}

	gp.m.locks--
	return npages
}

// isSweepDone reports whether all spans are swept.
//
// Note that this condition may transition from false to true at any
// time as the sweeper runs. It may transition from true to false if a
// GC runs; to prevent that the caller must be non-preemptible or must
// somehow block GC progress.
func isSweepDone() bool {
	return sweep.active.isDone()
}

//
// This can be called any time. If GC is the in the middle of a
// concurrent phase, it will adjust the pacing of that phase.
//
// isSweepDone should be the result of calling isSweepDone(),
// unless we're testing or we know we're executing during a GC cycle.
//
// This depends on gcPercent, gcController.heapMarked, and
// gcController.heapLive. These must be up to date.
//

	//
	// First, wait for sweeping to finish. (We know there are no
	// more spans on the sweep queue, but we may be concurrently
	// sweeping spans, so we have to wait.)
	for work.cycles.Load() == n+1 && !isSweepDone() {
		Gosched()
	}

	// Now we're really done with sweeping, so we can publish the
	// stable heap profile. Only do this if we haven't already hit
	// another mark termination.
	mp := acquirem()

	// 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)
		}
		s = h.allocSpan(npages, spanAllocHeap, spanclass)
	})
	return s
}

// allocManual allocates a manually-managed span of npage pages.