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Date: Wed, 12 Sep 2018 18:45:05 +0200
From: Oleg Nesterov <oleg@redhat.com>
Subject: Re: [PATCH] mm, oom: Introduce time limit for dump_tasks duration.
Message-ID: <20180912164505.GA18706@redhat.com>
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To: Michal Hocko <mhocko@kernel.org>
Cc: Dmitry Vyukov <dvyukov@google.com>, Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>, Andrew Morton <akpm@linux-foundation.org>, David Rientjes <rientjes@google.com>, syzbot <syzbot+f0fc7f62e88b1de99af3@syzkaller.appspotmail.com>, 'Dmitry Vyukov' via syzkaller-upstream-moderation <syzkaller-upstream-moderation@googlegroups.com>, linux-mm <linux-mm@kvack.org>

On 09/11, Oleg Nesterov wrote:
>
> On 09/06, Michal Hocko wrote:
> >
> > So a question for Oleg I guess. Is it possible that for_each_process
> > live locks (or stalls for way too long/unbounded amount of time) under
> > heavy fork/exit loads?
>
> Oh yes, it can... plus other problems.
>
> I even sent the initial patches which introduce for_each_process_break/continue
> a long ago... I'll try to find them tommorrow and resend.

Two years ago ;) I don't understand why there were ignored, please see
"[PATCH 0/2] introduce for_each_process_thread_break() and for_each_process_thread_continue()"
I sent a minute ago.

However, I didn't notice that the subject mentions oom/dump_tasks... As for
dump_tasks() it probably doesn't need the new helpers, I'll write another email
tomorrow, but perhaps the time limit is all we need.

Oleg.