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| author | David Herrmann <dh.herrmann@gmail.com> | 2014-05-25 14:34:08 +0200 |
|---|---|---|
| committer | Dave Airlie <airlied@redhat.com> | 2014-05-27 15:50:57 +1000 |
| commit | 2123000b01792e182fc4122fdb612ed641f3385e (patch) | |
| tree | 6c3ec1eb99982fee7f44d95654d7867db04898a3 | |
| parent | 89086bca67f04a538765faf39ea7c1b718beaf34 (diff) | |
| download | linux-2123000b01792e182fc4122fdb612ed641f3385e.tar.bz2 | |
drm/gem: replace misleading comment
shmem supports page-relocations during swapin since quite some time. It
was implemented in:
commit bde05d1ccd512696b09db9dd2e5f33ad19152605
Author: Hugh Dickins <hughd@google.com>
Date: Tue May 29 15:06:38 2012 -0700
shmem: replace page if mapping excludes its zone
The gem-comment about wrongly placed DMA32 pages is no longer valid.
Replace it with a proper comment but keep the BUG_ON() to verify correct
shmem behavior.
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>
| -rw-r--r-- | drivers/gpu/drm/drm_gem.c | 19 |
1 files changed, 4 insertions, 15 deletions
diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c index 9909bef59800..f7d71190aad5 100644 --- 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)); |