Re: [RFC] 3.10 kernel- oom with about 24G free memory

[Michal Hocko]

On Thu 09-02-17 14:26:28, Michal Hocko wrote:
> On Thu 09-02-17 20:54:49, Yisheng Xie wrote:
> > Hi all,
> > I get an oom on a linux 3.10 kvm guest OS. when it triggers the oom
> > it have about 24G free memory(and host OS have about 10G free memory)
> > and watermark is sure ok.
> > 
> > I also check about about memcg limit value, also cannot find the
> > root cause.
> > 
> > Is there anybody ever meet similar problem and have any idea about it?
> > 
> > Any comment is more than welcome!
> > 
> > Thanks
> > Yisheng Xie
> > 
> > -------------
> > [   81.234289] DefSch0200 invoked oom-killer: gfp_mask=0xd0, order=0, oom_score_adj=0
> > [   81.234295] DefSch0200 cpuset=/ mems_allowed=0
> > [   81.234299] CPU: 3 PID: 8284 Comm: DefSch0200 Tainted: G           O E ----V-------   3.10.0-229.42.1.105.x86_64 #1
> > [   81.234301] Hardware name: OpenStack Foundation OpenStack Nova, BIOS rel-1.8.1-0-g4adadbd-20161111_105425-HGH1000008200 04/01/2014
> > [   81.234303]  ffff880ae2900000 000000002b3489d7 ffff880b6cec7c58 ffffffff81608d3d
> > [   81.234307]  ffff880b6cec7ce8 ffffffff81603d1c 0000000000000000 ffff880b6cd09000
> > [   81.234311]  ffff880b6cec7cd8 000000002b3489d7 ffff880b6cec7ce0 ffffffff811bdd77
> > [   81.234314] Call Trace:
> > [   81.234323]  [<ffffffff81608d3d>] dump_stack+0x19/0x1b
> > [   81.234327]  [<ffffffff81603d1c>] dump_header+0x8e/0x214
> > [   81.234333]  [<ffffffff811bdd77>] ? mem_cgroup_iter+0x177/0x2b0
> > [   81.234339]  [<ffffffff8115d83e>] check_panic_on_oom+0x2e/0x60
> > [   81.234342]  [<ffffffff811c17bf>] mem_cgroup_oom_synchronize+0x34f/0x580
> 
> OK, so this is a memcg OOM killer which panics because the configuration
> says so. The OOM report doesn't say so and that is the bug. dump_header
> is memcg aware and mem_cgroup_out_of_memory initializes oom_control
> properly. Is this Vanilla kernel?

I have only now noticed this is 3.10 rather than 4.10 kernel.

There we simply do
dump_header(NULL, gfp_mask, order, NULL, nodemask);

so memcg is NULL and that's why we report global counters. You need
2415b9f5cb04 ("memcg: print cgroup information when system panics due to
panic_on_oom")
-- 
Michal Hocko
SUSE Labs