From: Michael Anthony Knyszek <mknyszek@google.com>
Date: Wed, 19 Dec 2018 17:32:22 +0000 (+0000)
Subject: runtime: disable TestArenaCollision on Darwin in race mode
X-Git-Tag: go1.12beta2~111
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=6fcab648af59faab639f3453354a7a14c888e75c;p=gostls13.git

runtime: disable TestArenaCollision on Darwin in race mode

This change disables the test TestArenaCollision on Darwin in race mode
to deal with the fact that Darwin 10.10 must use MAP_FIXED in race mode
to ensure we retain our heap in a particular portion of the address
space which the race detector needs. The test specifically checks to
make sure a manually mapped region's space isn't re-used, which is
definitely possible with MAP_FIXED because it replaces whatever mapping
already exists at a given address.

This change then also makes it so that MAP_FIXED is only used in race
mode and on Darwin, not all BSDs, because using MAP_FIXED breaks this
test for FreeBSD in addition to Darwin.

Updates #26475.
Fixes #29340.

Change-Id: I1c59349408ccd7eeb30c4bf2593f48316b23ab2f
Reviewed-on: https://go-review.googlesource.com/c/155097
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
---

diff --git a/src/runtime/malloc_test.go b/src/runtime/malloc_test.go
index f25bfa48af..a2d5864d3d 100644
--- a/src/runtime/malloc_test.go
+++ b/src/runtime/malloc_test.go
@@ -183,6 +183,14 @@ type acLink struct {
 var arenaCollisionSink []*acLink
 
 func TestArenaCollision(t *testing.T) {
+	if GOOS == "darwin" && race.Enabled {
+		// Skip this test on Darwin in race mode because Darwin 10.10 has
+		// issues following arena hints and runs out of them in race mode, so
+		// MAP_FIXED is used to ensure we keep the heap in the memory region the
+		// race detector expects.
+		// TODO(mknyszek): Delete this when Darwin 10.10 is no longer supported.
+		t.Skip("disabled on Darwin with race mode since MAP_FIXED is used")
+	}
 	testenv.MustHaveExec(t)
 
 	// Test that mheap.sysAlloc handles collisions with other
diff --git a/src/runtime/mem_bsd.go b/src/runtime/mem_bsd.go
index bf2d99678b..84238d7279 100644
--- a/src/runtime/mem_bsd.go
+++ b/src/runtime/mem_bsd.go
@@ -43,7 +43,7 @@ func sysFault(v unsafe.Pointer, n uintptr) {
 
 func sysReserve(v unsafe.Pointer, n uintptr) unsafe.Pointer {
 	flags := int32(_MAP_ANON | _MAP_PRIVATE)
-	if raceenabled {
+	if raceenabled && GOOS == "darwin" {
 		// Currently the race detector expects memory to live within a certain
 		// range, and on Darwin 10.10 mmap is prone to ignoring hints, moreso
 		// than later versions and other BSDs (#26475). So, even though it's