[PATCH 24/29] vm-mutex

[Chris Wilson]

---
 drivers/gpu/drm/i915/i915_gem_gtt.c | 16 ++++++++++++++++
 drivers/gpu/drm/i915/i915_gem_gtt.h |  2 ++
 2 files changed, 18 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index d0a55e8853b5..07c5af85c127 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -28,6 +28,7 @@
 #include <linux/fault-inject.h>
 #include <linux/log2.h>
 #include <linux/random.h>
+#include <linux/sched/mm.h>
 #include <linux/seq_file.h>
 #include <linux/stop_machine.h>
 
@@ -2107,6 +2108,7 @@ static void i915_address_space_init(struct i915_address_space *vm,
 				    struct drm_i915_private *dev_priv,
 				    const char *name)
 {
+	mutex_init(&vm->mutex);
 	drm_mm_init(&vm->mm, 0, vm->total);
 	vm->mm.head_node.color = I915_COLOR_UNEVICTABLE;
 
@@ -2115,6 +2117,18 @@ static void i915_address_space_init(struct i915_address_space *vm,
 
 	list_add_tail(&vm->global_link, &dev_priv->vm_list);
 	pagevec_init(&vm->free_pages);
+
+	/*
+	 * The vm->mutex must be reclaim safe (for use in the shrinker).
+	 * Do a dummy acquire now under fs_reclaim so that any allocation
+	 * attempt holding the lock is immediately reported by lockdep.
+	 */
+	if (IS_ENABLED(CONFIG_LOCKDEP)) {
+		fs_reclaim_acquire(GFP_KERNEL);
+		mutex_lock(&vm->mutex);
+		mutex_unlock(&vm->mutex);
+		fs_reclaim_release(GFP_KERNEL);
+	}
 }
 
 static void i915_address_space_fini(struct i915_address_space *vm)
@@ -2124,6 +2138,8 @@ static void i915_address_space_fini(struct i915_address_space *vm)
 
 	drm_mm_takedown(&vm->mm);
 	list_del(&vm->global_link);
+
+	mutex_destroy(&vm->mutex);
 }
 
 static void gtt_write_workarounds(struct drm_i915_private *dev_priv)
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
index ba4d6e93abdf..eff01351d96f 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.h
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
@@ -289,6 +289,8 @@ struct i915_address_space {
 
 	bool closed;
 
+	struct mutex mutex; /* protects vma and our lists */
+
 	struct i915_page_dma scratch_page;
 	struct i915_page_table *scratch_pt;
 	struct i915_page_directory *scratch_pd;
-- 
2.18.0.rc2