sdt_chunk
struct sdt_chunk __arena *chunk;
_Static_assert(sizeof(struct sdt_chunk) <= PAGE_SIZE,
ret = pool_set_size(&chunk_pool, sizeof(struct sdt_chunk), 1);
struct sdt_chunk __arena *chunk;
struct sdt_chunk __arena *chunk;
struct sdt_chunk __arena *chunk;
struct sdt_chunk;
struct sdt_chunk __arena *chunk;