Re: [PATCH v3 00/13] Virtually mapped stacks with guard pages (x86, core)

[Linus Torvalds]

On Sat, Jun 25, 2016 at 4:30 PM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
>
> Maybe I'm misunderstanding the role of release_task.  It looks like
> there's this path in the scheduler I can borrow:
>
>     if (unlikely(prev_state == TASK_DEAD)) {
>
> With a kludge in place to free the stack in there and release_task and
> __put_task_struct, whichever is first, I get a nice speedup.
> Benchmarks coming later on.  Can I rely on that code path always being
> called?

Absolutely. That's the normal "task is done, put the thread struct".
IOW, that's the final "put_task_struct()" that the task "itself" calls
as it exits - there may be other things that hold a reference to the
task struct, but that's where you should free the stack because the
thread itself is done with it..

            Linus