| Message ID | 20210305222714.257839-1-msys.mizuma@gmail.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | memcg: memcg_subgroup_charge.sh: Fix the parent memory limit | expand |
Hi, On 3/5/2021 11:27 PM, Masayoshi Mizuma wrote: > From: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com> > > memcg_subgroup_charge.sh fails on v5.9 and later kernel. > That's because memory.limit_in_bytes isn't set the suitable value > so mem_process is killed by OOM accidentally. > > The memory.limit_in_bytes is now wrong value because commit > 3e38e0aaca9e ("mm: memcg: charge memcg percpu memory to the parent cgroup") > changed the charging memory usage. The percpu memory, which is > needed to create the subgroup, is charged to the parent's usage. > > Since we can get the amount of the percpu memory as memory.usage_in_bytes > after the subgroup is created, extend the limit to limit_in_bytes + usage_in_bytes. Sounds reasonable, I guess the test always fails on 5.9? But the problem is, this test also fails on older kernels sometimes. When I looked at this the last time, I thought it was because sometimes the kernel requires new pages for the page table and that is also taken into account for the memory limit. I still don't know why the test even sets a limit for the parent group and would vote for completely removing the memory setting on the parent. Jörg
diff --git a/testcases/kernel/controllers/memcg/functional/memcg_subgroup_charge.sh b/testcases/kernel/controllers/memcg/functional/memcg_subgroup_charge.sh index 9b23177a4..512a4e3dd 100755 --- a/testcases/kernel/controllers/memcg/functional/memcg_subgroup_charge.sh +++ b/testcases/kernel/controllers/memcg/functional/memcg_subgroup_charge.sh @@ -20,9 +20,16 @@ TST_CNT=3 test_subgroup() { mkdir subgroup - echo $1 > memory.limit_in_bytes echo $2 > subgroup/memory.limit_in_bytes + # v5.9 and later kernel, percpu memory which is needed to create + # the subgroup is charged to the parent's usage. + # Extend the parent limit so that we can observe the rss of + # memcg_process correctly. + pre_used=$(cat memory.usage_in_bytes) + newlimit=$(( $1 + pre_used )) + echo $newlimit > memory.limit_in_bytes + start_memcg_process --mmap-anon -s $PAGESIZES warmup