linux-kernel - [PATCH v2 1/9] mm: vmscan: add validation before spliting shmem large folio

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Message-Id: <413866f2f2d996cfbb5c906467b36c96b1a82e2d.1718690645.git.baolin.wang@linux.alibaba.com>
Date: Tue, 18 Jun 2024 14:54:13 +0800
From: Baolin Wang <baolin.wang@...ux.alibaba.com>
To: akpm@...ux-foundation.org,
	hughd@...gle.com
Cc: willy@...radead.org,
	david@...hat.com,
	wangkefeng.wang@...wei.com,
	chrisl@...nel.org,
	ying.huang@...el.com,
	21cnbao@...il.com,
	ryan.roberts@....com,
	shy828301@...il.com,
	ziy@...dia.com,
	ioworker0@...il.com,
	da.gomez@...sung.com,
	p.raghav@...sung.com,
	baolin.wang@...ux.alibaba.com,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/9] mm: vmscan: add validation before spliting shmem large folio

Add swap available space validation before spliting shmem large folio to
avoid redundant split, since we can not write shmem folio to the swap device
in this case.

Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
---
 mm/vmscan.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 1807e5d95dda..61465f92283f 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1237,6 +1237,14 @@ static unsigned int shrink_folio_list(struct list_head *folio_list,
 			}
 		} else if (folio_test_swapbacked(folio) &&
 			   folio_test_large(folio)) {
+
+			/*
+			 * Do not split shmem folio if no swap memory
+			 * available.
+			 */
+			if (!total_swap_pages)
+				goto activate_locked;
+
 			/* Split shmem folio */
 			if (split_folio_to_list(folio, folio_list))
 				goto keep_locked;
-- 
2.39.3