mm/page_alloc: update PGFREE outside the zone lock in __free_pages_ok

VM events do not need explicit protection by disabling IRQs so update the
counter with IRQs enabled in __free_pages_ok.

Link: https://lkml.kernel.org/r/20210512095458.30632-10-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/page_alloc.c

@@ -1600,13 +1600,14 @@ static void __free_pages_ok(struct page *page, unsigned int order,
 	migratetype = get_pfnblock_migratetype(page, pfn);
 
 	spin_lock_irqsave(&zone->lock, flags);
-	__count_vm_events(PGFREE, 1 << order);
 	if (unlikely(has_isolate_pageblock(zone) ||
 		is_migrate_isolate(migratetype))) {
 		migratetype = get_pfnblock_migratetype(page, pfn);
 	}
 	__free_one_page(page, pfn, zone, order, migratetype, fpi_flags);
 	spin_unlock_irqrestore(&zone->lock, flags);
+
+	__count_vm_events(PGFREE, 1 << order);
 }
 
 void __free_pages_core(struct page *page, unsigned int order)