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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 /include/linux/mmzone.h
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 'include/linux/mmzone.h')
-rw-r--r--include/linux/mmzone.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index fc4b5cdb6c2d..cc4a507d7ca4 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -636,8 +636,8 @@ typedef struct pglist_data {
#endif
#if defined(CONFIG_MEMORY_HOTPLUG) || defined(CONFIG_DEFERRED_STRUCT_PAGE_INIT)
/*
- * Must be held any time you expect node_start_pfn, node_present_pages
- * or node_spanned_pages stay constant.
+ * Must be held any time you expect node_start_pfn,
+ * node_present_pages, node_spanned_pages or nr_zones to stay constant.
*
* pgdat_resize_lock() and pgdat_resize_unlock() are provided to
* manipulate node_size_lock without checking for CONFIG_MEMORY_HOTPLUG