOTAL=1
>>   
>>   . memcg_lib.sh
>>   
>> @@ -36,15 +36,5 @@ testcase_1()
>>   	test_subgroup $PAGESIZES $((2*PAGESIZES))
>>   }
>>   
>> -testcase_2()
>> -{
>> -	test_subgroup $PAGESIZES $PAGESIZES
>> -}
>> -
>> -testcase_3()
>> -{
>> -	test_subgroup $PAGESIZES 0
>> -}
>> -
>>   run_tests
>>   tst_exit


-- 
Thank you,
Richard.