[PATCH 1/2] drm/ttm: swap consecutive allocated cached pages

Christian König ckoenig.leichtzumerken at gmail.com
Mon Dec 4 11:42:23 UTC 2017


When we detect consecutive allocation of pages swap them to avoid
accidentally freeing them as huge page.

Signed-off-by: Christian König <christian.koenig at amd.com>
---
 drivers/gpu/drm/ttm/ttm_page_alloc.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc.c b/drivers/gpu/drm/ttm/ttm_page_alloc.c
index c82d94cbbabc..60401350a01a 100644
--- a/drivers/gpu/drm/ttm/ttm_page_alloc.c
+++ b/drivers/gpu/drm/ttm/ttm_page_alloc.c
@@ -921,6 +921,14 @@ static int ttm_get_pages(struct page **pages, unsigned npages, int flags,
 				return -ENOMEM;
 			}
 
+			/* Swap the pages if we detect consecutive order */
+			if (i && pages[i - 1] == p - 1) {
+				struct page *tmp = p;
+
+				p = pages[i - 1];
+				pages[i - 1] = tmp;
+			}
+
 			pages[i++] = p;
 			--npages;
 		}
-- 
2.11.0



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