diff --git a/kernel/sched/ext/arena.c b/kernel/sched/ext/arena.c
index b0e6a0be4913..f7a9f633f435 100644
--- a/kernel/sched/ext/arena.c
+++ b/kernel/sched/ext/arena.c
@@ -6,8 +6,7 @@
  *
  * Each chunk added to @sch->arena_pool comes from one
  * bpf_arena_alloc_pages_sleepable() call and is registered at the
- * kernel-side mapping address. Callers translate to the BPF-arena form
- * themselves if needed.
+ * kernel-side mapping address.
  *
  * Allocations grow the pool on demand. Underlying arena pages are released
  * when the arena map itself is torn down.
diff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c
index 61b156d7fc4b..c12327b6d541 100644
--- a/kernel/sched/ext/ext.c
+++ b/kernel/sched/ext/ext.c
@@ -467,13 +467,14 @@ static inline void scx_call_op_set_cpumask(struct scx_sched *sch, struct rq *rq,
 
 		/*
 		 * Build the per-cpu arena cmask from kernel geometry via @ref,
-		 * never reading its BPF-writable header, and hand BPF the arena
-		 * address. The rq lock makes this cpu the sole kernel writer.
+		 * never reading its BPF-writable header. set_cmask()'s __arena
+		 * argument takes the kernel address and the struct_ops
+		 * trampoline rebases it into BPF's arena pointer form. The rq
+		 * lock makes this cpu the sole kernel writer.
 		 */
 		scx_cmask_ref_init_kern(sch, kern_va, 0, num_possible_cpus(), &ref);
 		scx_cmask_ref_from_cpumask(&ref, cpumask);
-		SCX_CALL_CID_OP_TASK(sch, set_cmask, rq, task,
-				     scx_kaddr_to_arena(sch, kern_va));
+		SCX_CALL_CID_OP_TASK(sch, set_cmask, rq, task, kern_va);
 	} else {
 		SCX_CALL_OP_TASK(sch, set_cpumask, rq, task, cpumask);
 	}
@@ -8339,9 +8340,8 @@ static struct bpf_struct_ops bpf_sched_ext_ops = {
  * fresh stubs, set_cmask due to an argument type difference and the sub-sched
  * notifiers because no cpu-form stub exists to reuse.
  */
-static void sched_ext_ops_cid__set_cmask(struct task_struct *p,
-					 const struct scx_cmask *cmask) {}
-static void sched_ext_ops__sub_caps_updated(const struct scx_cmask *cmask, u64 caps) {}
+static void sched_ext_ops_cid__set_cmask(struct task_struct *p, const struct scx_cmask *cmask__arena) {}
+static void sched_ext_ops__sub_caps_updated(const struct scx_cmask *cmask__arena, u64 caps) {}
 static void sched_ext_ops__sub_ecaps_updated(s32 cid, u64 before, u64 after) {}
 
 static struct sched_ext_ops_cid __bpf_ops_sched_ext_ops_cid = {
diff --git a/kernel/sched/ext/internal.h b/kernel/sched/ext/internal.h
index b699e7c1103f..35b5bf8c5c66 100644
--- a/kernel/sched/ext/internal.h
+++ b/kernel/sched/ext/internal.h
@@ -1049,7 +1049,7 @@ struct sched_ext_ops_cid {
 				   struct task_struct *b);
 	void (*set_weight)(struct task_struct *p, u32 weight);
 	void (*set_cmask)(struct task_struct *p,
-			   const struct scx_cmask *cmask);
+			   const struct scx_cmask *cmask__arena);
 	void (*update_idle)(s32 cid, bool idle);
 	s32 (*init_task)(struct task_struct *p,
 			  struct scx_init_task_args *args);
@@ -1075,7 +1075,7 @@ struct sched_ext_ops_cid {
 #endif	/* CONFIG_EXT_GROUP_SCHED */
 	s32 (*sub_attach)(struct scx_sub_attach_args *args);
 	void (*sub_detach)(struct scx_sub_detach_args *args);
-	void (*sub_caps_updated)(const struct scx_cmask *cmask, u64 caps);
+	void (*sub_caps_updated)(const struct scx_cmask *cmask__arena, u64 caps);
 	void (*sub_ecaps_updated)(s32 cid, u64 before, u64 after);
 	void (*cid_online)(s32 cid);
 	void (*cid_offline)(s32 cid);
@@ -1534,8 +1534,7 @@ struct scx_sched {
 	 *
 	 * @arena_pool sub-allocates @arena_map. Each gen_pool chunk is added
 	 * at the kernel-side mapping address. @arena_kern_base is the start
-	 * of the arena's kern_vm range. See scx_arena_to_kaddr() and
-	 * scx_kaddr_to_arena().
+	 * of the arena's kern_vm range. See scx_arena_to_kaddr().
 	 */
 	struct bpf_map		*arena_map;
 	struct gen_pool		*arena_pool;
@@ -1544,7 +1543,7 @@ struct scx_sched {
 	/*
 	 * Per-CPU arena cmask used by scx_call_op_set_cpumask() to hand a cmask
 	 * to ops_cid.set_cmask(). The kernel writes through the stored kern_va
-	 * and hands BPF its arena pointer via scx_kaddr_to_arena().
+	 * and passes it to the callback's __arena argument.
 	 */
 	struct scx_cmask * __percpu *set_cmask_scratch;
 
@@ -1654,16 +1653,6 @@ static inline void *scx_arena_to_kaddr(struct scx_sched *sch, const void *bpf_pt
 	return (void *)(sch->arena_kern_base + (u32)(uintptr_t)bpf_ptr);
 }
 
-/**
- * scx_kaddr_to_arena - Translate a kernel arena address to its BPF form
- * @sch: scheduler whose arena hosts @kaddr
- * @kaddr: kernel-side arena address, supplied by trusted kernel code
- */
-static inline void *scx_kaddr_to_arena(struct scx_sched *sch, const void *kaddr)
-{
-	return (void *)((uintptr_t)kaddr - sch->arena_kern_base);
-}
-
 enum scx_wake_flags {
 	/* expose select WF_* flags as enums */
 	SCX_WAKE_FORK		= WF_FORK,
diff --git a/kernel/sched/ext/sub.c b/kernel/sched/ext/sub.c
index 3bd12c1ff0a3..0978581d8c8e 100644
--- a/kernel/sched/ext/sub.c
+++ b/kernel/sched/ext/sub.c
@@ -870,9 +870,7 @@ static void caps_updated_deliver(struct list_head *to_deliver)
 				break;
 
 			/* caps != 0 only when deliverable (has_op, above) */
-			SCX_CALL_OP(sch, sub_caps_updated, NULL,
-				    scx_kaddr_to_arena(sch, cu->cmask_arena_out),
-				    caps);
+			SCX_CALL_OP(sch, sub_caps_updated, NULL, cu->cmask_arena_out, caps);
 		}
 	}
 }