Vlastimil Babka noted that __setup_per_zone_wmarks updating
pcp->high did not protect watermark-related sysctl handlers from a
parallel memory hotplug operations. This patch moves the PCP update to
setup_per_zone_wmarks and updates the PCP high value while protected by
the pcp_batch_high_lock mutex. As a side-effect, the zone_pcp_update calls
during memory hotplug operations becomes redundant and can be removed.
This is a fix to the mmotm patch
mm-page_alloc-disassociate-the-pcp-high-from-pcp-batch.patch.
It'll cause a conflict with
mm-page_alloc-adjust-pcp-high-after-cpu-hotplug-events.patch
but the resolution is simple as the zone_pcp_update callers in
setup_per_zone_wmarks no longer exist.
Signed-off-by: Mel Gorman <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
---
mm/memory_hotplug.c | 6 +++---
mm/page_alloc.c | 14 ++++++++------
2 files changed, 11 insertions(+), 9 deletions(-)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 70620d0dd923..974a565797d8 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -961,7 +961,6 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, struct zone *z
node_states_set_node(nid, &arg);
if (need_zonelists_rebuild)
build_all_zonelists(NULL);
- zone_pcp_update(zone);
/* Basic onlining is complete, allow allocation of onlined pages. */
undo_isolate_page_range(pfn, pfn + nr_pages, MIGRATE_MOVABLE);
@@ -974,6 +973,7 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, struct zone *z
*/
shuffle_zone(zone);
+ /* reinitialise watermarks and update pcp limits */
init_per_zone_wmark_min();
kswapd_run(nid);
@@ -1829,13 +1829,13 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages)
adjust_managed_page_count(pfn_to_page(start_pfn), -nr_pages);
adjust_present_page_count(zone, -nr_pages);
+ /* reinitialise watermarks and update pcp limits */
init_per_zone_wmark_min();
if (!populated_zone(zone)) {
zone_pcp_reset(zone);
build_all_zonelists(NULL);
- } else
- zone_pcp_update(zone);
+ }
node_states_clear_node(node, &arg);
if (arg.status_change_nid >= 0) {
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index c0536e5d088a..b686344e3889 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8188,12 +8188,6 @@ static void __setup_per_zone_wmarks(void)
zone->_watermark[WMARK_LOW] = min_wmark_pages(zone) + tmp;
zone->_watermark[WMARK_HIGH] = min_wmark_pages(zone) + tmp * 2;
- /*
- * The watermark size have changed so update the pcpu batch
- * and high limits or the limits may be inappropriate.
- */
- zone_set_pageset_high_and_batch(zone);
-
spin_unlock_irqrestore(&zone->lock, flags);
}
@@ -8210,11 +8204,19 @@ static void __setup_per_zone_wmarks(void)
*/
void setup_per_zone_wmarks(void)
{
+ struct zone *zone;
static DEFINE_SPINLOCK(lock);
spin_lock(&lock);
__setup_per_zone_wmarks();
spin_unlock(&lock);
+
+ /*
+ * The watermark size have changed so update the pcpu batch
+ * and high limits or the limits may be inappropriate.
+ */
+ for_each_zone(zone)
+ zone_pcp_update(zone);
}
/*
--
Mel Gorman
SUSE Labs