Re: [PATCH 5/7] powerpc/mm: support nested lazy_mmu sections

[Alexander Gordeev]

On Thu, Sep 04, 2025 at 01:57:34PM +0100, Kevin Brodsky wrote:
...
>  static inline lazy_mmu_state_t arch_enter_lazy_mmu_mode(void)
>  {
>  	struct ppc64_tlb_batch *batch;
> +	int lazy_mmu_nested;
>  
>  	if (radix_enabled())
>  		return LAZY_MMU_DEFAULT;
> @@ -39,9 +40,14 @@ static inline lazy_mmu_state_t arch_enter_lazy_mmu_mode(void)
>  	 */
>  	preempt_disable();
>  	batch = this_cpu_ptr(&ppc64_tlb_batch);
> -	batch->active = 1;
> +	lazy_mmu_nested = batch->active;
>  
> -	return LAZY_MMU_DEFAULT;
> +	if (!lazy_mmu_nested) {

Why not just?

	if (!batch->active) {

> +		batch->active = 1;
> +		return LAZY_MMU_DEFAULT;
> +	} else {
> +		return LAZY_MMU_NESTED;
> +	}
>  }
>  
>  static inline void arch_leave_lazy_mmu_mode(lazy_mmu_state_t state)
> @@ -54,7 +60,10 @@ static inline void arch_leave_lazy_mmu_mode(lazy_mmu_state_t state)
>  
>  	if (batch->index)
>  		__flush_tlb_pending(batch);
> -	batch->active = 0;
> +
> +	if (state != LAZY_MMU_NESTED)
> +		batch->active = 0;
> +
>  	preempt_enable();
>  }

Thanks!