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drm/buddy: Integrate lockdep annotations for gpu buddy manager

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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
This commit is contained in:
Tejas Upadhyay
2026-05-08 12:25:45 +05:30
committed by Arunpravin Paneer Selvam
parent c2738d88b6
commit 35b535db69
4 changed files with 54 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
drivers/gpu/buddy.c
View File

@@ -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);

1
drivers/gpu/drm/drm_buddy.c
View File

@@ -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);

1
drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
View File

@@ -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);

41
include/linux/gpu_buddy.h
View File

@@ -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)
{