Avoid full-list scans for C7 v4 and tighten partial reuse

core/smallobject_hotbox_v4.c

@@ -97,14 +97,7 @@ static small_page_v4* v4_find_page(small_class_heap_v4* h, const uint8_t* ptr, v
             return p;
         }
     }
-    prev = NULL;
-    for (small_page_v4* p = h->full_head; p; prev = p, p = p->next) {
-        if (v4_ptr_in_page(p, ptr)) {
-            if (loc) *loc = V4_LOC_FULL;
-            if (prev_out) *prev_out = prev;
-            return p;
-        }
-    }
+    // full リストは探さない（v4 C7 は partial/current だけで完結する想定）
     return NULL;
 }
 
@@ -301,8 +294,12 @@ void small_heap_free_fast_v4(small_heap_ctx_v4* ctx, int class_idx, void* ptr) {
         h->current = page;
         page->next = NULL;
     } else if (loc == V4_LOC_FULL && page->freelist) {
-        // full → partial に戻す
+        // full → partial に戻す（current があっても partial 上限までは復帰）
         v4_unlink_from_list(h, loc, prev, page);
-        v4_page_push_partial(h, page);
+        if (h->partial_count < V4_MAX_PARTIAL_PAGES) {
+            v4_page_push_partial(h, page);
+        } else {
+            v4_page_push_full(h, page);  // 上限超なら戻す
+        }
     }
 }