linux-kernel - [PATCH] mm/page_isolation: fix potential missing call to unset_migratetype

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Message-ID: <20210904092053.33037-1-linmiaohe@huawei.com>
Date:   Sat, 4 Sep 2021 17:20:53 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <akpm@...ux-foundation.org>
CC:     <mhocko@...e.com>, <vbabka@...e.cz>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, <linmiaohe@...wei.com>
Subject: [PATCH] mm/page_isolation: fix potential missing call to unset_migratetype_isolate()

In start_isolate_page_range() undo path, pfn_to_online_page() just checks
the first pfn in a pageblock while __first_valid_page() will traverse the
pageblock until the first online pfn is found. So we may miss the call to
unset_migratetype_isolate() in undo path and pages will remain isolated
unexpectedly. Fix this by calling undo_isolate_page_range() and this will
also help to remove some duplicated codes.

Fixes: 2ce13640b3f4 ("mm: __first_valid_page skip over offline pages")
Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
---
 mm/page_isolation.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index 471e3a13b541..9bb562d5d194 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -202,14 +202,7 @@ int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 	}
 	return 0;
 undo:
-	for (pfn = start_pfn;
-	     pfn < undo_pfn;
-	     pfn += pageblock_nr_pages) {
-		struct page *page = pfn_to_online_page(pfn);
-		if (!page)
-			continue;
-		unset_migratetype_isolate(page, migratetype);
-	}
+	undo_isolate_page_range(start_pfn, undo_pfn, migratetype);
 
 	return -EBUSY;
 }
-- 
2.23.0