--- libmalloc/libmalloc-374.100.5/tests/nano_tests.c
+++ libmalloc/libmalloc-283/tests/nano_tests.c
@@ -319,8 +319,7 @@
 #define ALLOCS_PER_ARENA ((NANOV2_ARENA_SIZE)/256)
 
 T_DECL(overspill_arena, "force overspill of an arena",
-	   T_META_ENVVAR("MallocNanoZone=V2"),
-	   T_META_ENVVAR("MallocGuardEdges=all"))
+	   T_META_ENVVAR("MallocNanoZone=V2"))
 {
 #if CONFIG_NANOZONE
 	void **ptrs = calloc(ALLOCS_PER_ARENA, sizeof(void *));
@@ -342,10 +341,6 @@
 		if (current_ptr.fields.nano_arena != first_ptr.fields.nano_arena) {
 			break;
 		}
-
-		// Write to the pointer to ensure the containing block is not
-		// a guard block.
-		*(int *)ptrs[index] = 0;
 	}
 
 	// Free everything, which is a check that the book-keeping works across
@@ -364,7 +359,7 @@
 // Guaranteed number of 256-byte allocations to be sure we fill a region.
 #define ALLOCS_PER_REGION ((NANOV2_REGION_SIZE)/256)
 
-// These tests are required only on macOS because iOS only uses one region.
+// This test is required only on macOS because iOS only uses one region.
 T_DECL(overspill_region, "force overspill of a region",
 	   T_META_ENVVAR("MallocNanoZone=V2"))
 {
@@ -400,111 +395,5 @@
 	T_SKIP("Nano allocator not configured");
 #endif // CONFIG_NANOZONE
 }
-
-void *
-punch_holes_thread(void *arg)
-{
-	T_LOG("Starting holes thread");
-	bool *done = arg;
-
-	bool holes[1024] = { false };
-	while (!os_atomic_load(done, relaxed)) {
-		bool allocate = random() % 2;
-		int which = random() % 1024;
-		uintptr_t base = NANOZONE_BASE_REGION_ADDRESS;
-		size_t len = 128ull * 1024ull * 1024ull;
-		size_t stride = 512ull * 1024ull * 1024ull;
-		uint64_t offset = stride * which;
-		void *addr = (void *)(base + offset);
-
-		if (allocate && !holes[which]) {
-			void *hole = mmap(addr, len, PROT_NONE, MAP_ANON | MAP_PRIVATE, -1, 0);
-			if (hole == addr) {
-				holes[which] = true;
-				T_LOG("punched hole %d (%p, %p)", which, hole, addr);
-			} else if (hole != MAP_FAILED) {
-				T_LOG("failed to punch hole %d (wanted %p, got %p), unmapping", which,
-						addr, hole);
-				munmap(hole, len);
-			}
-		} else if (!allocate && holes[which]) {
-			munmap(addr, len);
-			holes[which] = false;
-			T_LOG("unmapped hole %d", which);
-		}
-
-		usleep(300);
-	}
-
-	return NULL;
-}
-
-void *
-do_allocations_thread(void *arg)
-{
-	bool *done = arg;
-
-	size_t n = (256ull << 20) / 128;
-	void **allocations = malloc(n * sizeof(void *));
-	T_ASSERT_NOTNULL(allocations, "allocations");
-
-	while (!os_atomic_load(done, relaxed)) {
-		for (int i = 0; i < n; i++) {
-			allocations[i] = malloc(128);
-		}
-
-		usleep(100);
-
-		for (int i = 0; i < n; i++) {
-			free(allocations[i]);
-		}
-
-		usleep(50000 * ((random() % 8) + 1));
-	}
-
-	free(allocations);
-
-	return NULL;
-}
-
-T_DECL(region_holes, "ensure correct handling of holes between regions",
-		T_META_ENVVAR("MallocNanoZone=V2"))
-{
-#if CONFIG_NANOZONE
-	srandom(time(NULL));
-
-	bool done = false;
-
-	pthread_t holes_thread;
-	int rc = pthread_create(&holes_thread, NULL, punch_holes_thread, &done);
-	T_ASSERT_POSIX_ZERO(rc, "pthread_create");
-
-	int nthreads = 4;
-	pthread_t allocation_threads[nthreads];
-	for (int i = 0; i < nthreads; i++) {
-		rc = pthread_create(&allocation_threads[i], NULL, do_allocations_thread,
-				&done);
-		T_ASSERT_POSIX_ZERO(rc, "pthread_create");
-	}
-
-	sleep(4); // arbitrary time to try to hit the race
-
-	os_atomic_store(&done, true, relaxed);
-
-	rc = pthread_join(holes_thread, NULL);
-	T_ASSERT_POSIX_ZERO(rc, "pthread_join");
-
-	for (int i = 0; i < nthreads; i++) {
-		rc = pthread_join(allocation_threads[i], NULL);
-		T_ASSERT_POSIX_ZERO(rc, "pthread_join");
-	}
-
-	T_PASS("Didn't crash");
-	T_END;
-#else // CONFIG_NANOZONE
-	T_SKIP("Nano allocator not configured");
-#endif // CONFIG_NANOZONE
-}
-
 #endif // TARGET_OS_OSX