linux-kernel - Re: [PATCH v3] mm/oom_kill: show oom eligibility when displaying the current memory state of all tasks

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Message-ID: <20210802145041.w7lqdt77qguwbwag@ava.usersys.com>
Date:   Mon, 2 Aug 2021 15:50:41 +0100
From:   Aaron Tomlin <atomlin@...hat.com>
To:     David Rientjes <rientjes@...gle.com>
Cc:     linux-mm@...ck.org, akpm@...ux-foundation.org, mhocko@...e.com,
        penguin-kernel@...ove.sakura.ne.jp, llong@...hat.com,
        neelx@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] mm/oom_kill: show oom eligibility when displaying the
 current memory state of all tasks

On Sun 2021-08-01 20:49 -0700, David Rientjes wrote:
> oom_score_adj is shown already in the tasklist dump, I'm not sure what 
> value this adds.

Fair enough.

> 
> > +	else if (test_bit(MMF_OOM_SKIP, &p->mm->flags)
> > +		return "R";
> > +	else if (in_vfork(p))
> > +		return "V";
> 
> This is going to be racy, we can't show that a task that is emitted as 
> part of the tasklist dump was did not have in_vfork() == true at the time 
> oom_badness() was called.

Yes, this is true.

> Wouldn't it be better to simply print the output of oom_badness() to the 
> tasklist dump instead so we get complete information?

I think this would be acceptable.

> We could simply special case a LONG_MIN return value as -1000 or "min".

Agreed.





Kind regards,

-- 
Aaron Tomlin