Add a mutex into struct i915_address_space to be used while operating on
the vma and their lists for a particular vm. As this may be called from
the shrinker, we taint the mutex with fs_reclaim so that from the start
lockdep warns us if we are caught holding the mutex across an
allocation. (With such small steps we will eventually rid ourselves of
struct_mutex recursion!)
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_drv.h | 2 +-
drivers/gpu/drm/i915/i915_gem_gtt.c | 10 ++++++++++
drivers/gpu/drm/i915/i915_gem_gtt.h | 2 ++
drivers/gpu/drm/i915/i915_gem_shrinker.c | 12 ++++++++++++
4 files changed, 25 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index eeb002a47032..01dd29837233 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -3304,7 +3304,7 @@ unsigned long i915_gem_shrink(struct drm_i915_private *i915,
unsigned long i915_gem_shrink_all(struct drm_i915_private *i915);
void i915_gem_shrinker_register(struct drm_i915_private *i915);
void i915_gem_shrinker_unregister(struct drm_i915_private *i915);
-
+void i915_gem_shrinker_taints_mutex(struct mutex *mutex);
/* i915_gem_tiling.c */
static inline bool i915_gem_object_needs_bit17_swizzle(struct drm_i915_gem_object *obj)
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index abd81fb9b0b6..d0acef299b9c 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -531,6 +531,14 @@ static void vm_free_page(struct i915_address_space *vm, struct page *page)
static void i915_address_space_init(struct i915_address_space *vm,
struct drm_i915_private *dev_priv)
{
+ /*
+ * 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.
+ */
+ mutex_init(&vm->mutex);
+ i915_gem_shrinker_taints_mutex(&vm->mutex);
+
GEM_BUG_ON(!vm->total);
drm_mm_init(&vm->mm, 0, vm->total);
vm->mm.head_node.color = I915_COLOR_UNEVICTABLE;
@@ -551,6 +559,8 @@ static void i915_address_space_fini(struct i915_address_space *vm)
spin_unlock(&vm->free_pages.lock);
drm_mm_takedown(&vm->mm);
+
+ mutex_destroy(&vm->mutex);
}
static int __setup_page_dma(struct i915_address_space *vm,
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
index feda45dfd481..14e62651010b 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.h
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
@@ -293,6 +293,8 @@ 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;
diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c b/drivers/gpu/drm/i915/i915_gem_shrinker.c
index c61f5b80fee3..ea90d3a0d511 100644
--- a/drivers/gpu/drm/i915/i915_gem_shrinker.c
+++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c
@@ -23,6 +23,7 @@
*/
#include <linux/oom.h>
+#include <linux/sched/mm.h>
#include <linux/shmem_fs.h>
#include <linux/slab.h>
#include <linux/swap.h>
@@ -531,3 +532,14 @@ void i915_gem_shrinker_unregister(struct drm_i915_private *i915)
WARN_ON(unregister_oom_notifier(&i915->mm.oom_notifier));
unregister_shrinker(&i915->mm.shrinker);
}
+
+void i915_gem_shrinker_taints_mutex(struct mutex *mutex)
+{
+ if (!IS_ENABLED(CONFIG_LOCKDEP))
+ return;
+
+ fs_reclaim_acquire(GFP_KERNEL);
+ mutex_lock(mutex);
+ mutex_unlock(mutex);
+ fs_reclaim_release(GFP_KERNEL);
+}
--
2.18.0
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