linux-kernel - Re: [PATCH] proc, oom: do not report alien mms when setting oom_score

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Message-Id: <201902150057.x1F0vxHb076966@www262.sakura.ne.jp>
Date:   Fri, 15 Feb 2019 09:57:59 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        David Rientjes <rientjes@...gle.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Yong-Taek Lee <ytk.lee@...sung.com>, linux-mm@...ck.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] proc, oom: do not report alien mms when setting
 oom_score_adj

Sigh, you are again misunderstanding...

I'm not opposing to forbid CLONE_VM without CLONE_SIGHAND threading model.
I'm asserting that we had better revert the iteration for now, even if we will
strive towards forbidding CLONE_VM without CLONE_SIGHAND threading model.

You say "And that is a correctness issue." but your patch is broken because
your patch does not close the race. Since nobody seems to be using CLONE_VM
without CLONE_SIGHAND threading, we can both avoid hungtask problem and close
the race by eliminating this broken iteration. We don't need to worry about
"This could easily lead to breaking the OOM_SCORE_ADJ_MIN protection." case
because setting OOM_SCORE_ADJ_MIN needs administrator's privilege. And it is
YOUR PATCH that still allows leading to breaking the OOM_SCORE_ADJ_MIN
protection. My patch is more simpler and accurate than your patch.