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

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Message-ID: <CAHCio2h1G5UDRv_veWbzRAMtM+NheyVfsghoC3G80BJgOtuW7g@mail.gmail.com>
Date:   Tue, 3 Jul 2018 18:57:14 +0800
From:   禹舟键 <ufo19890607@...il.com>
To:     mhocko@...nel.org
Cc:     akpm@...ux-foundation.org, 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 Michal
cpuset_print_current_mems_allowed is also invoked by
warn_alloc(page_alloc.c). So, can I remove the current->comm output in
the pr_info ?

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index d8b12e0d39cd..09b8ef6186c6 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -2666,9 +2666,9 @@ void cpuset_print_current_mems_allowed(void)
        rcu_read_lock();

        cgrp = task_cs(current)->css.cgroup;
-       pr_info("%s cpuset=", current->comm);
+       pr_info(",cpuset=");
        pr_cont_cgroup_name(cgrp);
-       pr_cont(" mems_allowed=%*pbl\n",
+       pr_cont(",mems_allowed=%*pbl",
                nodemask_pr_args(&current->mems_allowed));
>
> On Sun 01-07-18 00:38:58, 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>
>
> This changelog doesn't correspond to the patch. Also while we were
> discussing this off-list, I have suggested to pull the cpuset info into
> the single line output.
>
> What about the following?
> "
> OOM report contains several sections. The first one is the allocation
> context that has triggered the OOM. Then we have cpuset context
> followed by the stack trace of the OOM path. Followed by the oom
> eligible tasks and the information about the chosen oom victim.
>
> One thing that makes parsing more awkward than necessary is that we do
> not have a single and easily parsable line about the oom context. This
> patch is reorganizing the oom report to
> 1) who invoked oom and what was the allocation request
>         [  126.168182] panic invoked oom-killer: gfp_mask=0x6280ca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), order=0, oom_score_adj=0
>
> 2) OOM stack trace
>         [  126.169806] CPU: 23 PID: 8668 Comm: panic Not tainted 4.18.0-rc2+ #36
>         [  126.170494] Hardware name: Inspur SA5212M4/YZMB-00370-107, BIOS 4.1.10 11/14/2016
>         [  126.171197] Call Trace:
>         [  126.171901]  dump_stack+0x5a/0x73
>         [  126.172593]  dump_header+0x58/0x2dc
>         [  126.173294]  oom_kill_process+0x228/0x420
>         [  126.173999]  ? oom_badness+0x2a/0x130
>         [  126.174705]  out_of_memory+0x11a/0x4a0
>         [  126.175415]  __alloc_pages_slowpath+0x7cc/0xa1e
>         [  126.176128]  ? __alloc_pages_slowpath+0x194/0xa1e
>         [  126.176853]  ? page_counter_try_charge+0x54/0xc0
>         [  126.177580]  __alloc_pages_nodemask+0x277/0x290
>         [  126.178319]  alloc_pages_vma+0x73/0x180
>         [  126.179058]  do_anonymous_page+0xed/0x5a0
>         [  126.179825]  __handle_mm_fault+0xbb3/0xe70
>         [  126.180566]  handle_mm_fault+0xfa/0x210
>         [  126.181313]  __do_page_fault+0x233/0x4c0
>         [  126.182063]  do_page_fault+0x32/0x140
>         [  126.182812]  ? page_fault+0x8/0x30
>         [  126.183560]  page_fault+0x1e/0x30
>
> 3) oom context (contrains and the chosen victim)
>         [  126.190619] oom-kill:constraint=CONSTRAINT_NONE,nodemask=(null),cpuset=/,mems_allowed=0-1,task=panic,pid= 8673,uid=    0
>
> An admin can easily get the full oom context at a single line which
> makes parsing much easier.
> "
> --
> Michal Hocko
> SUSE Labs