linux-kernel - [PATCH 1/2] mm: fix logic error of page_expected

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Date:   Wed, 14 Sep 2022 11:37:00 +0800
From:   "zhaoyang.huang" <zhaoyang.huang@...soc.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Matthew Wilcox <willy@...radead.org>,
        Zhaoyang Huang <huangzhaoyang@...il.com>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, <ke.wang@...soc.com>
Subject: [PATCH 1/2] mm: fix logic error of page_expected_state

From: Zhaoyang Huang <zhaoyang.huang@...soc.com>

The page with special page type will be deemed as bad page wrongly since
type share the same address with mapcount.

Signed-off-by: Zhaoyang Huang <zhaoyang.huang@...soc.com>
---
 include/linux/page-flags.h | 4 ++--
 mm/page_alloc.c            | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index e66f7aa..5d3274b 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -946,9 +946,9 @@ static inline bool is_page_hwpoison(struct page *page)
 #define PageType(page, flag)						\
 	((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
 
-static inline int page_has_type(struct page *page)
+static inline bool page_has_type(struct page *page)
 {
-	return (int)page->page_type < PAGE_MAPCOUNT_RESERVE;
+	return page->page_type < PAGE_MAPCOUNT_RESERVE;
 }
 
 #define PAGE_TYPE_OPS(uname, lname)					\
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e008a3d..3714680 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1164,7 +1164,7 @@ int split_free_page(struct page *free_page,
 static inline bool page_expected_state(struct page *page,
 					unsigned long check_flags)
 {
-	if (unlikely(atomic_read(&page->_mapcount) != -1))
+	if (unlikely(!page_has_type(page) && atomic_read(&page->_mapcount) != -1))
 		return false;
 
 	if (unlikely((unsigned long)page->mapping |
-- 
1.9.1