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Re: [PATCH -mm v2 1/3] mm/oom_kill: remove the wrong fatal_signal_pending() check in oom_kill_process()

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On 10/01, Michal Hocko wrote:
>
> On Wed 30-09-15 20:24:05, Oleg Nesterov wrote:
> [...]
> > It is possible that the group leader
> > has the pending SIGKILL because its sub-thread originated the coredump,
> > in this case we must not skip this process.
>
> I do not understand this. If the group leader has SIGKILL pending it
> will die anyway regardless whether we send another sigkill or not, no?

Yes it will die, but only after the coredump is finished.

Suppose we have a thread group with the group leader P and another
thread T. If T starts the coredump, it sends SIGKILL to P and waits
until it parks in exit_mm(). Then T actually dumps the core which may
need more memory, a lot of time, etc.

We need to kill this process. Yes, P is already killed and it sleeps
in TASK_UNINTERRUPTIBLE so this thread does not need SIGKILL. But
do_send_sig_info(P) will also find T and kill it too to make
dump_interrupted() == T.

Oleg.

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[PATCH -mm v2 1/3] mm/oom_kill: remove the wrong  fatal_signal_pending() check in oom_kill_process() Oleg Nesterov <oleg@redhat.com> - 2015-09-30 20:30 +0200
  Re: [PATCH -mm v2 1/3] mm/oom_kill: remove the wrong fatal_signal_pending()check in oom_kill_process() Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2015-10-01 13:00 +0200
  Re: [PATCH -mm v2 1/3] mm/oom_kill: remove the wrong  fatal_signal_pending() check in oom_kill_process() Michal Hocko <mhocko@kernel.org> - 2015-10-01 14:50 +0200
    Re: [PATCH -mm v2 1/3] mm/oom_kill: remove the wrong  fatal_signal_pending() check in oom_kill_process() Oleg Nesterov <oleg@redhat.com> - 2015-10-01 17:10 +0200
      Re: [PATCH -mm v2 1/3] mm/oom_kill: remove the wrong  fatal_signal_pending() check in oom_kill_process() Michal Hocko <mhocko@kernel.org> - 2015-10-01 17:30 +0200
        Re: [PATCH -mm v2 1/3] mm/oom_kill: remove the wrong  fatal_signal_pending() check in oom_kill_process() Oleg Nesterov <oleg@redhat.com> - 2015-10-01 17:50 +0200
          Re: [PATCH -mm v2 1/3] mm/oom_kill: remove the wrong  fatal_signal_pending() check in oom_kill_process() Michal Hocko <mhocko@kernel.org> - 2015-10-01 18:20 +0200
            Re: [PATCH -mm v2 1/3] mm/oom_kill: remove the wrong  fatal_signal_pending() check in oom_kill_process() Oleg Nesterov <oleg@redhat.com> - 2015-10-01 20:00 +0200
              Re: [PATCH -mm v2 1/3] mm/oom_kill: remove the wrong fatal_signal_pending() check in oom_kill_process() Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2015-10-02 13:40 +0200
                Re: [PATCH -mm v2 1/3] mm/oom_kill: remove the wrong  fatal_signal_pending() check in oom_kill_process() Michal Hocko <mhocko@kernel.org> - 2015-10-02 14:20 +0200
                Re: [PATCH -mm v2 1/3] mm/oom_kill: remove the wrong fatal_signal_pending() check in oom_kill_process() Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2015-10-02 14:40 +0200
                Re: [PATCH -mm v2 1/3] mm/oom_kill: remove the wrong  fatal_signal_pending() check in oom_kill_process() Michal Hocko <mhocko@kernel.org> - 2015-10-02 15:40 +0200
                Re: [PATCH -mm v2 1/3] mm/oom_kill: remove the wrong fatal_signal_pending() check in oom_kill_process() Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2015-10-02 16:10 +0200
                Re: [PATCH -mm v2 1/3] mm/oom_kill: remove the wrong  fatal_signal_pending() check in oom_kill_process() Oleg Nesterov <oleg@redhat.com> - 2015-10-02 16:20 +0200
                Re: [PATCH -mm v2 1/3] mm/oom_kill: remove the wrong  fatal_signal_pending() check in oom_kill_process() Oleg Nesterov <oleg@redhat.com> - 2015-10-02 16:10 +0200
                Re: [PATCH -mm v2 1/3] mm/oom_kill: remove the wrong  fatal_signal_pending() check in oom_kill_process() Michal Hocko <mhocko@kernel.org> - 2015-10-02 16:30 +0200
                Re: [PATCH -mm v2 1/3] mm/oom_kill: remove the wrong  fatal_signal_pending() check in oom_kill_process() Oleg Nesterov <oleg@redhat.com> - 2015-10-02 16:00 +0200
                Re: [PATCH -mm v2 1/3] mm/oom_kill: remove the wrong fatal_signal_pending() check in oom_kill_process() Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2015-10-02 16:40 +0200

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