Re: [PATCH 1/2] pid_namespace: allow opening pid_for_children before init was created

[Oleg Nesterov]

On 02/22, Oleg Nesterov wrote:
>
> Pavel,
>
> Your patch doesn't apply to Linus's tree.
>
> and in any case... can you avoid read_lock(tasklist) in alloc_pid() ?
> This is really not good.

I'm afraid I am totally confused, but it looks unnecessary.

Once ->child_reaper is set, it can be changed but not cleared.
This means that pidns_for_children_get() doesn't need tasklist too.

However. With or without this patch, we probably need WRITE_ONCE()
in find_child_reaper() and copy_process() + READ_ONCE() in alloc_pid()
to avoid the possible warnings from KCSAN.

No?

Oleg.