[PATCH] drm/ttm: apply the swapout bulk_move fix to the intended condition

[Vadim Nikitushkin]

Commit 3db7d7d58341 ("drm/ttm: fix swapped-out resources never leaving
their bulk_move range") landed in drm-misc-fixes with its one-line
change applied to the wrong "if": the "if (ret)" after
ttm_resource_try_charge() in ttm_bo_alloc_at_place() became
"if (ret > 0)", while the "if (!ret)" after ttm_tt_swapout() in
ttm_bo_swapout_cb() that the patch targeted was left untouched.

ttm_resource_try_charge() returns 0 or a negative error code, so with
"ret > 0" a failed dmem cgroup charge no longer fails the allocation.
Restore that check and apply the intended change: ttm_tt_swapout()
returns the number of pages swapped out on success, so the bulk_move
removal must run for ret > 0.

Fixes: 3db7d7d58341 ("drm/ttm: fix swapped-out resources never leaving their bulk_move range")
Cc: stable@xxxxxxxxxxxxxxx # v7.1+
Signed-off-by: Vadim Nikitushkin <bub4z0r@xxxxxxxxx>
---
Christian, the commit in drm-misc-fixes (3db7d7d58341) ended up with the
change applied to the try_charge condition at line 532 instead of the
swapout one at line 1434; the resulting tree still has "if (!ret)" in
ttm_bo_swapout_cb(). This is a fix-up on top of 3db7d7d58341 since
drm-misc-fixes does not rebase. Sorry for the noise.

 drivers/gpu/drm/ttm/ttm_bo.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index a12af5b..9b85b5f 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -532,7 +532,7 @@ static int ttm_bo_alloc_at_place(struct ttm_buffer_object *bo,
 		ret = ttm_resource_try_charge(bo, place, &alloc_state->charge_pool,
 					      force_space ? &alloc_state->limit_pool
 							  : NULL);
-		if (ret > 0) {
+		if (ret) {
 			/*
 			 * -EAGAIN means the charge failed, which we treat
 			 * like an allocation failure. Therefore, return an
@@ -1434,7 +1434,7 @@ ttm_bo_swapout_cb(struct ttm_lru_walk *walk, struct ttm_buffer_object *bo)
 
 	if (ttm_tt_is_populated(tt)) {
 		ret = ttm_tt_swapout(bdev, tt, swapout_walk->gfp_flags);
-		if (!ret) {
+		if (ret > 0) {
 			spin_lock(&bdev->lru_lock);
 			ttm_resource_del_bulk_move_unevictable(bo->resource, bo);
 			ttm_resource_move_to_lru_tail(bo->resource);
-- 
2.53.0