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Commit 5a883813 authored by Minchan Kim's avatar Minchan Kim Committed by Linus Torvalds
Browse files

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: default avatarWen Congyang <wency@cn.fujitsu.com>
Signed-off-by: default avatarMinchan Kim <minchan@kernel.org>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 08270807

include/linux/vmstat.h

+4 −0
Original line number Diff line number Diff line
@@ -198,6 +198,8 @@ extern void __dec_zone_state(struct zone *, enum zone_stat_item); 
void refresh_cpu_vm_stats(int);

void refresh_zone_stat_thresholds(void);



void drain_zonestat(struct zone *zone, struct per_cpu_pageset *);



int calculate_pressure_threshold(struct zone *zone);

int calculate_normal_threshold(struct zone *zone);

void set_pgdat_percpu_threshold(pg_data_t *pgdat,
@@ -251,6 +253,8 @@ static inline void __dec_zone_page_state(struct page *page, 
static inline void refresh_cpu_vm_stats(int cpu) { }

static inline void refresh_zone_stat_thresholds(void) { }



static inline void drain_zonestat(struct zone *zone,

			struct per_cpu_pageset *pset) { }

#endif		/* CONFIG_SMP */



static inline void __mod_zone_freepage_state(struct zone *zone, int nr_pages,

mm/page_alloc.c

+7 −0
Original line number Diff line number Diff line
@@ -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;

	}

mm/vmstat.c

+12 −0
Original line number Diff line number Diff line
@@ -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