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Subject: Re: [PATCH] mm/migrate: initialize pud_entry in migrate_vma()
To:     Ralph Campbell <rcampbell@nvidia.com>, <linux-mm@kvack.org>
CC:     <linux-kernel@vger.kernel.org>, <stable@vger.kernel.org>,
        =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= <jglisse@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>
References: <20190719233225.12243-1-rcampbell@nvidia.com>
From:   John Hubbard <jhubbard@nvidia.com>
Message-ID: <de0f0abd-d521-9b68-80b2-92e06c6bb8ac@nvidia.com>
Date:   Fri, 19 Jul 2019 19:03:54 -0700
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On 7/19/19 4:32 PM, Ralph Campbell wrote:
> When CONFIG_MIGRATE_VMA_HELPER is enabled, migrate_vma() calls
> migrate_vma_collect() which initializes a struct mm_walk but
> didn't initialize mm_walk.pud_entry. (Found by code inspection)
> Use a C structure initialization to make sure it is set to NULL.
>=20
> Fixes: 8763cb45ab967 ("mm/migrate: new memory migration helper for use wi=
th
> device memory")
> Cc: stable@vger.kernel.org
> Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
> Cc: "J=C3=A9r=C3=B4me Glisse" <jglisse@redhat.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> ---
>  mm/migrate.c | 17 +++++++----------
>  1 file changed, 7 insertions(+), 10 deletions(-)
>=20
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 515718392b24..a42858d8e00b 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -2340,16 +2340,13 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
>  static void migrate_vma_collect(struct migrate_vma *migrate)
>  {
>  	struct mmu_notifier_range range;
> -	struct mm_walk mm_walk;
> -
> -	mm_walk.pmd_entry =3D migrate_vma_collect_pmd;
> -	mm_walk.pte_entry =3D NULL;
> -	mm_walk.pte_hole =3D migrate_vma_collect_hole;
> -	mm_walk.hugetlb_entry =3D NULL;
> -	mm_walk.test_walk =3D NULL;
> -	mm_walk.vma =3D migrate->vma;
> -	mm_walk.mm =3D migrate->vma->vm_mm;
> -	mm_walk.private =3D migrate;
> +	struct mm_walk mm_walk =3D {
> +		.pmd_entry =3D migrate_vma_collect_pmd,
> +		.pte_hole =3D migrate_vma_collect_hole,
> +		.vma =3D migrate->vma,
> +		.mm =3D migrate->vma->vm_mm,
> +		.private =3D migrate,
> +	};

Neatly done.

> =20
>  	mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, NULL, mm_walk.mm,
>  				migrate->start,
>=20

Reviewed-by: John Hubbard <jhubbard@nvidia.com>

thanks,
--=20
John Hubbard
NVIDIA