work.mode = mode

	now := nanotime()
	work.tSweepTerm = now
	var stw worldStop
	systemstack(func() {
		stw = stopTheWorldWithSema(stwGCSweepTerm)
	})

	// Accumulate fine-grained stopping time.
	work.cpuStats.accumulateGCPauseTime(stw.stoppingCPUTime, 1)

	// Finish sweep before we start concurrent scan.
	systemstack(func() {
		finishsweep_m()
	})

	// the profiler locks. This reduces potential contention and chances of
	// deadlocks. Since the object must be alive during the call to
	// mProf_Malloc, it's fine to do this non-atomically.
	systemstack(func() {
		setprofilebucket(p, b)
	})
}

// Called when freeing a profiled block.
func mProf_Free(b *bucket, size uintptr) {
	index := (mProfCycle.read() + 1) % uint32(len(memRecord{}.future))

		//
		// See the comment on enteredMarkAssistForTracing.
		enteredMarkAssistForTracing = true
	}

	// Perform assist work
	systemstack(func() {
		gcAssistAlloc1(gp, scanWork)
		// The user stack may have moved, so this can't touch
		// anything on it until it returns from systemstack.
	})

	completed := gp.param != nil
	gp.param = nil
	if completed {
		gcMarkDone()
	}

	if gp.gcAssistBytes < 0 {

	RET

// systemstack_switch is a dummy routine that systemstack leaves at the bottom
// of the G stack. We need to distinguish the routine that
// lives at the bottom of the G stack from the one that lives
// at the top of the system stack because the one at the top of
// the system stack terminates the stack walk (see topofstack()).
// The frame layout needs to match systemstack
// so that it can pretend to be systemstack_switch.

			case abi.FuncID_systemstack:
				// systemstack returns normally, so just follow the
				// stack transition.
				if usesLR && funcspdelta(f, frame.pc) == 0 {
					// We're at the function prologue and the stack
					// switch hasn't happened, or epilogue where we're
					// about to return. Just unwind normally.
					// Do this only on LR machines because on x86
					// systemstack doesn't have an SP delta (the CALL

	// Don't do any operations that lock the heap on the G stack.
	// It might trigger stack growth, and the stack growth code needs
	// to be able to allocate heap.
	var s *mspan
	systemstack(func() {
		// To prevent excessive heap growth, before allocating n pages
		// we need to sweep and reclaim at least n pages.
		if !isSweepDone() {
			h.reclaim(npages)
		}

		for i := 0; i < 10; i++ {
			goroutineProf.WriteTo(io.Discard, 1)
		}
	})
}

// TestLabelSystemstack makes sure CPU profiler samples of goroutines running
// on systemstack include the correct pprof labels. See issue #48577
func TestLabelSystemstack(t *testing.T) {
	// Grab and re-set the initial value before continuing to ensure
	// GOGC doesn't actually change following the test.

	c.gcPercent.Store(in)

	return out
}

//go:linkname setGCPercent runtime/debug.setGCPercent
func setGCPercent(in int32) (out int32) {
	// Run on the system stack since we grab the heap lock.
	systemstack(func() {
		lock(&mheap_.lock)
		out = gcController.setGCPercent(in)
		gcControllerCommit()
		unlock(&mheap_.lock)
	})

	// If we just disabled GC, wait for any concurrent GC mark to

func (p *pageAlloc) scavenge(nbytes uintptr, shouldStop func() bool, force bool) uintptr {
	released := uintptr(0)
	for released < nbytes {
		ci, pageIdx := p.scav.index.find(force)
		if ci == 0 {
			break
		}
		systemstack(func() {
			released += p.scavengeOne(ci, pageIdx, nbytes-released)
		})
		if shouldStop != nil && shouldStop() {
			break
		}
	}
	return released
}

//
// Consider marking persistentalloc'd types not in heap by embedding
// runtime/internal/sys.NotInHeap.
func persistentalloc(size, align uintptr, sysStat *sysMemStat) unsafe.Pointer {
	var p *notInHeap
	systemstack(func() {
		p = persistentalloc1(size, align, sysStat)
	})
	return unsafe.Pointer(p)
}

// Must run on system stack because stack growth can (re)invoke it.
// See issue 9174.
//