The patch titled
Subject: mm, hotplug: move init_currently_empty_zone() under zone_span_lock protection
has been added to the -mm tree. Its filename is
mm-hotplug-move-init_currently_empty_zone-under-zone_span_lock-protection.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-hotplug-move-init_currently_empty_zone-under-zone_span_lock-protection.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-hotplug-move-init_currently_empty_zone-under-zone_span_lock-protection.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Wei Yang <richard.weiyang@xxxxxxxxx>
Subject: 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@xxxxxxxxx
Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mmzone.h | 7 ++++---
mm/memory_hotplug.c | 5 ++---
2 files changed, 6 insertions(+), 6 deletions(-)
--- a/include/linux/mmzone.h~mm-hotplug-move-init_currently_empty_zone-under-zone_span_lock-protection
+++ a/include/linux/mmzone.h
@@ -636,9 +636,10 @@ 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. Holding this will also
- * guarantee that any pfn_valid() stays that way.
+ * Must be held any time you expect node_start_pfn,
+ * node_present_pages, node_spanned_pages or nr_zones stay constant.
+ * Holding this will also guarantee that any pfn_valid() stays that
+ * way.
*
* pgdat_resize_lock() and pgdat_resize_unlock() are provided to
* manipulate node_size_lock without checking for CONFIG_MEMORY_HOTPLUG
--- a/mm/memory_hotplug.c~mm-hotplug-move-init_currently_empty_zone-under-zone_span_lock-protection
+++ a/mm/memory_hotplug.c
@@ -718,14 +718,13 @@ void __ref move_pfn_range_to_zone(struct
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);
_
Patches currently in -mm which might be from richard.weiyang@xxxxxxxxx are
mm-slub-remove-validation-on-cpu_slab-in-__flush_cpu_slab.patch
mm-slub-page-is-always-non-null-for-node_match.patch
mm-slub-record-final-state-of-slub-action-in-deactivate_slab.patch
mm-slub-improve-performance-by-skipping-checked-node-in-get_any_partial.patch
mm-remove-reset-of-pcp-counter-in-pageset_init.patch
vmscan-return-node_reclaim_noscan-in-node_reclaim-when-config_numa-is-n.patch
drivers-base-memoryc-remove-an-unnecessary-check-on-nr_mem_sections.patch
mm-check-nr_initialised-with-pages_per_section-directly-in-defer_init.patch
mm-sparse-drop-pgdat_resize_lock-in-sparse_add-remove_one_section.patch
mm-hotplug-move-init_currently_empty_zone-under-zone_span_lock-protection.patch
