[PATCH v4 1/4] drm/xe: Don't abort the shrinker walk on -EBUSY

["Thomas Hellström" <thomas.hellstrom@linux.intel.com>]

xe_bo_shrink() returns -EBUSY for bos that can't currently be shrunk,
for example imported dma-bufs, bos whose vm is currently validating,
bos that are still busy after the wait timeout, or bos whose backup
fails. The shrinker LRU walk treats any negative return value as
fatal and aborts, which also skips the remaining shrinker passes.

As a result, a single such bo, like an imported dma-buf on the
XE_PL_TT LRU, prevents reclaim of all bos behind it on the LRU.

Skip bos for which xe_bo_shrink() returns -EBUSY and continue the
walk, like the TTM LRU walk does.

v4:
- Patch introduced.

Fixes: 00c8efc3180f ("drm/xe: Add a shrinker for xe bos")
Cc: Christian König <christian.koenig@amd.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: intel-xe@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v6.15+
Assisted-by: LLM
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
---
 drivers/gpu/drm/xe/xe_shrinker.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_shrinker.c b/drivers/gpu/drm/xe/xe_shrinker.c
index deb4378c1ec1..4e4da76936f4 100644
--- a/drivers/gpu/drm/xe/xe_shrinker.c
+++ b/drivers/gpu/drm/xe/xe_shrinker.c
@@ -113,6 +113,9 @@ static int __xe_shrinker_walk(struct xe_shrinker *shrinker,
 				continue;
 
 			lret = xe_bo_shrink(ctx, ttm_bo, flags, scanned);
+			/* Like the TTM LRU walk, skip bos we can't shrink now. */
+			if (lret == -EBUSY)
+				continue;
 			if (lret < 0) {
 				ret = lret;
 				goto out;
-- 
2.56.0