JEMALLOC_INLINE_C void
arena_run_reg_dalloc(arena_run_t *run, void *ptr)
{
	arena_chunk_t *chunk = (arena_chunk_t *)CHUNK_ADDR2BASE(run);
	size_t pageind = ((uintptr_t)ptr - (uintptr_t)chunk) >> LG_PAGE;
	size_t mapbits = arena_mapbits_get(chunk, pageind);
	szind_t binind = arena_ptr_small_binind_get(ptr, mapbits);
	arena_bin_info_t *bin_info = &arena_bin_info[binind];
	unsigned regind = arena_run_regind(run, bin_info, ptr);

	assert(run->nfree < bin_info->nregs);
	/* Freeing an interior pointer can cause assertion failure. */
	assert(((uintptr_t)ptr -
	    ((uintptr_t)arena_miscelm_to_rpages(arena_run_to_miscelm(run)) +
	    (uintptr_t)bin_info->reg0_offset)) %
	    (uintptr_t)bin_info->reg_interval == 0);
	assert((uintptr_t)ptr >=
	    (uintptr_t)arena_miscelm_to_rpages(arena_run_to_miscelm(run)) +
	    (uintptr_t)bin_info->reg0_offset);
	/* Freeing an unallocated pointer can cause assertion failure. */
	assert(bitmap_get(run->bitmap, &bin_info->bitmap_info, regind));

	bitmap_unset(run->bitmap, &bin_info->bitmap_info, regind);
	run->nfree++;
}