Re: [to-be-updated] taskstats-copy-signal-stats-under-siglock-in-taskstats_exit.patch removed from -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

On Wed, 07 Oct 2026 18:19:50 +0100 Bradley Morgan <brads@mainlining.org> wrote:

> >
> >From 137b873cce7721384c9d24f4c0864bb002c8d039 Mon Sep 17 00:00:00 2001
> From: Bradley Morgan <include@grrlz.net>
> Date: Tue, 4 Aug 2026 09:34:00 +0000
> Subject: [PATCH v2] taskstats: copy signal->stats under siglock in
>  taskstats_exit

Thanks.  Please send as a standalone email and cc linux-kernel?  So we
get a nice Link: in the permanent record.  (mm-commits Links: work
though).

> --- a/kernel/taskstats.c
> +++ b/kernel/taskstats.c
> @@ -635,7 +635,10 @@ void taskstats_exit(struct task_struct *tsk, int group_dead)
>  	if (!stats)
>  		goto err;
>  
> +	/* This was racy before, copy the stats under siglock. */

That's not a great comment - we're really not interested in what is
essentially embedded changelogging.

A good comment would explain *why* we're taking the lock.  Briefly
describe what we're excluding against.

> +	spin_lock_irq(&tsk->sighand->siglock);
>  	memcpy(stats, tsk->signal->stats, sizeof(*stats));
> +	spin_unlock_irq(&tsk->sighand->siglock);
>  	stats->version = TASKSTATS_VERSION;