Merge branch 'PHP-7.3'

* PHP-7.3:
  Revert "Support fixed address mmap without replacement"
  Revert "Don't report mmap failure if it is expected"

Author: remicollet

Zend/zend_alloc.c

@@ -423,16 +423,11 @@ static void *zend_mm_mmap_fixed(void *addr, size_t size)
 #ifdef _WIN32
 	return VirtualAlloc(addr, size, MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
 #else
-	int flags = MAP_PRIVATE | MAP_ANON;
-#ifdef MAP_FIXED_NOREPLACE
-	flags |= MAP_FIXED_NOREPLACE;
-#elif defined MAP_EXCL
-	flags |= MAP_FIXED | MAP_EXCL;
-#endif
-	void *ptr = mmap(addr, size, PROT_READ | PROT_WRITE, flags /*| MAP_POPULATE | MAP_HUGETLB*/, -1, 0);
+	/* MAP_FIXED leads to discarding of the old mapping, so it can't be used. */
+	void *ptr = mmap(addr, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON /*| MAP_POPULATE | MAP_HUGETLB*/, -1, 0);
 
 	if (ptr == MAP_FAILED) {
-#if ZEND_MM_ERROR && !defined(MAP_FIXED_NOREPLACE) && !defined(MAP_EXCL)
+#if ZEND_MM_ERROR
 		fprintf(stderr, "\nmmap() failed: [%d] %s\n", errno, strerror(errno));
 #endif
 		return NULL;