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

Naoya Horiguchi
2014-07-16T20:11:47Z

On Wed, Jul 16, 2014 at 03:57:21PM -0400, Johannes Weiner wrote:
> 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?

Sorry for confusion, but yes. I used my own localversion,
but this kernel is mmotm-2014-07-09-17-08 (git-describe says
mmotm-2014-07-09-17-08-3-gcb8370a1d76e.)

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

I'll try this kernel.
If that passes, this problem is fixed implicitly, so that's fine :)