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Date:   Thu, 8 Oct 2020 12:39:37 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     Christian =?iso-8859-1?Q?K=F6nig?= 
        <ckoenig.leichtzumerken@gmail.com>
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        linaro-mm-sig@lists.linaro.org, dri-devel@lists.freedesktop.org,
        linux-media@vger.kernel.org, chris@chris-wilson.co.uk,
        airlied@redhat.com, akpm@linux-foundation.org, daniel@ffwll.ch,
        sumit.semwal@linaro.org
Subject: Re: [PATCH 1/4] mm: introduce vma_set_file function v2
Message-ID: <20201008113937.GB20115@casper.infradead.org>
References: <20201008112342.9394-1-christian.koenig@amd.com>
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In-Reply-To: <20201008112342.9394-1-christian.koenig@amd.com>
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On Thu, Oct 08, 2020 at 01:23:39PM +0200, Christian K?nig wrote:
>  drivers/dma-buf/dma-buf.c                  | 16 +++++-----------
>  drivers/gpu/drm/etnaviv/etnaviv_gem.c      |  4 +---
>  drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c |  3 +--
>  drivers/gpu/drm/i915/gem/i915_gem_mman.c   |  4 ++--
>  drivers/gpu/drm/msm/msm_gem.c              |  4 +---
>  drivers/gpu/drm/omapdrm/omap_gem.c         |  3 +--
>  drivers/gpu/drm/vgem/vgem_drv.c            |  3 +--
>  drivers/staging/android/ashmem.c           |  5 ++---
...
> +++ b/mm/mmap.c
> @@ -136,6 +136,22 @@ void vma_set_page_prot(struct vm_area_struct *vma)
>  	WRITE_ONCE(vma->vm_page_prot, vm_page_prot);
>  }
>  
> +/*
> + * Change backing file, only valid to use during initial VMA setup.
> + */
> +struct file *vma_set_file(struct vm_area_struct *vma, struct file *file)
> +{
> +	if (file)
> +	        get_file(file);
> +
> +	swap(vma->vm_file, file);
> +
> +	if (file)
> +		fput(file);
> +
> +	return file;
> +}
> +

These users are all potentially modules.  You need an EXPORT_SYMBOL()?