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/vmstat.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'mm/vmstat.c') diff --git a/mm/vmstat.c b/mm/vmstat.c index 05e3a9913744..2f11309955cc 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -495,6 +495,18 @@ void refresh_cpu_vm_stats(int cpu) atomic_long_add(global_diff[i], &vm_stat[i]); } +void drain_zonestat(struct zone *zone, struct per_cpu_pageset *pset) +{ + int i; + + for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) + if (pset->vm_stat_diff[i]) { + int v = pset->vm_stat_diff[i]; + pset->vm_stat_diff[i] = 0; + atomic_long_add(v, &zone->vm_stat[i]); + atomic_long_add(v, &vm_stat[i]); + } +} #endif #ifdef CONFIG_NUMA -- cgit v1.2.3-55-g7522