From 5a883813845a2bb5ed2bd8c9240736c0740b156f Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Mon, 8 Oct 2012 16:33:39 -0700 Subject: 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 Signed-off-by: Minchan Kim Cc: Kamezawa Hiroyuki Cc: Yasuaki Ishimatsu Cc: KOSAKI Motohiro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'mm/page_alloc.c') diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 9b8e6243a524..5485f0ef4ec3 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5916,6 +5916,7 @@ static int __meminit __zone_pcp_update(void *data) 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 __meminit zone_pcp_update(struct zone *zone) 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; } -- cgit v1.2.3