On 05/24/2017 02:24 PM, Michal Hocko wrote: > From: Michal Hocko <[email protected]> > > 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")
That's the same commit as above... one of them should be different? > 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 <[email protected]> - > 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 <[email protected]> - Some editing issue? Otherwise makes sense to me. Acked-by: Vlastimil Babka <[email protected]> > --- > 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); >
