[PATCH 4/4] drm/i915/gem: Taint all shrinkable object locks

[Chris Wilson]

From: Chris Wilson <ickle at kabylake.alporthouse.com>

If we declare that an object type is shrinkable (any that we can reclaim
to recover system pages), make sure we taint the object mutex so that
lockdep expects us to use it within fs_reclaim. lockdep will then
complain the first time we try to allocate while holding the plain
mutex, as doing so invites potential recursion.

Signed-off-by: Chris Wilson <ickle at kabylake.alporthouse.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_object.c | 4 ++++
 drivers/gpu/drm/i915/intel_memory_region.h | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.c b/drivers/gpu/drm/i915/gem/i915_gem_object.c
index 99356c00c19e..21635dd415a3 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.c
@@ -72,6 +72,10 @@ void i915_gem_object_init(struct drm_i915_gem_object *obj,
 	obj->mm.madv = I915_MADV_WILLNEED;
 	INIT_RADIX_TREE(&obj->mm.get_page.radix, GFP_KERNEL | __GFP_NOWARN);
 	mutex_init(&obj->mm.get_page.lock);
+
+	if (IS_ENABLED(CONFIG_LOCKDEP) && i915_gem_object_is_shrinkable(obj))
+		i915_gem_shrinker_taints_mutex(to_i915(obj->base.dev),
+					       &obj->mm.lock);
 }
 
 /**
diff --git a/drivers/gpu/drm/i915/intel_memory_region.h b/drivers/gpu/drm/i915/intel_memory_region.h
index 232490d89a83..04fb5e6e8172 100644
--- a/drivers/gpu/drm/i915/intel_memory_region.h
+++ b/drivers/gpu/drm/i915/intel_memory_region.h
@@ -59,6 +59,8 @@ extern const u32 intel_region_map[];
 struct intel_memory_region_ops {
 	unsigned int flags;
 
+	struct lock_class_key lock_class;
+
 	int (*init)(struct intel_memory_region *mem);
 	void (*release)(struct intel_memory_region *mem);
 
-- 
2.20.1