[PATCH] drm/xe: Don't fail runtime suspend permanently on VRAM eviction -ENOMEM

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

If evicting VRAM to system memory fails with -ENOMEM during runtime
suspend to D3cold, the error is returned to the runtime PM core.
Runtime PM treats any error other than -EAGAIN or -EBUSY from the
->runtime_suspend() callback as fatal, records it in
dev->power.runtime_error, and refuses further runtime PM operations
on the device until the error is cleared.

Memory shortage is a transient condition, and with eviction now using
__GFP_RETRY_MAYFAIL it is also more likely to occur. Convert -ENOMEM
from the eviction to -EAGAIN so that the device stays active and
runtime suspend is retried at a later idle transition.

Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
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> # v6.8+
Assisted-by: LLM
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
---
 drivers/gpu/drm/xe/xe_pm.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xe/xe_pm.c b/drivers/gpu/drm/xe/xe_pm.c
index daa7ba2df317..9bf57ed1ea59 100644
--- a/drivers/gpu/drm/xe/xe_pm.c
+++ b/drivers/gpu/drm/xe/xe_pm.c
@@ -649,8 +649,16 @@ int xe_pm_runtime_suspend(struct xe_device *xe)
 
 	if (xe->d3cold.allowed) {
 		err = xe_bo_evict_all(xe);
-		if (err)
+		if (err) {
+			/*
+			 * Runtime PM treats errors other than -EAGAIN and
+			 * -EBUSY as fatal, so report memory shortage as
+			 * transient to allow a later retry.
+			 */
+			if (err == -ENOMEM)
+				err = -EAGAIN;
 			goto out_resume;
+		}
 	}
 
 	for_each_gt(gt, xe, id) {
-- 
2.56.0