mm: don't pass "enum lru_list" to trace_mm_lru_insertion()

The parameter is redundant in the sense that it can be extracted
from the "struct page" parameter by page_lru() correctly.

Link: https://lore.kernel.org/linux-mm/20201207220949.830352-5-yuzhao@google.com/
Signed-off-by: Yu Zhao <yuzhao@google.com>
Reviewed-by: Alex Shi <alex.shi@linux.alibaba.com>

include/trace/events/pagemap.h

@@ -27,24 +27,21 @@
 
 TRACE_EVENT(mm_lru_insertion,
 
-	TP_PROTO(
-		struct page *page,
-		int lru
-	),
+	TP_PROTO(struct page *page),
 
-	TP_ARGS(page, lru),
+	TP_ARGS(page),
 
 	TP_STRUCT__entry(
 		__field(struct page *,	page	)
 		__field(unsigned long,	pfn	)
-		__field(int,		lru	)
+		__field(enum lru_list,	lru	)
 		__field(unsigned long,	flags	)
 	),
 
 	TP_fast_assign(
 		__entry->page	= page;
 		__entry->pfn	= page_to_pfn(page);
-		__entry->lru	= lru;
+		__entry->lru	= page_lru(page);
 		__entry->flags	= trace_pagemap_flags(page);
 	),
 

mm/swap.c

@@ -957,7 +957,6 @@ EXPORT_SYMBOL(__pagevec_release);
 
 static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec)
 {
-	enum lru_list lru;
 	int was_unevictable = TestClearPageUnevictable(page);
 	int nr_pages = thp_nr_pages(page);
 
@@ -993,19 +992,17 @@ static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec)
 	smp_mb__after_atomic();
 
 	if (page_evictable(page)) {
-		lru = page_lru(page);
 		if (was_unevictable)
 			__count_vm_events(UNEVICTABLE_PGRESCUED, nr_pages);
 	} else {
-		lru = LRU_UNEVICTABLE;
 		ClearPageActive(page);
 		SetPageUnevictable(page);
 		if (!was_unevictable)
 			__count_vm_events(UNEVICTABLE_PGCULLED, nr_pages);
 	}
 
 	add_page_to_lru_list(page, lruvec);
-	trace_mm_lru_insertion(page, lru);
+	trace_mm_lru_insertion(page);
 }
 
 /*