linux-kernel - Re: [RFC PATCH 1/8] signal: Dequeue SIGKILL even if SIGNAL_GROUP_EXIT/group_exec

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Message-ID: <20230522133038.GB22159@redhat.com>
Date:   Mon, 22 May 2023 15:30:39 +0200
From:   Oleg Nesterov <oleg@...hat.com>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Mike Christie <michael.christie@...cle.com>, linux@...mhuis.info,
        nicolas.dichtel@...nd.com, axboe@...nel.dk,
        torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, mst@...hat.com,
        sgarzare@...hat.com, jasowang@...hat.com, stefanha@...hat.com,
        brauner@...nel.org
Subject: Re: [RFC PATCH 1/8] signal: Dequeue SIGKILL even if
 SIGNAL_GROUP_EXIT/group_exec_task is set

On 05/18, Eric W. Biederman wrote:
>
>  void recalc_sigpending(void)
>  {
> -       if (!recalc_sigpending_tsk(current) && !freezing(current))
> +       if ((!recalc_sigpending_tsk(current) && !freezing(current)) ||
> +           ((current->signal->flags & SIGNAL_GROUP_EXIT) &&
> +                   !__fatal_signal_pending(current)))
>                 clear_thread_flag(TIF_SIGPENDING);
>  
>  }
> @@ -1043,6 +1045,13 @@ static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
>                  * This signal will be fatal to the whole group.
>                  */
>                 if (!sig_kernel_coredump(sig)) {
> +                       /*
> +                        * The signal is being short circuit delivered
> +                        * don't it pending.
> +                        */
> +                       if (type != PIDTYPE_PID) {
> +                               sigdelset(&t->signal->shared_pending,  sig);
> +
>                         /*
>                          * Start a group exit and wake everybody up.
>                          * This way we don't have other threads

Eric, sorry. I fail to understand this patch.

How can it help? And whom?

Perhaps we can discuss it in the context of the new series from Mike?

Oleg.