linux-kernel - Re: [PATCH v11 1/2] Refactor part of the oom report in dump

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Date:   Wed, 4 Jul 2018 10:25:30 +0800
From:   禹舟键 <ufo19890607@...il.com>
To:     andy.shevchenko@...il.com
Cc:     akpm@...ux-foundation.org, mhocko@...e.com, rientjes@...gle.com,
        kirill.shutemov@...ux.intel.com, aarcange@...hat.com,
        penguin-kernel@...ove.sakura.ne.jp, guro@...com,
        yang.s@...baba-inc.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Wind Yu <yuzhoujian@...ichuxing.com>
Subject: Re: [PATCH v11 1/2] Refactor part of the oom report in dump_header

Hi Andy
The const char array need to be used by the new func
mem_cgroup_print_oom_context and some funcs in oom_kill.c in the
second patch.

Thanks

>
> On Sat, Jun 30, 2018 at 7:38 PM,  <ufo19890607@...il.com> wrote:
> > From: yuzhoujian <yuzhoujian@...ichuxing.com>
> >
> > The current system wide oom report prints information about the victim
> > and the allocation context and restrictions. It, however, doesn't
> > provide any information about memory cgroup the victim belongs to. This
> > information can be interesting for container users because they can find
> > the victim's container much more easily.
> >
> > I follow the advices of David Rientjes and Michal Hocko, and refactor
> > part of the oom report. After this patch, users can get the memcg's
> > path from the oom report and check the certain container more quickly.
> >
> > The oom print info after this patch:
> > oom-kill:constraint=<constraint>,nodemask=<nodemask>,oom_memcg=<memcg>,task_memcg=<memcg>,task=<comm>,pid=<pid>,uid=<uid>
>
>
> > +static const char * const oom_constraint_text[] = {
> > +       [CONSTRAINT_NONE] = "CONSTRAINT_NONE",
> > +       [CONSTRAINT_CPUSET] = "CONSTRAINT_CPUSET",
> > +       [CONSTRAINT_MEMORY_POLICY] = "CONSTRAINT_MEMORY_POLICY",
> > +       [CONSTRAINT_MEMCG] = "CONSTRAINT_MEMCG",
> > +};
>
> I'm not sure why we have this in the header.
>
> This produces a lot of noise when W=1.
>
> In file included from
> /home/andy/prj/linux-topic-mfld/include/linux/memcontrol.h:31:0,
>                 from /home/andy/prj/linux-topic-mfld/include/net/sock.h:58,
>                 from /home/andy/prj/linux-topic-mfld/include/linux/tcp.h:23,
>                 from /home/andy/prj/linux-topic-mfld/include/linux/ipv6.h:87,
>                 from /home/andy/prj/linux-topic-mfld/include/net/ipv6.h:16,
>                 from
> /home/andy/prj/linux-topic-mfld/net/ipv4/netfilter/nf_log_ipv4.c:17:
> /home/andy/prj/linux-topic-mfld/include/linux/oom.h:32:27: warning:
> ‘oom_constraint_text’ defined but not used [-W
> unused-const-variable=]
> static const char * const oom_constraint_text[] = {
>                           ^~~~~~~~~~~~~~~~~~~
>  CC [M]  net/ipv4/netfilter/iptable_nat.o
>
>
> If you need (but looking at the code you actually don't if I didn't
> miss anything) it in several places, just export.
> Otherwise put it back to memcontrol.c.
>
> --
> With Best Regards,
> Andy Shevchenko