Re: memcg swap doesn't work in mmotm-2014-07-09-17-08?

Johannes Weiner
2014-07-16T19:57:21Z

On Wed, Jul 16, 2014 at 03:31:29PM -0400, Naoya Horiguchi wrote:
> On Wed, Jul 16, 2014 at 02:37:27PM -0400, Johannes Weiner wrote:
> > On Wed, Jul 16, 2014 at 02:10:07PM -0400, Naoya Horiguchi wrote:
> > > Hi,
> > >
> > > It seems that when a process in some memcg tries to allocate more than
> > > memcg.limit_in_bytes, oom happens instead of swaping out in
> > > mmotm-2014-07-09-17-08 (memcg.memsw.limit_in_bytes is large enough).
> > > It does work in v3.16-rc3, so I think latest patches changed something.
> > > I'm not familiar with memcg internally, so no idea about what caused it.
> > > Could you see the problem?
> >
> > There are a lot of changes in memory and swap accounting, but I can
> > not reproduce what you are describing: I set up a cgroup with a 100MB
> > memory limit and an unlimited memory+swap, then start a task in there
> > that faults 200MB worth of anonymous pages. The result is 100MB in
> > memory, 100MB in swap:
>
> Hmm, this is almost the same test condition.
>
> > cache 0
> > rss 104267776
> > rss_huge 0
> > mapped_file 0
> > writeback 0
> > swap 105545728
> > pgpgin 26367
> > pgpgout 25950
> > pgfault 26695
> > pgmajfault 32
> > inactive_anon 52285440
> > active_anon 51982336
> > inactive_file 0
> > active_file 0
> > unevictable 0
> > hierarchical_memory_limit 104857600
> > hierarchical_memsw_limit 18446744073709551615
> >
> > Filename Type Size Used Priority
> > /swapfile file 8388604 109800 -1
> >
> > Could you provide more detail on your configuration and test case?
>
> What I did is like this:
>
> [root@test_140715-0036 ~]# cat tmp_memcg_swap.sh
> cgcreate -g memory:test1
> cgset -r memory.limit_in_bytes=0x1000000 test1 # 16 MB
> cgset -r memory.memsw.limit_in_bytes=0x4000000 test1 # 64 MB
> cgget -g memory:test1
> swapon -s
> cgexec -g memory:test1 memhog -r1 20m # alloc 20 MB

Okay, I tried with the smaller parameters that you use, but still
couldn't reproduce it:

cache 32768
rss 15867904
rss_huge 0
mapped_file 0
writeback 0
swap 5222400
pgpgin 1725
pgpgout 1420
pgfault 2015
pgmajfault 7
inactive_anon 10133504
active_anon 5726208
inactive_file 32768
active_file 0
unevictable 0
hierarchical_memory_limit 16777216
hierarchical_memsw_limit 67108864

16M in memory, 5M in swap, no OOM kills.

> then output is like this:
>
> [root@test_140715-0036 ~]# bash tmp_memcg_swap.sh
> test1:
> memory.pressure_level:
> memory.kmem.max_usage_in_bytes: 0
> memory.use_hierarchy: 1
> memory.swappiness: 60
> memory.memsw.failcnt: 0
> memory.limit_in_bytes: 16777216
> memory.memsw.max_usage_in_bytes: 0
> memory.usage_in_bytes: 0
> memory.memsw.limit_in_bytes: 67108864
> memory.failcnt: 0
> memory.kmem.limit_in_bytes: 18446744073709551615
> memory.force_empty:
> memory.kmem.slabinfo:
> memory.memsw.usage_in_bytes: 0
> memory.max_usage_in_bytes: 0
> memory.numa_stat: total=0 N0=0 N1=0 N2=0 N3=0
> file=0 N0=0 N1=0 N2=0 N3=0
> anon=0 N0=0 N1=0 N2=0 N3=0
> unevictable=0 N0=0 N1=0 N2=0 N3=0
> hierarchical_total=0 N0=0 N1=0 N2=0 N3=0
> hierarchical_file=0 N0=0 N1=0 N2=0 N3=0
> hierarchical_anon=0 N0=0 N1=0 N2=0 N3=0
> hierarchical_unevictable=0 N0=0 N1=0 N2=0 N3=0
> memory.kmem.tcp.limit_in_bytes: 18446744073709551615
> memory.oom_control: oom_kill_disable 0
> under_oom 0
> memory.kmem.tcp.max_usage_in_bytes: 0
> memory.kmem.failcnt: 0
> memory.kmem.usage_in_bytes: 0
> memory.stat: cache 0
> rss 0
> rss_huge 0
> mapped_file 0
> writeback 0
> swap 0
> pgpgin 0
> pgpgout 0
> pgfault 0
> pgmajfault 0
> inactive_anon 0
> active_anon 0
> inactive_file 0
> active_file 0
> unevictable 0
> hierarchical_memory_limit 16777216
> hierarchical_memsw_limit 67108864
> total_cache 0
> total_rss 0
> total_rss_huge 0
> total_mapped_file 0
> total_writeback 0
> total_swap 0
> total_pgpgin 0
> total_pgpgout 0
> total_pgfault 0
> total_pgmajfault 0
> total_inactive_anon 0
> total_active_anon 0
> total_inactive_file 0
> total_active_file 0
> total_unevictable 0
> recent_rotated_anon 0
> recent_rotated_file 0
> recent_scanned_anon 0
> recent_scanned_file 0
> memory.kmem.tcp.usage_in_bytes: 0
> memory.move_charge_at_immigrate: 0
> memory.soft_limit_in_bytes: 18446744073709551615
> memory.kmem.tcp.failcnt: 0
>
> Filename Type Size Used Priority
> /root/page_table_walker/swapfile file 40956 0 -1
> ..tmp_memcg_swap.sh: line 7: 1250 Killed cgexec -g memory:test1 memhog -r1 20m
>
> Kernel message is like this:
>
> [ 425.290261] memhog invoked oom-killer: gfp_mask=0xd0, order=0, oom_score_adj=0
> [ 425.291356] memhog cpuset=/ mems_allowed=0-3
> [ 425.291992] CPU: 2 PID: 1234 Comm: memhog Not tainted 3.15.0-140716-1501-00003-gcb8370a1d76e #268

That's not mmotm-2014-07-09-17-08, though, is it?

I was running on 3.16.0-rc5-mm1-00480-gab7ca1e1e407 (latest mmots).