Re: [PATCH 0/1] kthreads: simplify !kthreadd_task logic, killkthreadd_task_init_done

[Oleg Nesterov]

On 09/18, Linus Torvalds wrote:
>
> As to why pid == 0 wouldn't work, I don't know, but I'll take your word
> for it.

Say, admin wants to renice kthreadd or change its affinity. And we can't
show kthread in /proc if its pid is 0.

This can be changed afaics, we can even remove pidmap_init()->set_bit(0) so
that the first copy_process()->alloc_pid() will create the pid with nr == 0.
We don't care about unhashed init_struct_pid which also has nr == 0.

But I don't think this would be good, currently the code can safely assume
that the valid pid can't be 0. For example, find_process_by_pid(0) returns
current.

Oleg.

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