func freemcache(c *mcache) {
	systemstack(func() {
		c.releaseAll()
		stackcache_clear(c)

		// NOTE(rsc,rlh): If gcworkbuffree comes back, we need to coordinate
		// with the stealing of gcworkbufs during garbage collection to avoid
		// a race where the workbuf is double-freed.
		// gcworkbuffree(c.gcworkbuf)

		lock(&mheap_.lock)
		mheap_.cachealloc.free(unsafe.Pointer(c))
		unlock(&mheap_.lock)
	})
}