linux-kernel - [PATCH 4/5] mm: shmem: keep inode in swaplist when failed to allocate swap entry in shmem

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Message-Id: <20250514165047.946884-5-shikemeng@huaweicloud.com>
Date: Thu, 15 May 2025 00:50:46 +0800
From: Kemeng Shi <shikemeng@...weicloud.com>
To: hughd@...gle.com,
	baolin.wang@...ux.alibaba.com,
	akpm@...ux-foundation.org
Cc: linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 4/5] mm: shmem: keep inode in swaplist when failed to allocate swap entry in shmem_writepage()

Even if we fail to allocate a swap entry, the inode might have previously
allocated entry and we might take inode containing swap entry off swaplist.
As a result, try_to_unuse() may enter a potential dead loop to repeatedly
look for inode and clean it's swap entry.
Address this by keeping inode in swaplist even if we fail to allocate
swap entry as it does not pose significant problem to keep inode without
swap entry in swaplist.

Fixes: b487a2da3575b ("mm, swap: simplify folio swap allocation")
Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>
---
 mm/shmem.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index 0fed94c2bc09..dfd2f730833c 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1651,8 +1651,6 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
 		BUG_ON(folio_mapped(folio));
 		return swap_writepage(&folio->page, wbc);
 	}
-
-	list_del_init(&info->swaplist);
 	mutex_unlock(&shmem_swaplist_mutex);
 	if (nr_pages > 1)
 		goto try_split;
-- 
2.30.0