[PATCH v4 1/3] mm/free_pcppages_bulk: update pcp->count inside

From: Aaron Lu
Date: Thu Mar 01 2018 - 01:27:58 EST


Matthew Wilcox found that all callers of free_pcppages_bulk() currently
update pcp->count immediately after so it's natural to do it inside
free_pcppages_bulk().

No functionality or performance change is expected from this patch.

Suggested-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Signed-off-by: Aaron Lu <aaron.lu@xxxxxxxxx>
---
mm/page_alloc.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index cb416723538f..faa33eac1635 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1148,6 +1148,7 @@ static void free_pcppages_bulk(struct zone *zone, int count,
page = list_last_entry(list, struct page, lru);
/* must delete as __free_one_page list manipulates */
list_del(&page->lru);
+ pcp->count--;

mt = get_pcppage_migratetype(page);
/* MIGRATE_ISOLATE page should not go to pcplists */
@@ -2416,10 +2417,8 @@ void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp)
local_irq_save(flags);
batch = READ_ONCE(pcp->batch);
to_drain = min(pcp->count, batch);
- if (to_drain > 0) {
+ if (to_drain > 0)
free_pcppages_bulk(zone, to_drain, pcp);
- pcp->count -= to_drain;
- }
local_irq_restore(flags);
}
#endif
@@ -2441,10 +2440,8 @@ static void drain_pages_zone(unsigned int cpu, struct zone *zone)
pset = per_cpu_ptr(zone->pageset, cpu);

pcp = &pset->pcp;
- if (pcp->count) {
+ if (pcp->count)
free_pcppages_bulk(zone, pcp->count, pcp);
- pcp->count = 0;
- }
local_irq_restore(flags);
}

@@ -2668,7 +2665,6 @@ static void free_unref_page_commit(struct page *page, unsigned long pfn)
if (pcp->count >= pcp->high) {
unsigned long batch = READ_ONCE(pcp->batch);
free_pcppages_bulk(zone, batch, pcp);
- pcp->count -= batch;
}
}

--
2.14.3