Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20200615221607.7764-1-peterx@redhat.com> <20200615221607.7764-14-peterx@redhat.com>
In-Reply-To: <20200615221607.7764-14-peterx@redhat.com>
From:   Greentime Hu <green.hu@gmail.com>
Date:   Wed, 17 Jun 2020 09:05:18 +0800
Message-ID: <CAEbi=3e7t+=q5x3Wogr+EuejFxxmyuQTHE7jpDW++2n6MB2OWQ@mail.gmail.com>
Subject: Re: [PATCH 13/25] mm/nds32: Use mm_fault_accounting()
To:     Peter Xu <peterx@redhat.com>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Gerald Schaefer <gerald.schaefer@de.ibm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Nick Hu <nickhu@andestech.com>,
        Vincent Chen <deanbo422@gmail.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Peter Xu <peterx@redhat.com> =E6=96=BC 2020=E5=B9=B46=E6=9C=8816=E6=97=A5 =
=E9=80=B1=E4=BA=8C =E4=B8=8A=E5=8D=886:16=E5=AF=AB=E9=81=93=EF=BC=9A
>
> Use the new mm_fault_accounting() helper for page fault accounting.
>
> Avoid doing page fault accounting multiple times if the page fault is ret=
ried.
> Since at it, move the accounting after releasing mmap_sem.
>
> CC: Nick Hu <nickhu@andestech.com>
> CC: Greentime Hu <green.hu@gmail.com>
> CC: Vincent Chen <deanbo422@gmail.com>
> Signed-off-by: Peter Xu <peterx@redhat.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 a=
ddr,
>         struct mm_struct *mm;
>         struct vm_area_struct *vma;
>         int si_code;
> -       vm_fault_t fault;
> +       vm_fault_t fault, major =3D 0;
>         unsigned int mask =3D VM_ACCESS_FLAGS;
>         unsigned int flags =3D FAULT_FLAG_DEFAULT;
>
> @@ -208,6 +208,7 @@ void do_page_fault(unsigned long entry, unsigned long=
 addr,
>          */
>
>         fault =3D handle_mm_fault(vma, addr, flags);
> +       major |=3D 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 lon=
g 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 |=3D 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@gmail.com>