linux-kernel - [PATCH v2 07/10] mm: VM_BUG

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Date:   Fri, 22 Jan 2021 15:05:57 -0700
From:   Yu Zhao <yuzhao@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Hugh Dickins <hughd@...gle.com>,
        Alex Shi <alex.shi@...ux.alibaba.com>
Cc:     Michal Hocko <mhocko@...nel.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Roman Gushchin <guro@...com>, Vlastimil Babka <vbabka@...e.cz>,
        Matthew Wilcox <willy@...radead.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Yu Zhao <yuzhao@...gle.com>
Subject: [PATCH v2 07/10] mm: VM_BUG_ON lru page flags

Move scattered VM_BUG_ONs to two essential places that cover all
lru list additions and deletions.

Link: https://lore.kernel.org/linux-mm/20201207220949.830352-8-yuzhao@google.com/
Signed-off-by: Yu Zhao <yuzhao@...gle.com>
---
 include/linux/mm_inline.h | 4 ++++
 mm/swap.c                 | 2 --
 mm/vmscan.c               | 1 -
 3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
index ef3fd79222e5..6d907a4dd6ad 100644
--- a/include/linux/mm_inline.h
+++ b/include/linux/mm_inline.h
@@ -66,6 +66,8 @@ static inline enum lru_list page_lru_base_type(struct page *page)
  */
 static __always_inline void __clear_page_lru_flags(struct page *page)
 {
+	VM_BUG_ON_PAGE(!PageLRU(page), page);
+
 	__ClearPageLRU(page);
 
 	/* this shouldn't happen, so leave the flags to bad_page() */
@@ -87,6 +89,8 @@ static __always_inline enum lru_list page_lru(struct page *page)
 {
 	enum lru_list lru;
 
+	VM_BUG_ON_PAGE(PageActive(page) && PageUnevictable(page), page);
+
 	if (PageUnevictable(page))
 		lru = LRU_UNEVICTABLE;
 	else {
diff --git a/mm/swap.c b/mm/swap.c
index 38900d672051..31b844d4ed94 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -83,7 +83,6 @@ static void __page_cache_release(struct page *page)
 		unsigned long flags;
 
 		lruvec = lock_page_lruvec_irqsave(page, &flags);
-		VM_BUG_ON_PAGE(!PageLRU(page), page);
 		del_page_from_lru_list(page, lruvec);
 		__clear_page_lru_flags(page);
 		unlock_page_lruvec_irqrestore(lruvec, flags);
@@ -909,7 +908,6 @@ void release_pages(struct page **pages, int nr)
 			if (prev_lruvec != lruvec)
 				lock_batch = 0;
 
-			VM_BUG_ON_PAGE(!PageLRU(page), page);
 			del_page_from_lru_list(page, lruvec);
 			__clear_page_lru_flags(page);
 		}
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 452dd3818aa3..348a90096550 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4281,7 +4281,6 @@ void check_move_unevictable_pages(struct pagevec *pvec)
 
 		lruvec = relock_page_lruvec_irq(page, lruvec);
 		if (page_evictable(page) && PageUnevictable(page)) {
-			VM_BUG_ON_PAGE(PageActive(page), page);
 			del_page_from_lru_list(page, lruvec);
 			ClearPageUnevictable(page);
 			add_page_to_lru_list(page, lruvec);
-- 
2.30.0.280.ga3ce27912f-goog