s390/kasan: optimize kasan vmemmap allocation

Kasan implementation now supports memory hotplug operations. For that
reason regions of initially standby memory are now skipped from
shadow mapping and are mapped/unmapped dynamically upon bringing
memory online/offline.
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/mm/kasan_init.c

@@ -331,7 +331,8 @@ void __init kasan_early_init(void)
 	kasan_early_vmemmap_populate(__sha(0), __sha(memsize), POPULATE_MAP);
 	if (IS_ENABLED(CONFIG_MODULES))
 		untracked_mem_end = vmax - MODULES_LEN;
-	kasan_early_vmemmap_populate(__sha(memsize), __sha(untracked_mem_end),
+	kasan_early_vmemmap_populate(__sha(max_physmem_end),
+				     __sha(untracked_mem_end),
 				     POPULATE_ZERO_SHADOW);
 	/* memory allocated for identity mapping structs will be freed later */
 	pgalloc_freeable = pgalloc_pos;