memory-hotplug: fix zone stat mismatch
During memory-hotplug, I found NR_ISOLATED_[ANON|FILE] are increasing,
causing the kernel to hang. When the system doesn't have enough free
pages, it enters reclaim but never reclaim any pages due to
too_many_isolated()==true and loops forever.
The cause is that when we do memory-hotadd after memory-remove,
__zone_pcp_update() clears a zone's ZONE_STAT_ITEMS in setup_pageset()
although the vm_stat_diff of all CPUs still have values.
In addtion, when we offline all pages of the zone, we reset them in
zone_pcp_reset without draining so we loss some zone stat item.
Reviewed-by: Wen Congyang <[email protected]>
Signed-off-by: Minchan Kim <[email protected]>
Cc: Kamezawa Hiroyuki <[email protected]>
Cc: Yasuaki Ishimatsu <[email protected]>
Cc: KOSAKI Motohiro <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 9b8e624..5485f0e 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5916,6 +5916,7 @@
local_irq_save(flags);
if (pcp->count > 0)
free_pcppages_bulk(zone, pcp->count, pcp);
+ drain_zonestat(zone, pset);
setup_pageset(pset, batch);
local_irq_restore(flags);
}
@@ -5932,10 +5933,16 @@
void zone_pcp_reset(struct zone *zone)
{
unsigned long flags;
+ int cpu;
+ struct per_cpu_pageset *pset;
/* avoid races with drain_pages() */
local_irq_save(flags);
if (zone->pageset != &boot_pageset) {
+ for_each_online_cpu(cpu) {
+ pset = per_cpu_ptr(zone->pageset, cpu);
+ drain_zonestat(zone, pset);
+ }
free_percpu(zone->pageset);
zone->pageset = &boot_pageset;
}
