Re: [PATCH 1/4] cpumask: Migrate 'alloc_cpumask_var()' users to 'zalloc_cpumask_var()'

[Linus Torvalds]

On Mon, Dec 7, 2015 at 12:49 AM, Ingo Molnar <mingo@xxxxxxxxxx> wrote:
> Xunlei Pang reported a scheduler bug in init_rootdomain(), which is
> caused by improper use of alloc_cpumask_var(), which results in
> uninitialized cpumasks being allocated.
>
> No-one noticed this scheduler bug for a long time, probably because
> alloc_cpumask_var() does result in initialized cpumasks in the
> !CPUMASK_OFFSTACK case - which is the vast majority of systems
> out there.
>
> So migrate all alloc_cpumask_var() users over to zalloc_cpumask_var(),
> to be on the safe side.

Ugh. I'd rather just see us say that "allocating a cpumask always
returns a zeroed mask".

There really is no reason to ever not zero it (they aren't _that_ big
even on huge machines), so I'd rather just get rid of the "zalloc"
version that is the less common one anyway.

                 Linus
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