linux-kernel - [PATCH] mm/page_isolation: don't putback unisolated page

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Date:   Sat, 4 Sep 2021 17:18:39 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <akpm@...ux-foundation.org>
CC:     <vbabka@...e.cz>, <iamjoonsoo.kim@....com>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, <linmiaohe@...wei.com>
Subject: [PATCH] mm/page_isolation: don't putback unisolated page

If __isolate_free_page() failed, due to zone watermark check, the page is
still on the free list. But this page will be put back to free list again
via __putback_isolated_page() now. This may trigger page->flags checks in
__free_one_page() if PageReported is set. Or we will corrupt the free list
because list_add() will be called for pages already on another list.

Fixes: 3c605096d315 ("mm/page_alloc: restrict max order of merging on isolated pageblock")
Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
---
 mm/page_isolation.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index 9bb562d5d194..7d70d772525c 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -93,10 +93,8 @@ static void unset_migratetype_isolate(struct page *page, unsigned migratetype)
 			buddy_pfn = __find_buddy_pfn(pfn, order);
 			buddy = page + (buddy_pfn - pfn);
 
-			if (!is_migrate_isolate_page(buddy)) {
-				__isolate_free_page(page, order);
-				isolated_page = true;
-			}
+			if (!is_migrate_isolate_page(buddy))
+				isolated_page = !!__isolate_free_page(page, order);
 		}
 	}
 
-- 
2.23.0