FAILED: patch "[PATCH] drm/amdgpu: set f_mapping on exported DMA-bufs" failed to apply to 4.14-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 4b277247b1df177a7a60f0601ebe3dc952e5dd54 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christian=20K=C3=B6nig?= <christian.koenig@amd.com>
Date: Mon, 13 Nov 2017 17:20:50 +0100
Subject: [PATCH] drm/amdgpu: set f_mapping on exported DMA-bufs
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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Otherwise we can't correctly CPU map TTM buffers.

Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
index 90af8e82b16a..ae9c106979d7 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
@@ -169,10 +169,14 @@ struct dma_buf *amdgpu_gem_prime_export(struct drm_device *dev,
 					int flags)
 {
 	struct amdgpu_bo *bo = gem_to_amdgpu_bo(gobj);
+	struct dma_buf *buf;
 
 	if (amdgpu_ttm_tt_get_usermm(bo->tbo.ttm) ||
 	    bo->flags & AMDGPU_GEM_CREATE_VM_ALWAYS_VALID)
 		return ERR_PTR(-EPERM);
 
-	return drm_gem_prime_export(dev, gobj, flags);
+	buf = drm_gem_prime_export(dev, gobj, flags);
+	if (!IS_ERR(buf))
+		buf->file->f_mapping = dev->anon_inode->i_mapping;
+	return buf;
 }