drm/buddy: Integrate lockdep annotations for gpu buddy manager

gpu_buddy APIs are expected to be called with the driver-provided lock
held, but there is no runtime enforcement of this contract. Add lockdep
annotations to catch locking violations early.

Introduce gpu_buddy_driver_set_lock() for the driver to register the
lock that protects the buddy manager. Add gpu_buddy_driver_lock_held()
assertions to all exported gpu_buddy and drm_buddy APIs that
access/modify the manager state. The lock_dep_map field is only compiled
in when CONFIG_LOCKDEP is enabled, adding zero overhead to production
builds.

Wire up xe_ttm_vram_mgr to register its mutex with the buddy manager
after initialization.

Assisted-by: Copilot:claude-opus-4.6
Suggested-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Tejas Upadhyay <tejas.upadhyay@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@amd.com>
Link: https://patch.msgid.link/20260508065544.4049240-2-tejas.upadhyay@intel.com

diff --git a/drivers/gpu/buddy.c b/drivers/gpu/buddy.c
index 52686672e99f561f0c3ece7973edc0c0f1c39c2e..eb1457376307d3d4f2a5458f8c2a48770f6f9b7b 100644 (file)
--- a/drivers/gpu/buddy.c
+++ b/drivers/gpu/buddy.c
@@ -437,6 +437,9 @@ int gpu_buddy_init(struct gpu_buddy *mm, u64 size, u64 chunk_size)
                root_count++;
        } while (size);
 
+#ifdef CONFIG_LOCKDEP
+       mm->lock_dep_map = NULL;
+#endif
        return 0;
 
 out_free_roots:
@@ -538,6 +541,7 @@ void gpu_buddy_reset_clear(struct gpu_buddy *mm, bool is_clear)
        unsigned int order;
        int i;
 
+       gpu_buddy_driver_lock_held(mm);
        size = mm->size;
        for (i = 0; i < mm->n_roots; ++i) {
                order = ilog2(size) - ilog2(mm->chunk_size);
@@ -580,6 +584,7 @@ EXPORT_SYMBOL(gpu_buddy_reset_clear);
 void gpu_buddy_free_block(struct gpu_buddy *mm,
                          struct gpu_buddy_block *block)
 {
+       gpu_buddy_driver_lock_held(mm);
        BUG_ON(!gpu_buddy_block_is_allocated(block));
        mm->avail += gpu_buddy_block_size(mm, block);
        if (gpu_buddy_block_is_clear(block))
@@ -633,6 +638,7 @@ void gpu_buddy_free_list(struct gpu_buddy *mm,
 {
        bool mark_clear = flags & GPU_BUDDY_CLEARED;
 
+       gpu_buddy_driver_lock_held(mm);
        __gpu_buddy_free_list(mm, objects, mark_clear, !mark_clear);
 }
 EXPORT_SYMBOL(gpu_buddy_free_list);
@@ -1172,6 +1178,8 @@ int gpu_buddy_block_trim(struct gpu_buddy *mm,
        u64 new_start;
        int err;
 
+       gpu_buddy_driver_lock_held(mm);
+
        if (!list_is_singular(blocks))
                return -EINVAL;
 
@@ -1287,6 +1295,8 @@ int gpu_buddy_alloc_blocks(struct gpu_buddy *mm,
        unsigned long pages;
        int err;
 
+       gpu_buddy_driver_lock_held(mm);
+
        if (size < mm->chunk_size)
                return -EINVAL;
 
@@ -1475,6 +1485,7 @@ void gpu_buddy_print(struct gpu_buddy *mm)
 {
        int order;
 
+       gpu_buddy_driver_lock_held(mm);
        pr_info("chunk_size: %lluKiB, total: %lluMiB, free: %lluMiB, clear_free: %lluMiB\n",
                mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20, mm->clear_avail >> 20);
 

diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c
index 841f3de5f307a07d17d3ff226bd5784ab8f5bd96..faa025498de452e2218685bf1d8c345f24c8ba53 100644 (file)
--- a/drivers/gpu/drm/drm_buddy.c
+++ b/drivers/gpu/drm/drm_buddy.c
@@ -42,6 +42,7 @@ void drm_buddy_print(struct gpu_buddy *mm, struct drm_printer *p)
 {
        int order;
 
+       gpu_buddy_driver_lock_held(mm);
        drm_printf(p, "chunk_size: %lluKiB, total: %lluMiB, free: %lluMiB, clear_free: %lluMiB\n",
                   mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20, mm->clear_avail >> 20);
 

diff --git a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
index 6ba47996bc7c106b88a31665b9218d23053189d8..9f67df646955c0f963ad369d6f2579d7b64f9871 100644 (file)
--- a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
+++ b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
@@ -322,6 +322,7 @@ int __xe_ttm_vram_mgr_init(struct xe_device *xe, struct xe_ttm_vram_mgr *mgr,
        if (err)
                return err;
 
+       gpu_buddy_driver_set_lock(&mgr->mm, &mgr->lock);
        ttm_set_driver_manager(&xe->ttm, mem_type, &mgr->manager);
        ttm_resource_manager_set_used(&mgr->manager, true);
 

diff --git a/include/linux/gpu_buddy.h b/include/linux/gpu_buddy.h
index 5fa917ba5450b3133812dd082887bcd630314738..71941a0396485f4aea4edaf5106fd1ce1ec03f49 100644 (file)
--- a/include/linux/gpu_buddy.h
+++ b/include/linux/gpu_buddy.h
@@ -154,6 +154,7 @@ struct gpu_buddy_block {
  * @avail: Total free space currently available for allocation in bytes.
  * @clear_avail: Free space available in the clear tree (zeroed memory) in bytes.
  *               This is a subset of @avail.
+ * @lock_dep_map: Annotates gpu_buddy API with a driver provided lock.
  */
 struct gpu_buddy {
 /* private: */
@@ -179,8 +180,48 @@ struct gpu_buddy {
        u64 size;
        u64 avail;
        u64 clear_avail;
+#ifdef CONFIG_LOCKDEP
+       struct lockdep_map *lock_dep_map;
+#endif
 };
 
+#ifdef CONFIG_LOCKDEP
+/**
+ * gpu_buddy_driver_set_lock() - Set the lock protecting accesses to GPU BUDDY
+ * @mm: Pointer to GPU buddy structure.
+ * @lock: the lock used to protect the gpu buddy. The locking primitive
+ * must contain a dep_map field.
+ *
+ * Call this to annotate gpu_buddy APIs which access/modify gpu_buddy manager
+ */
+#define gpu_buddy_driver_set_lock(mm, lock) \
+       do { \
+               struct gpu_buddy *__mm = (mm); \
+               if (!WARN(__mm->lock_dep_map, "GPU BUDDY MM lock should be set only once.")) \
+                       __mm->lock_dep_map = &(lock)->dep_map; \
+       } while (0)
+#else
+#define gpu_buddy_driver_set_lock(mm, lock) do { (void)(mm); (void)(lock); } while (0)
+#endif
+
+#ifdef CONFIG_LOCKDEP
+/**
+ * gpu_buddy_driver_lock_held() - Assert GPU BUDDY manager lock is held
+ * @mm: Pointer to the GPU BUDDY structure.
+ *
+ * Ensure driver lock is held.
+ */
+static inline void gpu_buddy_driver_lock_held(struct gpu_buddy *mm)
+{
+       if (mm->lock_dep_map)
+               lockdep_assert(lock_is_held_type(mm->lock_dep_map, 0));
+}
+#else
+static inline void gpu_buddy_driver_lock_held(struct gpu_buddy *mm)
+{
+}
+#endif
+
 static inline u64
 gpu_buddy_block_offset(const struct gpu_buddy_block *block)
 {