From: Michal Hocko <mhocko@kernel.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: linux-mm@kvack.org, David Rientjes <rientjes@google.com>,
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
Johannes Weiner <hannes@cmpxchg.org>,
Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: [PATCH 3/4] mm, oom: do not rely on TIF_MEMDIE for exit_oom_victim
Date: Wed, 5 Oct 2016 11:37:02 +0200 [thread overview]
Message-ID: <20161005093702.GB7138@dhcp22.suse.cz> (raw)
In-Reply-To: <20161004162114.GB32428@redhat.com>
On Tue 04-10-16 18:21:14, Oleg Nesterov wrote:
[...]
> so this can't detect the multi-threaded group exit, and ...
>
> > list_for_each_entry_safe(p, n, &dead, ptrace_entry) {
> > list_del_init(&p->ptrace_entry);
> > - release_task(p);
> > + if (release_task(p) && p == tsk)
> > + last = true;
>
> this can only happen if this process auto-reaps itself. Not to mention
> that exit_notify() will never return true if traced.
>
> No, this doesn't look right.
You are right. I should have noticed that. Especially when I was hunting
the strace hang bug. I started to have a bad feeling about this patch
but for some reason I just didn't put all the pieces together.
So the patch is completely b0rked. Back to drawing board and start
again. Oh well...
Anyway thanks and sorry to waste your time.
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2016-10-05 9:37 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-04 9:00 [PATCH 0/4] mm, oom: get rid of TIF_MEMDIE Michal Hocko
2016-10-04 9:00 ` [PATCH 1/4] mm, oom: do not rely on TIF_MEMDIE for memory reserves access Michal Hocko
2016-10-04 9:00 ` [PATCH 2/4] mm: replace TIF_MEMDIE checks by tsk_is_oom_victim Michal Hocko
2016-10-04 9:00 ` [PATCH 3/4] mm, oom: do not rely on TIF_MEMDIE for exit_oom_victim Michal Hocko
2016-10-04 16:21 ` Oleg Nesterov
2016-10-05 9:37 ` Michal Hocko [this message]
2016-10-04 9:00 ` [PATCH 4/4] arch: get rid of TIF_MEMDIE Michal Hocko
2016-10-05 12:04 ` [PATCH 0/4] mm, oom: " Michal Hocko
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