drm/gem: replace misleading comment

[deliverable/linux.git] / drivers / gpu / drm / drm_gem.c

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 9909bef5980045e3ba5eba0ec35187f4e2bbf0cf..f7d71190aad5c0c07495bd26e841b46dd959cd72 100644 (file)
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -474,21 +474,10 @@ struct page **drm_gem_get_pages(struct drm_gem_object *obj, gfp_t gfpmask)
                        goto fail;
                pages[i] = p;
 
-               /* There is a hypothetical issue w/ drivers that require
-                * buffer memory in the low 4GB.. if the pages are un-
-                * pinned, and swapped out, they can end up swapped back
-                * in above 4GB.  If pages are already in memory, then
-                * shmem_read_mapping_page_gfp will ignore the gfpmask,
-                * even if the already in-memory page disobeys the mask.
-                *
-                * It is only a theoretical issue today, because none of
-                * the devices with this limitation can be populated with
-                * enough memory to trigger the issue.  But this BUG_ON()
-                * is here as a reminder in case the problem with
-                * shmem_read_mapping_page_gfp() isn't solved by the time
-                * it does become a real issue.
-                *
-                * See this thread: http://lkml.org/lkml/2011/7/11/238
+               /* Make sure shmem keeps __GFP_DMA32 allocated pages in the
+                * correct region during swapin. Note that this requires
+                * __GFP_DMA32 to be set in mapping_gfp_mask(inode->i_mapping)
+                * so shmem can relocate pages during swapin if required.
                 */
                BUG_ON((gfpmask & __GFP_DMA32) &&
                                (page_to_pfn(p) >= 0x00100000UL));