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

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Message-ID: <a3a2bd64-9952-4c66-8626-f2436ce07d1d@bytedance.com>
Date: Mon, 6 Jan 2025 19:05:16 +0800
From: Qi Zheng <zhengqi.arch@...edance.com>
To: Alexander Gordeev <agordeev@...ux.ibm.com>
Cc: peterz@...radead.org, kevin.brodsky@....com, palmer@...belt.com,
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 rppt@...nel.org, ryan.roberts@....com, linux-mm@...ck.org,
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Subject: Re: [PATCH v4 06/15] s390: pgtable: add statistics for PUD and P4D
 level page table



On 2025/1/6 18:32, Alexander Gordeev wrote:
> 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

Yes, I thought it was a minor change, so I just did it.

> do not move the code around or make a separate follow-up patch.

Well, if you have a strong opinion about this, I can send an updated
patch.

Thanks!

> 
> Thanks!