Re: [PATCH 09/10] kthread: Ensure struct kthread is present for all kthreads

[Linus Torvalds]

On Wed, Dec 22, 2021 at 3:25 PM Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote:
>
> Solve this by skipping the put_user for all kthreads.

Ugh.

While this fixes the problem, could we please just not mis-use that
'set_child_tid' as that kthread pointer any more?

It was always kind of hacky. I think a new pointer with the proper
'struct kthread *' type would be an improvement.

One of the "arguments" in the comment for re-using that set_child_tid
pointer was that 'fork()' used to not wrongly copy it, but your patch
literally now does that "allocate new kthread struct" at fork-time, so
that argument is actually bogus now.

              Linus