mm/memcg: Convert memcg_check_events to take a node ID

memcg_check_events only uses the page's nid, so call page_to_nid in the
callers to make the interface easier to understand.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>

mm/memcontrol.c

@@ -819,7 +819,7 @@ static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
  * Check events in order.
  *
  */
-static void memcg_check_events(struct mem_cgroup *memcg, struct page *page)
+static void memcg_check_events(struct mem_cgroup *memcg, int nid)
 {
 	/* threshold event is triggered in finer grain than soft limit */
 	if (unlikely(mem_cgroup_event_ratelimit(memcg,
@@ -830,7 +830,7 @@ static void memcg_check_events(struct mem_cgroup *memcg, struct page *page)
 						MEM_CGROUP_TARGET_SOFTLIMIT);
 		mem_cgroup_threshold(memcg);
 		if (unlikely(do_softlimit))
-			mem_cgroup_update_tree(memcg, page_to_nid(page));
+			mem_cgroup_update_tree(memcg, nid);
 	}
 }
 
@@ -5555,7 +5555,7 @@ static int mem_cgroup_move_account(struct page *page,
 	struct lruvec *from_vec, *to_vec;
 	struct pglist_data *pgdat;
 	unsigned int nr_pages = compound ? thp_nr_pages(page) : 1;
-	int ret;
+	int nid, ret;
 
 	VM_BUG_ON(from == to);
 	VM_BUG_ON_PAGE(PageLRU(page), page);
@@ -5644,12 +5644,13 @@ static int mem_cgroup_move_account(struct page *page,
 	__unlock_page_memcg(from);
 
 	ret = 0;
+	nid = page_to_nid(page);
 
 	local_irq_disable();
 	mem_cgroup_charge_statistics(to, nr_pages);
-	memcg_check_events(to, page);
+	memcg_check_events(to, nid);
 	mem_cgroup_charge_statistics(from, -nr_pages);
-	memcg_check_events(from, page);
+	memcg_check_events(from, nid);
 	local_irq_enable();
 out_unlock:
 	unlock_page(page);
@@ -6671,7 +6672,7 @@ static int charge_memcg(struct page *page, struct mem_cgroup *memcg, gfp_t gfp)
 
 	local_irq_disable();
 	mem_cgroup_charge_statistics(memcg, nr_pages);
-	memcg_check_events(memcg, page);
+	memcg_check_events(memcg, page_to_nid(page));
 	local_irq_enable();
 out:
 	return ret;
@@ -6777,7 +6778,7 @@ struct uncharge_gather {
 	unsigned long nr_memory;
 	unsigned long pgpgout;
 	unsigned long nr_kmem;
-	struct page *dummy_page;
+	int nid;
 };
 
 static inline void uncharge_gather_clear(struct uncharge_gather *ug)
@@ -6801,7 +6802,7 @@ static void uncharge_batch(const struct uncharge_gather *ug)
 	local_irq_save(flags);
 	__count_memcg_events(ug->memcg, PGPGOUT, ug->pgpgout);
 	__this_cpu_add(ug->memcg->vmstats_percpu->nr_page_events, ug->nr_memory);
-	memcg_check_events(ug->memcg, ug->dummy_page);
+	memcg_check_events(ug->memcg, ug->nid);
 	local_irq_restore(flags);
 
 	/* drop reference from uncharge_page */
@@ -6842,7 +6843,7 @@ static void uncharge_page(struct page *page, struct uncharge_gather *ug)
 			uncharge_gather_clear(ug);
 		}
 		ug->memcg = memcg;
-		ug->dummy_page = page;
+		ug->nid = page_to_nid(page);
 
 		/* pairs with css_put in uncharge_batch */
 		css_get(&memcg->css);
@@ -6954,7 +6955,7 @@ void mem_cgroup_migrate(struct page *oldpage, struct page *newpage)
 
 	local_irq_save(flags);
 	mem_cgroup_charge_statistics(memcg, nr_pages);
-	memcg_check_events(memcg, newpage);
+	memcg_check_events(memcg, page_to_nid(newpage));
 	local_irq_restore(flags);
 }
 
@@ -7182,7 +7183,7 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
 	 */
 	VM_BUG_ON(!irqs_disabled());
 	mem_cgroup_charge_statistics(memcg, -nr_entries);
-	memcg_check_events(memcg, page);
+	memcg_check_events(memcg, page_to_nid(page));
 
 	css_put(&memcg->css);
 }