[PATCH] cgroup/dmem: Use size_t for try_charge() and uncharge() size

[hongfu.li@linux.dev]

From: Hongfu Li <hongfu.li@linux.dev>

The charge APIs currently accept the allocation size as u64, but every
caller passes a size_t value derived from drm_gem_object::size.
Using u64 is unnecessary and, on 32-bit architectures, may lead to
truncation when the value is later cast to unsigned long for internal
page_counter functions.

Change the public function signatures to take size_t instead of u64.
Inside the implementation, pass the size directly to
page_counter_try_charge() and page_counter_uncharge(), which already
expect unsigned long.

Signed-off-by: Hongfu Li <hongfu.li@linux.dev>
---
 include/linux/cgroup_dmem.h | 8 ++++----
 kernel/cgroup/dmem.c        | 4 ++--
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/linux/cgroup_dmem.h b/include/linux/cgroup_dmem.h
index dd4869f1d736..ed7440eb9c28 100644
--- a/include/linux/cgroup_dmem.h
+++ b/include/linux/cgroup_dmem.h
@@ -17,10 +17,10 @@ struct dmem_cgroup_region;
 #if IS_ENABLED(CONFIG_CGROUP_DMEM)
 struct dmem_cgroup_region *dmem_cgroup_register_region(u64 size, const char *name_fmt, ...) __printf(2,3);
 void dmem_cgroup_unregister_region(struct dmem_cgroup_region *region);
-int dmem_cgroup_try_charge(struct dmem_cgroup_region *region, u64 size,
+int dmem_cgroup_try_charge(struct dmem_cgroup_region *region, size_t size,
 			   struct dmem_cgroup_pool_state **ret_pool,
 			   struct dmem_cgroup_pool_state **ret_limit_pool);
-void dmem_cgroup_uncharge(struct dmem_cgroup_pool_state *pool, u64 size);
+void dmem_cgroup_uncharge(struct dmem_cgroup_pool_state *pool, size_t size);
 bool dmem_cgroup_state_evict_valuable(struct dmem_cgroup_pool_state *limit_pool,
 				      struct dmem_cgroup_pool_state *test_pool,
 				      bool ignore_low, bool *ret_hit_low);
@@ -36,7 +36,7 @@ dmem_cgroup_register_region(u64 size, const char *name_fmt, ...)
 static inline void dmem_cgroup_unregister_region(struct dmem_cgroup_region *region)
 { }
 
-static inline int dmem_cgroup_try_charge(struct dmem_cgroup_region *region, u64 size,
+static inline int dmem_cgroup_try_charge(struct dmem_cgroup_region *region, size_t size,
 					 struct dmem_cgroup_pool_state **ret_pool,
 					 struct dmem_cgroup_pool_state **ret_limit_pool)
 {
@@ -48,7 +48,7 @@ static inline int dmem_cgroup_try_charge(struct dmem_cgroup_region *region, u64
 	return 0;
 }
 
-static inline void dmem_cgroup_uncharge(struct dmem_cgroup_pool_state *pool, u64 size)
+static inline void dmem_cgroup_uncharge(struct dmem_cgroup_pool_state *pool, size_t size)
 { }
 
 static inline
diff --git a/kernel/cgroup/dmem.c b/kernel/cgroup/dmem.c
index 4753a67d0f0f..38108536d2d6 100644
--- a/kernel/cgroup/dmem.c
+++ b/kernel/cgroup/dmem.c
@@ -619,7 +619,7 @@ get_cg_pool_unlocked(struct dmemcg_state *cg, struct dmem_cgroup_region *region)
  * Must be called with the returned pool as argument,
  * and same @index and @size.
  */
-void dmem_cgroup_uncharge(struct dmem_cgroup_pool_state *pool, u64 size)
+void dmem_cgroup_uncharge(struct dmem_cgroup_pool_state *pool, size_t size)
 {
 	if (!pool)
 		return;
@@ -649,7 +649,7 @@ EXPORT_SYMBOL_GPL(dmem_cgroup_uncharge);
  *
  * Return: 0 on success, -EAGAIN on hitting a limit, or a negative errno on failure.
  */
-int dmem_cgroup_try_charge(struct dmem_cgroup_region *region, u64 size,
+int dmem_cgroup_try_charge(struct dmem_cgroup_region *region, size_t size,
 			  struct dmem_cgroup_pool_state **ret_pool,
 			  struct dmem_cgroup_pool_state **ret_limit_pool)
 {
-- 
2.54.0