[PATCH] drm/ttm: swap consecutive allocated pooled pages v4

[He, Roger]

Reviewed-by: Roger He <Hongbo.He at amd.com>

Thanks
Roger(Hongbo.He)
-----Original Message-----
From: Christian König [mailto:ckoenig.leichtzumerken at gmail.com] 
Sent: Tuesday, December 05, 2017 8:55 PM
To: dri-devel at lists.freedesktop.org; amd-gfx at lists.freedesktop.org; He, Roger <Hongbo.He at amd.com>
Subject: [PATCH] drm/ttm: swap consecutive allocated pooled pages v4

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
v4: don't touch the loop variable

Signed-off-by: Christian König <christian.koenig at amd.com>
---
 drivers/gpu/drm/ttm/ttm_page_alloc.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc.c b/drivers/gpu/drm/ttm/ttm_page_alloc.c
index b6f7ce286fb1..44343a2bf55c 100644
--- a/drivers/gpu/drm/ttm/ttm_page_alloc.c
+++ b/drivers/gpu/drm/ttm/ttm_page_alloc.c
@@ -958,8 +958,15 @@ static int ttm_get_pages(struct page **pages, unsigned npages, int flags,
 	r = ttm_page_pool_get_pages(pool, &plist, flags, cstate,
 				    npages - count, 0);
 
-	list_for_each_entry(p, &plist, lru)
-		pages[count++] = p;
+	first = count;
+	list_for_each_entry(p, &plist, lru) {
+		struct page *tmp = p;
+
+		/* Swap the pages if we detect consecutive order */
+		if (count > first && pages[count - 1] == tmp - 1)
+			swap(tmp, pages[count - 1]);
+		pages[count++] = tmp;
+	}
 
 	if (r) {
 		/* If there is any pages in the list put them back to
--
2.11.0