[LTP] Issue faced in memcg_stat_rss while running mainline kernels between 6.7 and 6.8

[Harshvardhan Jha]

Hello Michal
On 16/01/25 1:23 PM, Michal Hocko wrote:
> Hi,
>
> On Wed 15-01-25 23:59:20, Petr Vorel wrote:
>> Hi Harshvardhan,
>>
>> [ Cc cgroups@vger.kernel.org: FYI problem in recent kernel using cgroup v1 ]
> It is hard to decypher the output and nail down actual failure. Could
> somebody do a TL;DR summary of the failure, since when it happens, is it
> really v1 specific?

The test ltp_memcg_stat_rss is indeed cgroup v1 specific.

The test started failing soon after this commit 7d7ef0a4686ab mm: memcg:
restore subtree stats flushing

This commit was part of a 5 patch series:
508bed884767a mm: memcg: change flush_next_time to flush_last_time
e0bf1dc859fdd mm: memcg: move vmstats structs definition above flushing code
8d59d2214c236 mm: memcg: make stats flushing threshold per-memcg
b006847222623 mm: workingset: move the stats flush into
workingset_test_recent()
7d7ef0a4686ab mm: memcg: restore subtree stats flushing

The test log returns this:

<<<test_start>>>
tag=memcg_stat_rss stime=1731755339
cmdline="memcg_stat_rss.sh"
contacts=""
analysis=exit
<<<test_output>>>
incrementing stop
memcg_stat_rss 1 TINFO: Running: memcg_stat_rss.sh
memcg_stat_rss 1 TINFO: Tested kernel: Linux harjha-ol9kdevltp
6.7.0-masterpost.2024111.el9.rc1.x86_64 #1 SMP PREEMPT_DYNAMIC Fri Nov
15 11:55:41 PST 2024 x86_64 x86_64 x86_64 GNU/Linux
memcg_stat_rss 1 TINFO: Using
/tempdir/ltp-G6cge4CkrR/LTP_memcg_stat_rss.1zrm6X02CO as tmpdir (xfs
filesystem)
memcg_stat_rss 1 TINFO: timeout per run is 0h 5m 0s
memcg_stat_rss 1 TINFO: set /sys/fs/cgroup/memory/memory.use_hierarchy
to 0 failed
memcg_stat_rss 1 TINFO: Setting shmmax
memcg_stat_rss 1 TINFO: Running memcg_process --mmap-anon -s 266240
memcg_stat_rss 1 TINFO: Warming up pid: 9083
memcg_stat_rss 1 TINFO: Process is still here after warm up: 9083
memcg_stat_rss 1 TFAIL: rss is 0, 266240 expected
memcg_stat_rss 1 TBROK: timed out on memory.usage_in_bytes 4096 266240
266240
/opt/ltp-20240930/testcases/bin/tst_test.sh: line 158:  9083
Killed                  memcg_process "$@"  (wd:
/sys/fs/cgroup/memory/ltp/test-9024/ltp_9024)

Summary:
passed   0
failed   1
broken   1
skipped  0
warnings 0
<<<execution_status>>>

It is important to note that the entire test suite didn't even execute
as the second test itself was broken.
The latest 6.12 also shows errors in this test suite upon explicitly
enabling cgroups v1.

Thanks & Regards,
Harshvardhan