On Fri, May 19 2023 at 20:03, Baoquan He wrote: > @@ -2245,6 +2260,9 @@ static void _vm_unmap_aliases(unsigned long start, unsigned long end, int flush) > > might_sleep(); > > + mutex_lock(&vmap_purge_lock); > + purge_fragmented_blocks_allcpus(); > + > for_each_possible_cpu(cpu) { That still does TWO iterations over all possible CPUs, while this really could be one.