delay allocating slab metadata from reservation

malloc.c

@@ -176,7 +176,7 @@ static struct slab_metadata *alloc_metadata(struct size_class *c, size_t slab_si
             errno = ENOMEM;
             return NULL;
         }
-        size_t allocate = c->metadata_allocated * 2;
+        size_t allocate = max(c->metadata_allocated * 2, PAGE_SIZE / sizeof(struct slab_metadata));
         if (allocate > metadata_max) {
             allocate = metadata_max;
         }
@@ -825,10 +825,6 @@ COLD static void init_slow_path(void) {
         if (c->slab_info == NULL) {
             fatal_error("failed to allocate slab metadata");
         }
-        c->metadata_allocated = PAGE_SIZE / sizeof(struct slab_metadata);
-        if (memory_protect_rw(c->slab_info, c->metadata_allocated * sizeof(struct slab_metadata))) {
-            fatal_error("failed to allocate initial slab info");
-        }
     }
 
     deallocate_pages(rng, sizeof(struct random_state), PAGE_SIZE);

util.h

@@ -7,6 +7,18 @@
 #define likely(x) __builtin_expect(!!(x), 1)
 #define unlikely(x) __builtin_expect(!!(x), 0)
 
+#define min(x, y) ({ \
+    __typeof__(x) _x = (x); \
+    __typeof__(y) _y = (y); \
+    (void) (&_x == &_y); \
+    _x < _y ? _x : _y; })
+
+#define max(x, y) ({ \
+    __typeof__(x) _x = (x); \
+    __typeof__(y) _y = (y); \
+    (void) (&_x == &_y); \
+    _x > _y ? _x : _y; })
+
 #define COLD __attribute__((cold))
 #define UNUSED __attribute__((unused))
 #define EXPORT __attribute__((visibility("default")))