linux-kernel - [PATCH 3.16 143/410] drm/ttm: Don't add swapped BOs to swap-LRU list

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Message-ID: <lsq.1528380321.97250614@decadent.org.uk>
Date:   Thu, 07 Jun 2018 15:05:21 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Felix Kuehling" <Felix.Kuehling@....com>,
        "Christian König" <christian.koenig@....com>,
        "Alex Deucher" <alexander.deucher@....com>
Subject: [PATCH 3.16 143/410] drm/ttm: Don't add swapped BOs to swap-LRU list

3.16.57-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Felix Kuehling <Felix.Kuehling@....com>

commit fd5002d6a3c602664b07668a24df4ef7a43bf078 upstream.

A BO that's already swapped would be added back to the swap-LRU list
for example if its validation failed under high memory pressure. This
could later lead to swapping it out again and leaking previous swap
storage.

This commit adds a condition to prevent that from happening.

v2: Check page_flags instead of swap_storage

Signed-off-by: Felix Kuehling <Felix.Kuehling@....com>
Reviewed-by: Christian König <christian.koenig@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/gpu/drm/ttm/ttm_bo.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -175,7 +175,8 @@ void ttm_bo_add_to_lru(struct ttm_buffer
 		list_add_tail(&bo->lru, &man->lru);
 		kref_get(&bo->list_kref);
 
-		if (bo->ttm && !(bo->ttm->page_flags & TTM_PAGE_FLAG_SG)) {
+		if (bo->ttm && !(bo->ttm->page_flags &
+				 (TTM_PAGE_FLAG_SG | TTM_PAGE_FLAG_SWAPPED))) {
 			list_add_tail(&bo->swap, &bo->glob->swap_lru);
 			kref_get(&bo->list_kref);
 		}