From: =?UTF-8?q?Christian=20K=C3=B6nig?= <christian.koenig@amd.com>
Date: Mon, 4 Dec 2017 11:17:54 +0100
Subject: drm/ttm: swap consecutive allocated cached pages v3
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Git-commit: 5ff7ec02f2f306d619c661ff8fd5392d3653d407
Patch-mainline: v4.15-rc3
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

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

v2: use swap
v3: check if it's really the first allocated page

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Roger He <Hongbo.He@amd.com>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/ttm/ttm_page_alloc.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/ttm/ttm_page_alloc.c
+++ b/drivers/gpu/drm/ttm/ttm_page_alloc.c
@@ -877,7 +877,7 @@ static int ttm_get_pages(struct page **p
 #endif
 	struct list_head plist;
 	struct page *p = NULL;
-	unsigned count;
+	unsigned count, first;
 	int r;
 
 	/* No pool for cached pages */
@@ -918,6 +918,7 @@ static int ttm_get_pages(struct page **p
 		}
 #endif
 
+		first = i;
 		while (npages) {
 			p = alloc_page(gfp_flags);
 			if (!p) {
@@ -925,6 +926,10 @@ static int ttm_get_pages(struct page **p
 				return -ENOMEM;
 			}
 
+			/* Swap the pages if we detect consecutive order */
+			if (i > first && pages[i - 1] == p - 1)
+				swap(p, pages[i - 1]);
+
 			pages[i++] = p;
 			--npages;
 		}