[040/165] mm, memory_hotplug: update pcp lists everytime onlining a memory block

Commit Message

Andrew Morton Aug. 12, 2020, 1:32 a.m. UTC

From: Charan Teja Reddy <[e-mail]>
Subject: mm, memory_hotplug: update pcp lists everytime onlining a memory block

When onlining a first memory block in a zone, pcp lists are not updated
thus pcp struct will have the default setting of ->high = 0,->batch = 1.

This means till the second memory block in a zone(if it have) is onlined
the pcp lists of this zone will not contain any pages because pcp's
->count is always greater than ->high thus free_pcppages_bulk() is called
to free batch size(=1) pages every time system wants to add a page to the
pcp list through free_unref_page().

To put this in a word, system is not using benefits offered by the pcp
lists when there is a single onlineable memory block in a zone.  Correct
this by always updating the pcp lists when memory block is onlined.

Link: http://lkml.kernel.org/r/[e-mail]
Fixes: 1f522509c77a ("mem-hotplug: avoid multiple zones sharing same boot strapping boot_pageset")
Signed-off-by: Charan Teja Reddy <[e-mail]>
Reviewed-by: David Hildenbrand <[e-mail]>
Acked-by: Vlastimil Babka <[e-mail]>
Acked-by: Michal Hocko <[e-mail]>
Cc: Vinayak Menon <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/memory_hotplug.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

Patch

--- a/mm/memory_hotplug.c~mm-memory_hotplug-update-pcp-lists-everytime-onlining-a-memory-block
+++ a/mm/memory_hotplug.c
@@ -854,8 +854,7 @@  int __ref online_pages(unsigned long pfn
 	node_states_set_node(nid, &arg);
 	if (need_zonelists_rebuild)
 		build_all_zonelists(NULL);
-	else
-		zone_pcp_update(zone);
+	zone_pcp_update(zone);
 
 	init_per_zone_wmark_min();