linux-kernel - Re: [PATCH v3 1/2] mm: use update_mmu

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Date:   Fri, 30 Sep 2022 16:43:07 +0800
From:   Qi Zheng <zhengqi.arch@...edance.com>
To:     David Hildenbrand <david@...hat.com>, akpm@...ux-foundation.org,
        maobibo@...ngson.cn, chenhuacai@...ngson.cn,
        songmuchun@...edance.com
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        loongarch@...ts.linux.dev, chris@...kel.net, jcmvbkbc@...il.com
Subject: Re: [PATCH v3 1/2] mm: use update_mmu_tlb() on the second thread



On 2022/9/30 16:30, David Hildenbrand wrote:
> On 29.09.22 13:23, Qi Zheng wrote:
>> As message in commit 7df676974359 ("mm/memory.c: Update local TLB
>> if PTE entry exists") said, we should update local TLB only on the
>> second thread. So in the do_anonymous_page() here, we should use
>> update_mmu_tlb() instead of update_mmu_cache() on the second thread.
>>
> 
> Maybe mention here "This only affects performance, but not correctness."

Oh, this is better. Hi Andrew, do I need to resend the v4?

> 
> Acked-by: David Hildenbrand <david@...hat.com>

Thanks.

> 
>> Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>
>> Reviewed-by: Muchun Song <songmuchun@...edance.com>
>> ---
>>   mm/memory.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/mm/memory.c b/mm/memory.c
>> index 118e5f023597..9e11c783ba0e 100644
>> --- a/mm/memory.c
>> +++ b/mm/memory.c
>> @@ -4122,7 +4122,7 @@ static vm_fault_t do_anonymous_page(struct 
>> vm_fault *vmf)
>>       vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
>>               &vmf->ptl);
>>       if (!pte_none(*vmf->pte)) {
>> -        update_mmu_cache(vma, vmf->address, vmf->pte);
>> +        update_mmu_tlb(vma, vmf->address, vmf->pte);
>>           goto release;
>>       }
> 

-- 
Thanks,
Qi