linux-kernel - [PATCH] mm: Do not start/end writeback for pages stored in zswap

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Message-ID: <20240610143037.812955-1-usamaarif642@gmail.com>
Date: Mon, 10 Jun 2024 15:30:37 +0100
From: Usama Arif <usamaarif642@...il.com>
To: akpm@...ux-foundation.org
Cc: willy@...radead.org,
	hannes@...xchg.org,
	yosryahmed@...gle.com,
	nphamcs@...il.com,
	chengming.zhou@...ux.dev,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	kernel-team@...a.com,
	Usama Arif <usamaarif642@...il.com>
Subject: [PATCH] mm: Do not start/end writeback for pages stored in zswap

start/end writeback combination incorrectly increments NR_WRITTEN
counter, eventhough the pages aren't written to disk. Pages successfully
stored in zswap should just unlock folio and return from writepage.

Signed-off-by: Usama Arif <usamaarif642@...il.com>
---
 mm/page_io.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/mm/page_io.c b/mm/page_io.c
index a360857cf75d..501784d79977 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -196,9 +196,7 @@ int swap_writepage(struct page *page, struct writeback_control *wbc)
 		return ret;
 	}
 	if (zswap_store(folio)) {
-		folio_start_writeback(folio);
 		folio_unlock(folio);
-		folio_end_writeback(folio);
 		return 0;
 	}
 	if (!mem_cgroup_zswap_writeback_enabled(folio_memcg(folio))) {
-- 
2.43.0