Re: [PATCH 4/7] x86,tlb: make lazy TLB mode lazier

[Peter Zijlstra]

On Fri, Jul 20, 2018 at 11:32:39AM +0200, Peter Zijlstra wrote:

> +     if (!next->mm) {                                // to kernel
> +             enter_lazy_tlb(prev->active_mm, next);
> +
> +#ifdef ARCH_NO_ACTIVE_MM
> +             next->active_mm = prev->active_mm;
> +             if (prev->mm)                           // from user
> +                     mmgrab(prev->active_mm);
                else
                        prev->active_mm = NULL;
> +#endif
> +     } else {                                        // to user
> +             switch_mm_irqs_off(prev->active_mm, next->mm, next);
> +
> +#ifdef ARCH_NO_ACTIVE_MM
> +             if (!prev->mm) {                        // from kernel
> +                     /* will mmdrop() in finish_task_switch(). */
> +                     rq->prev_mm = prev->active_mm;
> +                     prev->active_mm = NULL;
> +             }
> +#endif
>       }