@@ -19,9 +19,21 @@ TST_CNT=3
# $2 - memory.limit_in_bytes in sub group
test_subgroup()
{
+ local limit_parent=$1
+ local limit_subgroup=$2
+
+ # OOM might start killing if memory usage is 100%, so give it
+ # always one page size more:
+ if [ $limit_parent -ne 0 ]; then
+ limit_parent=$((limit_parent + PAGESIZE))
+ fi
+ if [ $limit_subgroup -ne 0 ]; then
+ limit_subgroup=$((limit_subgroup + PAGESIZE))
+ fi
+
mkdir subgroup
- echo $1 > memory.limit_in_bytes
- echo $2 > subgroup/memory.limit_in_bytes
+ echo $limit_parent > memory.limit_in_bytes
+ echo $limit_subgroup > subgroup/memory.limit_in_bytes
start_memcg_process --mmap-anon -s $PAGESIZES
The memcg_subgroup_charge was failing on kernel v5.8 in around 10% cases with: memcg_subgroup_charge 1 TINFO: Running memcg_process --mmap-anon -s 135168 memcg_subgroup_charge 1 TINFO: Warming up pid: 19289 memcg_subgroup_charge 1 TINFO: Process is still here after warm up: 19289 memcg_subgroup_charge 1 TFAIL: rss is 0, 135168 expected memcg_subgroup_charge 1 TPASS: rss is 0 as expected In dmesg one could see that OOM killer killed the process even though group memory limit was matching the usage: memcg_process invoked oom-killer: gfp_mask=0xcc0(GFP_KERNEL), order=0, oom_score_adj=0 CPU: 4 PID: 19289 Comm: memcg_process Not tainted 5.8.0-1031-oracle #32~20.04.2-Ubuntu Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.4.1 12/03/2020 ... memory: usage 132kB, limit 132kB, failcnt 9 memory+swap: usage 132kB, limit 9007199254740988kB, failcnt 0 kmem: usage 4kB, limit 9007199254740988kB, failcnt 0 ... Tasks state (memory values in pages): [ pid ] uid tgid total_vm rss pgtables_bytes swapents oom_score_adj name [ 19289] 0 19289 669 389 40960 0 0 memcg_process oom-kill:constraint=CONSTRAINT_MEMCG,nodemask=(null),cpuset=/,mems_allowed=0,oom_memcg=/ltp_19257,task_memcg=/ltp_19257,task=memcg_process,pid=19289,uid=0 Memory cgroup out of memory: Killed process 19289 (memcg_process) total-vm:2676kB, anon-rss:84kB, file-rss:1468kB, shmem-rss:4kB, UID:0 pgtables:40kB oom_score_adj:0 oom_reaper: reaped process 19289 (memcg_process), now anon-rss:0kB, file-rss:0kB, shmem-rss:4kB It seems using 100% of memory assigned to given group might trigger OOM, so add a space of at least one page. Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com> --- .../memcg/functional/memcg_subgroup_charge.sh | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-)