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SubjectRe: [PATCH v3 1/2] mm: use update_mmu_tlb() on the second thread
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On 2022/10/1 06:31, Andrew Morton wrote:
> On Fri, 30 Sep 2022 10:44:21 +0200 David Hildenbrand <david@redhat.com> wrote:
>
>>> Oh, this is better. Hi Andrew, do I need to resend the v4?
>>>
>>
>> I assume he can squash it, most probably no need to resend. :)
>
>
> From: Qi Zheng <zhengqi.arch@bytedance.com>
> Subject: mm: use update_mmu_tlb() on the second thread
> Date: Thu, 29 Sep 2022 19:23:17 +0800
>
> 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.
>
> As David pointed out, this is a performance improvement, not a
> correctness fix.
>
> Link: https://lkml.kernel.org/r/20220929112318.32393-2-zhengqi.arch@bytedance.com
> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
> Reviewed-by: Muchun Song <songmuchun@bytedance.com>
> Acked-by: David Hildenbrand <david@redhat.com>
> Cc: Bibo Mao <maobibo@loongson.cn>
> Cc: Chris Zankel <chris@zankel.net>
> Cc: Huacai Chen <chenhuacai@loongson.cn>
> Cc: Max Filippov <jcmvbkbc@gmail.com>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
>
> mm/memory.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- a/mm/memory.c~mm-use-update_mmu_tlb-on-the-second-thread
> +++ a/mm/memory.c
> @@ -4136,7 +4136,7 @@ static vm_fault_t do_anonymous_page(stru
> 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;
> }
>
> _

Thank you very much! :)

>

--
Thanks,
Qi

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