runtime: reenable bad pointer check in GC

The last time we tried this, linux/arm64 broke.
The series of CLs leading to this one fixes that problem.
Let's try again.

Fixes #9880.

Change-Id: I67bc1d959175ec972d4dcbe4aa6f153790f74251
Reviewed-on: https://go-review.googlesource.com/12849
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

diff --git a/src/runtime/mbitmap.go b/src/runtime/mbitmap.go
index ef17409ebeb73cc57a4161eacae415cd462853f2..b9b52a7bc416f8974a465534a9b9fa2579d0033c 100644 (file)
--- a/src/runtime/mbitmap.go
+++ b/src/runtime/mbitmap.go
@@ -201,7 +201,7 @@ func heapBitsForObject(p uintptr) (base uintptr, hbits heapBits, s *mspan) {
                // The following ensures that we are rigorous about what data
                // structures hold valid pointers.
                // TODO(rsc): Check if this still happens.
-               if false {
+               if true {
                        // Still happens sometimes. We don't know why.
                        printlock()
                        print("runtime:objectstart Span weird: p=", hex(p), " k=", hex(k))