From 9c223a1e4823047fa0143a125baef4e6a10976f5 Mon Sep 17 00:00:00 2001
From: Richard Shin <shin.richard@gmail.com>
Date: Thu, 29 Sep 2016 23:46:04 -0700
Subject: [PATCH] Increase dlmalloc's granularity to 1 << 25 (#30)

* Increase dlmalloc's granularity to 1 << 10

* Prevent trimming in dlmalloc
---
 src/malloc.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/malloc.c b/src/malloc.c
index f18535437..fbf8c8d92 100644
--- a/src/malloc.c
+++ b/src/malloc.c
@@ -18,6 +18,7 @@ int fake_munmap(void *, size_t);
 #define DIRECT_MUNMAP(a, s) fake_munmap(a, s)
 #define USE_DL_PREFIX
 #define HAVE_MORECORE 0
+#define DEFAULT_GRANULARITY ((size_t) 1U << 25)
 
 #include "thirdparty/dlmalloc.c"
 
@@ -27,6 +28,7 @@ int fake_munmap(void *, size_t);
 #undef DIRECT_MUNMAP
 #undef USE_DL_PREFIX
 #undef HAVE_MORECORE
+#undef DEFAULT_GRANULARITY
 
 struct mmap_record {
   int fd;
@@ -98,7 +100,11 @@ int fake_munmap(void *addr, size_t size) {
   struct mmap_record *record;
 
   HASH_FIND(hh_pointer, records_by_pointer, &addr, sizeof(addr), record);
-  assert(record != NULL);
+  if (record == NULL || record->size != size) {
+    /* Reject requests to munmap that don't directly match previous
+     * calls to mmap, to prevent dlmalloc from trimming. */
+    return -1;
+  }
   close(record->fd);
 
   HASH_DELETE(hh_fd, records_by_fd, record);