From b097b47aa21a4bd7da9c87f156f68acecd621537 Mon Sep 17 00:00:00 2001
From: Matthew Parkinson <mattpark@microsoft.com>
Date: Thu, 17 Jan 2019 14:05:38 +0000
Subject: [PATCH] Handle 2^16 slabs

This code assumes that 16bit uint wrapping can be used, rather than
masking by SLAB_SIZE-1.  Add explicit mask, so we can change the
SLAB_SIZE to be smaller.
---
 src/mem/slab.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/mem/slab.h b/src/mem/slab.h
index 33138d9..ec9a000 100644
--- a/src/mem/slab.h
+++ b/src/mem/slab.h
@@ -58,7 +58,7 @@ namespace snmalloc
       {
         // This slab is being bump allocated.
         p = (void*)((size_t)this + head - 1);
-        meta->head = head + (uint16_t)rsize;
+        meta->head = (head + (uint16_t)rsize) & (SLAB_SIZE - 1);
         if (meta->head == 1)
         {
           meta->set_full();