the simple expression has the same precision without overflow
diff --git a/src/core/ngx_slab.c b/src/core/ngx_slab.c
index daf5639..9f63a91 100644
--- a/src/core/ngx_slab.c
+++ b/src/core/ngx_slab.c
@@ -111,10 +111,7 @@
p += n * sizeof(ngx_slab_page_t);
- /* STUB: possible overflow on 64-bit platform */
- pages = (ngx_uint_t) ((uint64_t) size * ngx_pagesize
- / (ngx_pagesize + sizeof(ngx_slab_page_t))
- / ngx_pagesize);
+ pages = (ngx_uint_t) (size / (ngx_pagesize + sizeof(ngx_slab_page_t)));
ngx_memzero(p, pages * sizeof(ngx_slab_page_t));