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From:   Jason Gunthorpe <jgg@mellanox.com>
To:     Christoph Hellwig <hch@lst.de>
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        "amd-gfx@lists.freedesktop.org" <amd-gfx@lists.freedesktop.org>,
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Subject: Re: [PATCH 11/13] mm: cleanup the hmm_vma_handle_pmd stub
Thread-Topic: [PATCH 11/13] mm: cleanup the hmm_vma_handle_pmd stub
Thread-Index: AQHVRpsFqcopldMqYEmw+Nzxjc71m6bjchWA
Date:   Tue, 30 Jul 2019 17:53:14 +0000
Message-ID: <20190730175309.GN24038@mellanox.com>
References: <20190730055203.28467-1-hch@lst.de>
 <20190730055203.28467-12-hch@lst.de>
In-Reply-To: <20190730055203.28467-12-hch@lst.de>
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On Tue, Jul 30, 2019 at 08:52:01AM +0300, Christoph Hellwig wrote:
> Stub out the whole function when CONFIG_TRANSPARENT_HUGEPAGE is not set
> to make the function easier to read.
>=20
> Signed-off-by: Christoph Hellwig <hch@lst.de>
>  mm/hmm.c | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
>=20
> diff --git a/mm/hmm.c b/mm/hmm.c
> index 4d3bd41b6522..f4e90ea5779f 100644
> +++ b/mm/hmm.c
> @@ -455,13 +455,10 @@ static inline uint64_t pmd_to_hmm_pfn_flags(struct =
hmm_range *range, pmd_t pmd)
>  				range->flags[HMM_PFN_VALID];
>  }
> =20
> -static int hmm_vma_handle_pmd(struct mm_walk *walk,
> -			      unsigned long addr,
> -			      unsigned long end,
> -			      uint64_t *pfns,
> -			      pmd_t pmd)
> -{
>  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> +static int hmm_vma_handle_pmd(struct mm_walk *walk, unsigned long addr,
> +		unsigned long end, uint64_t *pfns, pmd_t pmd)
> +{
>  	struct hmm_vma_walk *hmm_vma_walk =3D walk->private;
>  	struct hmm_range *range =3D hmm_vma_walk->range;
>  	struct dev_pagemap *pgmap =3D NULL;
> @@ -490,11 +487,14 @@ static int hmm_vma_handle_pmd(struct mm_walk *walk,
>  		put_dev_pagemap(pgmap);
>  	hmm_vma_walk->last =3D end;
>  	return 0;
> -#else
> -	/* If THP is not enabled then we should never reach this=20

This old comment says we should never get here

> +}
> +#else /* CONFIG_TRANSPARENT_HUGEPAGE */
> +static int hmm_vma_handle_pmd(struct mm_walk *walk, unsigned long addr,
> +		unsigned long end, uint64_t *pfns, pmd_t pmd)
> +{
>  	return -EINVAL;

So could we just do
   #define hmm_vma_handle_pmd NULL

?

At the very least this seems like a WARN_ON too?

Jason