// nothing to do, silently ignore it.
		return false
	}

	// ensure that the span is swept, b/c sweeping accesses the specials list
	// w/o locks.
	mp := acquirem()
	span.ensureSwept()
	KeepAlive(ptr) // make sure ptr is still alive after span is swept

	objIndex := span.objIndex(uintptr(ptr))

	lock(&span.speciallock) // guard against concurrent calls of setPinned on same span

var dumphdr = []byte("go1.7 heap dump\n")

func mdump(m *MemStats) {
	assertWorldStopped()

	// make sure we're done sweeping
	for _, s := range mheap_.allspans {
		if s.state.get() == mSpanInUse {
			s.ensureSwept()
		}
	}
	memclrNoHeapPointers(unsafe.Pointer(&typecache), unsafe.Sizeof(typecache))
	dwrite(unsafe.Pointer(&dumphdr[0]), uintptr(len(dumphdr)))
	dumpparams()
	dumpitabs()
	dumpobjs()
	dumpgs()

// Returns only when span s has been swept.
//
//go:nowritebarrier
func (s *mspan) ensureSwept() {
	// Caller must disable preemption.
	// Otherwise when this function returns the span can become unswept again
	// (if GC is triggered on another goroutine).
	gp := getg()
	if gp.m.locks == 0 && gp.m.mallocing == 0 && gp != gp.m.g0 {
		throw("mspan.ensureSwept: m is not locked")
	}

	}

	// Ensure that the span is swept.
	// Sweeping accesses the specials list w/o locks, so we have
	// to synchronize with it. And it's just much safer.
	mp := acquirem()
	span.ensureSwept()

	offset := uintptr(p) - span.base()
	kind := s.kind

	lock(&span.speciallock)

	// Find splice point, check for existing record.
	iter, exists := span.specialFindSplicePoint(offset, kind)