[PATCH 1/2] Avoid waking the device under the shrinker

[Janusz Krzysztofik]

From: Chris Wilson <chris.p.wilson at intel.com>

We cannot take intel_runtime_pm_get() from underneath fs_reclaim (as we
may hit fs_reclaim during runtime-resume), so we have to avoid unbind
from the shrinker while the device is asleep.

Testcase: igt/gem_mmap_offset/clear
Bug: https://gitlab.freedesktop.org/drm/intel/-/issues/6449
Cc: Matthew Auld <matthew.auld at intel.com>
Signed-off-by: Chris Wilson <chris.p.wilson at intel.com>
Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik at linux.intel.com>
---
 drivers/gpu/drm/i915/i915_gem.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 702e5b89be22..910a6fde5726 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -119,8 +119,8 @@ int i915_gem_object_unbind(struct drm_i915_gem_object *obj,
 {
 	struct intel_runtime_pm *rpm = &to_i915(obj->base.dev)->runtime_pm;
 	bool vm_trylock = !!(flags & I915_GEM_OBJECT_UNBIND_VM_TRYLOCK);
+	intel_wakeref_t wakeref = 0;
 	LIST_HEAD(still_in_list);
-	intel_wakeref_t wakeref;
 	struct i915_vma *vma;
 	int ret;
 
@@ -135,7 +135,8 @@ int i915_gem_object_unbind(struct drm_i915_gem_object *obj,
 	 * as they are required by the shrinker. Ergo, we wake the device up
 	 * first just in case.
 	 */
-	wakeref = intel_runtime_pm_get(rpm);
+	if (!(flags & I915_GEM_OBJECT_UNBIND_TEST))
+		wakeref = intel_runtime_pm_get(rpm);
 
 try_again:
 	ret = 0;
@@ -200,7 +201,8 @@ int i915_gem_object_unbind(struct drm_i915_gem_object *obj,
 		goto try_again;
 	}
 
-	intel_runtime_pm_put(rpm, wakeref);
+	if (wakeref)
+		intel_runtime_pm_put(rpm, wakeref);
 
 	return ret;
 }
-- 
2.25.1