linux-kernel - Re: [PATCH 13/25] mm/nds32: Use mm_fault

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Message-ID: <CAEbi=3e7t+=q5x3Wogr+EuejFxxmyuQTHE7jpDW++2n6MB2OWQ@mail.gmail.com>
Date:   Wed, 17 Jun 2020 09:05:18 +0800
From:   Greentime Hu <green.hu@...il.com>
To:     Peter Xu <peterx@...hat.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Gerald Schaefer <gerald.schaefer@...ibm.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Nick Hu <nickhu@...estech.com>,
        Vincent Chen <deanbo422@...il.com>
Subject: Re: [PATCH 13/25] mm/nds32: Use mm_fault_accounting()

Peter Xu <peterx@...hat.com> 於 2020年6月16日 週二 上午6:16寫道：
>
> Use the new mm_fault_accounting() helper for page fault accounting.
>
> Avoid doing page fault accounting multiple times if the page fault is retried.
> Since at it, move the accounting after releasing mmap_sem.
>
> CC: Nick Hu <nickhu@...estech.com>
> CC: Greentime Hu <green.hu@...il.com>
> CC: Vincent Chen <deanbo422@...il.com>
> Signed-off-by: Peter Xu <peterx@...hat.com>
> ---
>  arch/nds32/mm/fault.c | 19 +++----------------
>  1 file changed, 3 insertions(+), 16 deletions(-)
>
> diff --git a/arch/nds32/mm/fault.c b/arch/nds32/mm/fault.c
> index f331e533edc2..11537c03ab1d 100644
> --- a/arch/nds32/mm/fault.c
> +++ b/arch/nds32/mm/fault.c
> @@ -78,7 +78,7 @@ void do_page_fault(unsigned long entry, unsigned long addr,
>         struct mm_struct *mm;
>         struct vm_area_struct *vma;
>         int si_code;
> -       vm_fault_t fault;
> +       vm_fault_t fault, major = 0;
>         unsigned int mask = VM_ACCESS_FLAGS;
>         unsigned int flags = FAULT_FLAG_DEFAULT;
>
> @@ -208,6 +208,7 @@ void do_page_fault(unsigned long entry, unsigned long addr,
>          */
>
>         fault = handle_mm_fault(vma, addr, flags);
> +       major |= fault & VM_FAULT_MAJOR;
>
>         /*
>          * If we need to retry but a fatal signal is pending, handle the
> @@ -229,22 +230,7 @@ void do_page_fault(unsigned long entry, unsigned long addr,
>                         goto bad_area;
>         }
>
> -       /*
> -        * Major/minor page fault accounting is only done on the initial
> -        * attempt. If we go through a retry, it is extremely likely that the
> -        * page will be found in page cache at that point.
> -        */
> -       perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
>         if (flags & FAULT_FLAG_ALLOW_RETRY) {
> -               if (fault & VM_FAULT_MAJOR) {
> -                       tsk->maj_flt++;
> -                       perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ,
> -                                     1, regs, addr);
> -               } else {
> -                       tsk->min_flt++;
> -                       perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN,
> -                                     1, regs, addr);
> -               }
>                 if (fault & VM_FAULT_RETRY) {
>                         flags |= FAULT_FLAG_TRIED;
>
> @@ -257,6 +243,7 @@ void do_page_fault(unsigned long entry, unsigned long addr,
>         }
>
>         up_read(&mm->mmap_sem);
> +       mm_fault_accounting(tsk, regs, addr, major);
>         return;
>
>         /*
> --
Hi Peter,

Thank you. :)
Acked-by: Greentime Hu <green.hu@...il.com>