diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE
index e2d91ad222c4..416a5876da88 100644
--- a/gcc/go/gofrontend/MERGE
+++ b/gcc/go/gofrontend/MERGE
@@ -1,4 +1,4 @@
-fc0cfdff94ca1099421900f43837ca5a70189cd6
+0a20181d00d43a423c55f4e772b759fba0619478
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.
diff --git a/libgo/go/runtime/cgo_gccgo.go b/libgo/go/runtime/cgo_gccgo.go
index b0ad2f12a635..8236eeabf467 100644
--- a/libgo/go/runtime/cgo_gccgo.go
+++ b/libgo/go/runtime/cgo_gccgo.go
@@ -95,9 +95,34 @@ func CgocallBack() {
 // CgocallBackDone prepares to return to C/C++ code that has called
 // into Go code.
 func CgocallBackDone() {
+	// If we are the top level Go function called from C/C++, then
+	// we need to release the m. But don't release it if we are
+	// panicing; since this is the top level, we are going to
+	// crash the program, and we need the g and m to print the
+	// panic values.
+	//
+	// Dropping the m is going to clear g. This function is being
+	// called as a deferred function, so we will return to
+	// deferreturn which will want to clear the _defer field.
+	// As soon as we call dropm another thread may call needm and
+	// start using g, so we must not tamper with the _defer field
+	// after dropm. So clear _defer now.
+	gp := getg()
+	mp := gp.m
+	drop := false
+	if mp.dropextram && mp.ncgo == 0 && gp._panic == nil {
+		d := gp._defer
+		if d == nil || d.link != nil {
+			throw("unexpected g._defer in CgocallBackDone")
+		}
+		gp._defer = nil
+		freedefer(d)
+		drop = true
+	}
+
 	entersyscall(0)
-	mp := getg().m
-	if mp.dropextram && mp.ncgo == 0 {
+
+	if drop {
 		mp.dropextram = false
 		dropm()
 	}
diff --git a/libgo/go/runtime/panic.go b/libgo/go/runtime/panic.go
index e3d03580de5c..43d595f667e7 100644
--- a/libgo/go/runtime/panic.go
+++ b/libgo/go/runtime/panic.go
@@ -143,14 +143,6 @@ func newdefer() *_defer {
 //
 //go:nosplit
 func freedefer(d *_defer) {
-	// When C code calls a Go function on a non-Go thread, the
-	// deferred call to cgocallBackDone will set g to nil.
-	// Don't crash trying to put d on the free list; just let it
-	// be garbage collected.
-	if getg() == nil {
-		return
-	}
-
 	pp := getg().m.p.ptr()
 	if len(pp.deferpool) == cap(pp.deferpool) {
 		// Transfer half of local cache to the central cache.
@@ -201,6 +193,15 @@ func deferreturn(frame *bool) {
 			fn(d.arg)
 		}
 
+		// If we are returning from a Go function called by a
+		// C function running in a C thread, g may now be nil,
+		// in which case CgocallBackDone will have cleared _defer.
+		// In that case some other goroutine may already be using gp.
+		if getg() == nil {
+			*frame = true
+			return
+		}
+
 		gp._defer = d.link
 
 		freedefer(d)