linux-kernel - Re: [PATCH v4 06/15] s390: pgtable: add statistics for PUD and P4D level page table

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Message-ID: <Z3uxVkg3i7zXI92e@li-008a6a4c-3549-11b2-a85c-c5cc2836eea2.ibm.com>
Date: Mon, 6 Jan 2025 11:32:54 +0100
From: Alexander Gordeev <agordeev@...ux.ibm.com>
To: Qi Zheng <zhengqi.arch@...edance.com>
Cc: peterz@...radead.org, kevin.brodsky@....com, palmer@...belt.com,
        tglx@...utronix.de, david@...hat.com, jannh@...gle.com,
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        npiggin@...il.com, dave.hansen@...ux.intel.com, rppt@...nel.org,
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        linux-arm-kernel@...ts.infradead.org, linuxppc-dev@...ts.ozlabs.org,
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Subject: Re: [PATCH v4 06/15] s390: pgtable: add statistics for PUD and P4D
 level page table

On Mon, Dec 30, 2024 at 05:07:41PM +0800, Qi Zheng wrote:
> Like PMD and PTE level page table, also add statistics for PUD and P4D
> page table.
...
> diff --git a/arch/s390/include/asm/tlb.h b/arch/s390/include/asm/tlb.h
> index e95b2c8081eb8..b946964afce8e 100644
> --- a/arch/s390/include/asm/tlb.h
> +++ b/arch/s390/include/asm/tlb.h
> @@ -110,24 +110,6 @@ static inline void pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd,
>  	tlb_remove_ptdesc(tlb, pmd);
>  }
>  
> -/*
> - * p4d_free_tlb frees a pud table and clears the CRSTE for the
> - * region second table entry from the tlb.
> - * If the mm uses a four level page table the single p4d is freed
> - * as the pgd. p4d_free_tlb checks the asce_limit against 8PB
> - * to avoid the double free of the p4d in this case.
> - */
> -static inline void p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d,
> -				unsigned long address)
> -{
> -	if (mm_p4d_folded(tlb->mm))
> -		return;
> -	__tlb_adjust_range(tlb, address, PAGE_SIZE);
> -	tlb->mm->context.flush_mm = 1;
> -	tlb->freed_tables = 1;
> -	tlb_remove_ptdesc(tlb, p4d);
> -}
> -
>  /*
>   * pud_free_tlb frees a pud table and clears the CRSTE for the
>   * region third table entry from the tlb.
> @@ -140,11 +122,30 @@ static inline void pud_free_tlb(struct mmu_gather *tlb, pud_t *pud,
>  {
>  	if (mm_pud_folded(tlb->mm))
>  		return;
> +	pagetable_pud_dtor(virt_to_ptdesc(pud));
>  	tlb->mm->context.flush_mm = 1;
>  	tlb->freed_tables = 1;
>  	tlb->cleared_p4ds = 1;
>  	tlb_remove_ptdesc(tlb, pud);
>  }
>  
> +/*
> + * p4d_free_tlb frees a p4d table and clears the CRSTE for the
> + * region second table entry from the tlb.
> + * If the mm uses a four level page table the single p4d is freed
> + * as the pgd. p4d_free_tlb checks the asce_limit against 8PB
> + * to avoid the double free of the p4d in this case.
> + */
> +static inline void p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d,
> +				unsigned long address)
> +{
> +	if (mm_p4d_folded(tlb->mm))
> +		return;
> +	pagetable_p4d_dtor(virt_to_ptdesc(p4d));
> +	__tlb_adjust_range(tlb, address, PAGE_SIZE);
> +	tlb->mm->context.flush_mm = 1;
> +	tlb->freed_tables = 1;
> +	tlb_remove_ptdesc(tlb, p4d);
> +}

I understand that you want to sort p.._free_tlb() routines, but please
do not move the code around or make a separate follow-up patch.

Thanks!