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References: <20201210004335.64634-1-pasha.tatashin@soleen.com> <20201210004335.64634-2-pasha.tatashin@soleen.com>
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From:   Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Date:   Thu, 10 Dec 2020 07:36:56 +0100
Message-ID: <CAM9Jb+g2B+uXH+Vj_FSMAh18j3DAKn4zKyAZNB_t8hSQ90a=mg@mail.gmail.com>
Subject: Re: [PATCH v2 1/8] mm/gup: perform check_dax_vmas only when FS_DAX is enabled
To:     Pavel Tatashin <pasha.tatashin@soleen.com>
Cc:     LKML <linux-kernel@vger.kernel.org>, Linux MM <linux-mm@kvack.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Michal Hocko <mhocko@suse.com>,
        David Hildenbrand <david@redhat.com>,
        Oscar Salvador <osalvador@suse.de>,
        Dan Williams <dan.j.williams@intel.com>, sashal@kernel.org,
        tyhicks@linux.microsoft.com, Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        mike.kravetz@oracle.com, rostedt@goodmis.org,
        Ingo Molnar <mingo@redhat.com>,
        "Dave Jiang <dave.jiang@intel.com>, Jason Gunthorpe <jgg@ziepe.ca>,
        Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>, Johannes Thumshirn
        <jthumshirn@suse.de>, Logan Gunthorpe" <jgg@ziepe.ca>,
        Peter Zijlstra <peterz@infradead.org>,
        Mel Gorman <mgorman@suse.de>,
        Matthew Wilcox <willy@infradead.org>,
        David Rientjes <rientjes@google.com>,
        John Hubbard <jhubbard@nvidia.com>, linux-doc@vger.kernel.org
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> There is no need to check_dax_vmas() and run through the npage loop of
> pinned pages if FS_DAX is not enabled.
>
> Add a stub check_dax_vmas() function for no-FS_DAX case.
>
> Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
> Reviewed-by: John Hubbard <jhubbard@nvidia.com>
> ---
>  mm/gup.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/mm/gup.c b/mm/gup.c
> index 98eb8e6d2609..cdb8b9eeb016 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -1568,6 +1568,7 @@ struct page *get_dump_page(unsigned long addr)
>  #endif /* CONFIG_ELF_CORE */
>
>  #if defined(CONFIG_FS_DAX) || defined (CONFIG_CMA)
> +#ifdef CONFIG_FS_DAX
>  static bool check_dax_vmas(struct vm_area_struct **vmas, long nr_pages)
>  {
>         long i;
> @@ -1586,6 +1587,12 @@ static bool check_dax_vmas(struct vm_area_struct **vmas, long nr_pages)
>         }
>         return false;
>  }
> +#else
> +static bool check_dax_vmas(struct vm_area_struct **vmas, long nr_pages)
> +{
> +       return false;
> +}
> +#endif
>
>  #ifdef CONFIG_CMA
>  static long check_and_migrate_cma_pages(struct mm_struct *mm,

Reviewed-by: Pankaj Gupta <pankaj.gupta@cloud.ionos.com>