linux-kernel - Re: [PATCH] random: Fix crashes with sparse node ids

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Date:	Sat, 30 Jul 2016 13:27:00 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Michael Ellerman <mpe@...erman.id.au>
Cc:	"Theodore Ts'o" <tytso@....edu>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linuxppc-dev list <linuxppc-dev@...abs.org>
Subject: Re: [PATCH] random: Fix crashes with sparse node ids

On Sat, Jul 30, 2016 at 7:23 AM, Michael Ellerman <mpe@...erman.id.au> wrote:
>  #ifdef CONFIG_NUMA
> -       pool = kmalloc(num_nodes * sizeof(void *),
> +       pool = kmalloc(nr_node_ids * sizeof(void *),
>                        GFP_KERNEL|__GFP_NOFAIL|__GFP_ZERO);
>         for_each_online_node(i) {
>                 crng = kmalloc_node(sizeof(struct crng_state),

Ugh. Can we please also just change that kmalloc to kcalloc()? Get rid
of the odd multiplication and the unusual GFP mask bit crud?

And instead of using "sizeof(void *)", just use the pool entry size,
ie "sizeof(*pool)". Yes, we have other places where we depend on void
pointers having the same size as others, but it's the RightThing(tm)
to do anyway, and it makes more sense when you grep things ("Oh, we're
allocating 'nr_node_id' copes of *pool entries" even without knowing
what type is behind the "pool" pointer).

IOW, can you confirm that you could just use

        pool = kcalloc(nr_node_ids, sizeof(*pool), GFP_KERNEL);

instead? I'd much rather apply that patch.

               Linus