Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH v4] mm: get rid of odd jump labels in
 find_mergeable_anon_vma()
To:     linmiaohe <linmiaohe@huawei.com>, akpm@linux-foundation.org,
        richardw.yang@linux.intel.com, sfr@canb.auug.org.au,
        rppt@linux.ibm.com, jannh@google.com, steve.capper@arm.com,
        catalin.marinas@arm.com, aarcange@redhat.com, walken@google.com,
        dave.hansen@linux.intel.com, tiny.windzz@gmail.com,
        jhubbard@nvidia.com
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org
References: <1574079844-17493-1-git-send-email-linmiaohe@huawei.com>
From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat GmbH
Message-ID: <6bc28c72-6a84-0579-da0c-59d4fd695682@redhat.com>
Date:   Mon, 18 Nov 2019 14:48:35 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.1.1
MIME-Version: 1.0
In-Reply-To: <1574079844-17493-1-git-send-email-linmiaohe@huawei.com>
Content-Language: en-US
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: quoted-printable
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 18.11.19 13:24, linmiaohe wrote:
> From: Miaohe Lin <linmiaohe@huawei.com>
>=20
> The jump labels try_prev and none are not really needed
> in find_mergeable_anon_vma(), eliminate them to improve
> readability.
>=20
> Reviewed-by: David Hildenbrand <david@redhat.com>
> Reviewed-by: John Hubbard <jhubbard@nvidia.com>
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---
> -v2:
> =09Fix commit descriptions and further simplify the code
> =09as suggested by David Hildenbrand and John Hubbard.
> -v3:
> =09Rewrite patch version info. Don't show this in commit log.
> -v4:
> =09Get rid of var near completely as well.
> ---
>   mm/mmap.c | 36 ++++++++++++++++--------------------
>   1 file changed, 16 insertions(+), 20 deletions(-)
>=20
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 91d5e097a4ed..4d93bda30eac 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -1273,26 +1273,22 @@ static struct anon_vma *reusable_anon_vma(struct =
vm_area_struct *old, struct vm_
>    */
>   struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
>   {
> -=09struct anon_vma *anon_vma;
> -=09struct vm_area_struct *near;
> -
> -=09near =3D vma->vm_next;
> -=09if (!near)
> -=09=09goto try_prev;
> -
> -=09anon_vma =3D reusable_anon_vma(near, vma, near);
> -=09if (anon_vma)
> -=09=09return anon_vma;
> -try_prev:
> -=09near =3D vma->vm_prev;
> -=09if (!near)
> -=09=09goto none;
> -
> -=09anon_vma =3D reusable_anon_vma(near, near, vma);
> -=09if (anon_vma)
> -=09=09return anon_vma;
> -none:
> +=09struct anon_vma *anon_vma =3D NULL;
> +
> +=09/* Try next first. */
> +=09if (vma->vm_next) {
> +=09=09anon_vma =3D reusable_anon_vma(vma->vm_next, vma, vma->vm_next);
> +=09=09if (anon_vma)
> +=09=09=09return anon_vma;
> +=09}
> +
> +=09/* Try prev next. */
> +=09if (vma->vm_prev)
> +=09=09anon_vma =3D reusable_anon_vma(vma->vm_prev, vma->vm_prev, vma);
> +
>   =09/*
> +=09 * We might reach here with anon_vma =3D=3D NULL if we can't find
> +=09 * any reusable anon_vma.
>   =09 * There's no absolute need to look only at touching neighbours:
>   =09 * we could search further afield for "compatible" anon_vmas.
>   =09 * But it would probably just be a waste of time searching,
> @@ -1300,7 +1296,7 @@ struct anon_vma *find_mergeable_anon_vma(struct vm_=
area_struct *vma)
>   =09 * We're trying to allow mprotect remerging later on,
>   =09 * not trying to minimize memory used for anon_vmas.
>   =09 */
> -=09return NULL;
> +=09return anon_vma;
>   }
>  =20
>   /*
>=20

Looks much better, thanks!

Reviewed-by: David Hildenbrand <david@redhat.com>

--=20

Thanks,

David / dhildenb