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authorWei Yang <richard.weiyang@gmail.com>2018-12-28 00:37:10 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-12-28 12:11:49 -0800
commitfa004ab7365ffa1e17e6b267d64798afccb94946 (patch)
treea0b1c60eac4511b3c4813da3865f683e82eaa7c4 /mm
parent4e0d2e7ef14d9e1c900dac909db45263822b824f (diff)
mm, hotplug: move init_currently_empty_zone() under zone_span_lock protection
During online_pages phase, pgdat->nr_zones will be updated in case this zone is empty. Currently the online_pages phase is protected by the global locks (device_device_hotplug_lock and mem_hotplug_lock), which ensures there is no contention during the update of nr_zones. These global locks introduces scalability issues (especially the second one), which slow down code relying on get_online_mems(). This is also a preparation for not having to rely on get_online_mems() but instead some more fine grained locks. The patch moves init_currently_empty_zone under both zone_span_writelock and pgdat_resize_lock because both the pgdat state is changed (nr_zones) and the zone's start_pfn. Also this patch changes the documentation of node_size_lock to include the protection of nr_zones. Link: http://lkml.kernel.org/r/20181203205016.14123-1-richard.weiyang@gmail.com Signed-off-by: Wei Yang <richard.weiyang@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/memory_hotplug.c5
1 files changed, 2 insertions, 3 deletions
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 5f15f9c04c4a..c2b34ec602ee 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -743,14 +743,13 @@ void __ref move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn,
int nid = pgdat->node_id;
unsigned long flags;
- if (zone_is_empty(zone))
- init_currently_empty_zone(zone, start_pfn, nr_pages);
-
clear_zone_contiguous(zone);
/* TODO Huh pgdat is irqsave while zone is not. It used to be like that before */
pgdat_resize_lock(pgdat, &flags);
zone_span_writelock(zone);
+ if (zone_is_empty(zone))
+ init_currently_empty_zone(zone, start_pfn, nr_pages);
resize_zone_range(zone, start_pfn, nr_pages);
zone_span_writeunlock(zone);
resize_pgdat_range(pgdat, start_pfn, nr_pages);