This is a follup-up on the patch
sched: Delay task stack freeing on RT
https://lkml.kernel.org/r/20210928122411.593486363@xxxxxxxxxxxxx
It addresses the review feedback:
- Decouple stack accounting from its free invocation. The accounting
happens in do_exit(), the final free call happens later.
- Add put_task_stack_sched() to finish_task_switch(). Here the VMAP
stack is cached only. If it fails, or in the !VMAP case then the final
free happens in delayed_put_task_struct(). This is also an oportunity
to cache the stack.