BACKPORT: mm: add __clear_page_lru_flags() to replace page_off_lru()

Similar to page_off_lru(), the new function does non-atomic clearing
of PageLRU() in addition to PageActive() and PageUnevictable(), on a
page that has no references left.

If PageActive() and PageUnevictable() are both set, refuse to clear
either and leave them to bad_page(). This is a behavior change that
is meant to help debug.
Moto-CRs-Fixed:(CR)

Link: https://lore.kernel.org/linux-mm/20201207220949.830352-7-yuzhao@google.com/
Link: https://lkml.kernel.org/r/20210122220600.906146-7-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit 875601796267214f286d3581fe74f2805d060fe8)
Bug: 228114874
Change-Id: I0290916fa08277c50e228a8d3f39af67d62ff9d0
Reviewed-on: https://gerrit.mot.com/2268692
SME-Granted: SME Approvals Granted
SLTApproved: Slta Waiver
Tested-by: Jira Key
Reviewed-by: Xiangpo Zhao <zhaoxp3@motorola.com>
Submit-Approved: Jira Key

include/linux/mm_inline.h

@@ -60,27 +60,19 @@ static inline enum lru_list page_lru_base_type(struct page *page)
 }
 
 /**
- * page_off_lru - which LRU list was page on? clearing its lru flags.
- * @page: the page to test
- *
- * Returns the LRU list a page was on, as an index into the array of LRU
- * lists; and clears its Unevictable or Active flags, ready for freeing.
+ * __clear_page_lru_flags - clear page lru flags before releasing a page
+ * @page: the page that was on lru and now has a zero reference
  */
-static __always_inline enum lru_list page_off_lru(struct page *page)
+static __always_inline void __clear_page_lru_flags(struct page *page)
 {
-	enum lru_list lru;
+	__ClearPageLRU(page);
 
-	if (PageUnevictable(page)) {
-		__ClearPageUnevictable(page);
-		lru = LRU_UNEVICTABLE;
-	} else {
-		lru = page_lru_base_type(page);
-		if (PageActive(page)) {
-			__ClearPageActive(page);
-			lru += LRU_ACTIVE;
-		}
-	}
-	return lru;
+	/* this shouldn't happen, so leave the flags to bad_page() */
+	if (PageActive(page) && PageUnevictable(page))
+		return;
+
+	__ClearPageActive(page);
+	__ClearPageUnevictable(page);
 }
 
 /**

mm/swap.c

@@ -66,9 +66,8 @@ static void __page_cache_release(struct page *page)
 		spin_lock_irqsave(zone_lru_lock(zone), flags);
 		lruvec = mem_cgroup_page_lruvec(page, zone->zone_pgdat);
 		VM_BUG_ON_PAGE(!PageLRU(page), page);
-		__ClearPageLRU(page);
 		del_page_from_lru_list(page, lruvec);
-		page_off_lru(page);
+		__clear_page_lru_flags(page);
 		spin_unlock_irqrestore(zone_lru_lock(zone), flags);
 	}
 	__ClearPageWaiters(page);
@@ -778,9 +777,8 @@ void release_pages(struct page **pages, int nr)
 
 			lruvec = mem_cgroup_page_lruvec(page, locked_pgdat);
 			VM_BUG_ON_PAGE(!PageLRU(page), page);
-			__ClearPageLRU(page);
 			del_page_from_lru_list(page, lruvec);
-			page_off_lru(page);
+			__clear_page_lru_flags(page);
 		}
 
 		__ClearPageWaiters(page);

mm/vmscan.c

@@ -1919,9 +1919,8 @@ putback_inactive_pages(struct lruvec *lruvec, struct list_head *page_list)
 			reclaim_stat->recent_rotated[file] += numpages;
 		}
 		if (put_page_testzero(page)) {
-			__ClearPageLRU(page);
 			del_page_from_lru_list(page, lruvec);
-			__ClearPageActive(page);
+			__clear_page_lru_flags(page);
 
 			if (unlikely(PageCompound(page))) {
 				spin_unlock_irq(&pgdat->lru_lock);
@@ -2106,9 +2105,8 @@ static unsigned move_active_pages_to_lru(struct lruvec *lruvec,
 		add_page_to_lru_list(page, lruvec);
 
 		if (put_page_testzero(page)) {
-			__ClearPageLRU(page);
 			del_page_from_lru_list(page, lruvec);
-			__ClearPageActive(page);
+			__clear_page_lru_flags(page);
 
 			if (unlikely(PageCompound(page))) {
 				spin_unlock_irq(&pgdat->lru_lock);