5 files changed, 31 insertions, 0 deletions
diff --git a/src/runtime/chan.go b/src/runtime/chan.go
index 0049701826..0eb87df74f 100644
--- a/src/runtime/chan.go
+++ b/src/runtime/chan.go
@@ -630,6 +630,7 @@ func (q *waitq) dequeue() *sudog {
 			return nil
 		}
 		q.first = sgp.next
+		sgp.next = nil
 		if q.last == sgp {
 			q.last = nil
 		}
diff --git a/src/runtime/mgc0.go b/src/runtime/mgc0.go
index 3a7204b54f..cbf5e9cfde 100644
--- a/src/runtime/mgc0.go
+++ b/src/runtime/mgc0.go
@@ -51,10 +51,26 @@ func clearpools() {
 		if c := p.mcache; c != nil {
 			c.tiny = nil
 			c.tinysize = 0
+
+			// disconnect cached list before dropping it on the floor,
+			// so that a dangling ref to one entry does not pin all of them.
+			var sg, sgnext *sudog
+			for sg = c.sudogcache; sg != nil; sg = sgnext {
+				sgnext = sg.next
+				sg.next = nil
+			}
 			c.sudogcache = nil
 		}
+
 		// clear defer pools
 		for i := range p.deferpool {
+			// disconnect cached list before dropping it on the floor,
+			// so that a dangling ref to one entry does not pin all of them.
+			var d, dlink *_defer
+			for d = p.deferpool[i]; d != nil; d = dlink {
+				dlink = d.link
+				d.link = nil
+			}
 			p.deferpool[i] = nil
 		}
 	}
diff --git a/src/runtime/proc.go b/src/runtime/proc.go
index 5b8c7d8ae9..517ca03df6 100644
--- a/src/runtime/proc.go
+++ b/src/runtime/proc.go
@@ -152,6 +152,7 @@ func acquireSudog() *sudog {
 			gothrow("acquireSudog: found s.elem != nil in cache")
 		}
 		c.sudogcache = s.next
+		s.next = nil
 		return s
 	}
 
@@ -177,6 +178,15 @@ func releaseSudog(s *sudog) {
 	if s.selectdone != nil {
 		gothrow("runtime: sudog with non-nil selectdone")
 	}
+	if s.next != nil {
+		gothrow("runtime: sudog with non-nil next")
+	}
+	if s.prev != nil {
+		gothrow("runtime: sudog with non-nil prev")
+	}
+	if s.waitlink != nil {
+		gothrow("runtime: sudog with non-nil waitlink")
+	}
 	gp := getg()
 	if gp.param != nil {
 		gothrow("runtime: releaseSudog with non-nil gp.param")
diff --git a/src/runtime/select.go b/src/runtime/select.go
index efe68c1f5c..f735a71e2f 100644
--- a/src/runtime/select.go
+++ b/src/runtime/select.go
@@ -404,6 +404,7 @@ loop:
 			}
 		}
 		sgnext = sglist.waitlink
+		sglist.waitlink = nil
 		releaseSudog(sglist)
 		sglist = sgnext
 	}
@@ -641,6 +642,7 @@ func (q *waitq) dequeueSudoG(s *sudog) {
 			if q.last == sgp {
 				q.last = prevsgp
 			}
+			s.next = nil
 			return
 		}
 		l = &sgp.next
diff --git a/src/runtime/sema.go b/src/runtime/sema.go
index d2a028c01b..26dbd30ea3 100644
--- a/src/runtime/sema.go
+++ b/src/runtime/sema.go
@@ -201,6 +201,7 @@ func syncsemacquire(s *syncSema) {
 		}
 		unlock(&s.lock)
 		if wake != nil {
+			wake.next = nil
 			goready(wake.g)
 		}
 	} else {
@@ -242,6 +243,7 @@ func syncsemrelease(s *syncSema, n uint32) {
 		if wake.releasetime != 0 {
 			wake.releasetime = cputicks()
 		}
+		wake.next = nil
 		goready(wake.g)
 		n--
 	}