From: Michal Hocko <mhocko@xxxxxxxx> 74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL memory") has added can_offline_normal which checks the amount of memory in !movable zones as long as CONFIG_MOVABLE_NODE is disable. It disallows to offline memory if there is nothing left with a justification that "memory-management acts bad when we have nodes which is online but don't have any normal memory". 74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL memory") has introduced a restriction that every numa node has to have at least some memory in !movable zones before a first movable memory can be onlined if !CONFIG_MOVABLE_NODE with the same justification While it is true that not having _any_ memory for kernel allocations on a NUMA node is far from great and such a node would be quite subotimal because all kernel allocations will have to fallback to another NUMA node but there is no reason to disallow such a configuration in principle. Besides that there is not really a big difference to have one memblock for ZONE_NORMAL available or none. With 128MB size memblocks the system might trash on the kernel allocations requests anyway. It is really hard to draw a line on how much normal memory is really sufficient so we have to rely on administrator to configure system sanely therefore drop the artificial restriction and remove can_offline_normal and can_online_high_movable altogether. Signed-off-by: Michal Hocko <mhocko@xxxxxxxx> mm, memory_hotplug: drop can_online_high_movable because "memory-management acts bad when we have nodes which is online but don't have any normal memory. Signed-off-by: Michal Hocko <mhocko@xxxxxxxx> --- mm/memory_hotplug.c | 58 ----------------------------------------------------- 1 file changed, 58 deletions(-) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 599c675ad538..10052c2fd400 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -763,23 +763,6 @@ static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages, return 0; } -#ifdef CONFIG_MOVABLE_NODE -/* - * When CONFIG_MOVABLE_NODE, we permit onlining of a node which doesn't have - * normal memory. - */ -static bool can_online_high_movable(int nid) -{ - return true; -} -#else /* CONFIG_MOVABLE_NODE */ -/* ensure every online node has NORMAL memory */ -static bool can_online_high_movable(int nid) -{ - return node_state(nid, N_NORMAL_MEMORY); -} -#endif /* CONFIG_MOVABLE_NODE */ - /* check which state of node_states will be changed when online memory */ static void node_states_check_changes_online(unsigned long nr_pages, struct zone *zone, struct memory_notify *arg) @@ -979,9 +962,6 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ if (!allow_online_pfn_range(nid, pfn, nr_pages, online_type)) return -EINVAL; - if (online_type == MMOP_ONLINE_MOVABLE && !can_online_high_movable(nid)) - return -EINVAL; - /* associate pfn range with the zone */ zone = move_pfn_range(online_type, nid, pfn, nr_pages); @@ -1579,41 +1559,6 @@ check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn) return offlined; } -#ifdef CONFIG_MOVABLE_NODE -/* - * When CONFIG_MOVABLE_NODE, we permit offlining of a node which doesn't have - * normal memory. - */ -static bool can_offline_normal(struct zone *zone, unsigned long nr_pages) -{ - return true; -} -#else /* CONFIG_MOVABLE_NODE */ -/* ensure the node has NORMAL memory if it is still online */ -static bool can_offline_normal(struct zone *zone, unsigned long nr_pages) -{ - struct pglist_data *pgdat = zone->zone_pgdat; - unsigned long present_pages = 0; - enum zone_type zt; - - for (zt = 0; zt <= ZONE_NORMAL; zt++) - present_pages += pgdat->node_zones[zt].present_pages; - - if (present_pages > nr_pages) - return true; - - present_pages = 0; - for (; zt <= ZONE_MOVABLE; zt++) - present_pages += pgdat->node_zones[zt].present_pages; - - /* - * we can't offline the last normal memory until all - * higher memory is offlined. - */ - return present_pages == 0; -} -#endif /* CONFIG_MOVABLE_NODE */ - static int __init cmdline_parse_movable_node(char *p) { #ifdef CONFIG_MOVABLE_NODE @@ -1741,9 +1686,6 @@ static int __ref __offline_pages(unsigned long start_pfn, node = zone_to_nid(zone); nr_pages = end_pfn - start_pfn; - if (zone_idx(zone) <= ZONE_NORMAL && !can_offline_normal(zone, nr_pages)) - return -EINVAL; - /* set above range as isolated */ ret = start_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE, true); -- 2.11.0 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>