linux-kernel - [PATCH 4/6] mm, swap: remove setting SWAP_MAP

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Message-Id: <20250222160850.505274-5-shikemeng@huaweicloud.com>
Date: Sun, 23 Feb 2025 00:08:48 +0800
From: Kemeng Shi <shikemeng@...weicloud.com>
To: akpm@...ux-foundation.org,
	kasong@...cent.com
Cc: linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 4/6] mm, swap: remove setting SWAP_MAP_BAD for discard cluster

Before alloc from a cluster, we will aqcuire cluster's lock and make
sure it is usable by cluster_is_usable(), so there is no need to
set SWAP_MAP_BAD for cluster to be discarded.

Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>
---
 mm/swapfile.c | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index fc45b9d56639..c640f77a464a 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -479,15 +479,6 @@ static void move_cluster(struct swap_info_struct *si,
 static void swap_cluster_schedule_discard(struct swap_info_struct *si,
 		struct swap_cluster_info *ci)
 {
-	unsigned int idx = cluster_index(si, ci);
-	/*
-	 * If scan_swap_map_slots() can't find a free cluster, it will check
-	 * si->swap_map directly. To make sure the discarding cluster isn't
-	 * taken by scan_swap_map_slots(), mark the swap entries bad (occupied).
-	 * It will be cleared after discard
-	 */
-	memset(si->swap_map + idx * SWAPFILE_CLUSTER,
-			SWAP_MAP_BAD, SWAPFILE_CLUSTER);
 	VM_BUG_ON(ci->flags == CLUSTER_FLAG_FREE);
 	move_cluster(si, ci, &si->discard_clusters, CLUSTER_FLAG_DISCARD);
 	schedule_work(&si->discard_work);
@@ -571,8 +562,6 @@ static bool swap_do_scheduled_discard(struct swap_info_struct *si)
 		 * return the cluster to allocation list.
 		 */
 		ci->flags = CLUSTER_FLAG_NONE;
-		memset(si->swap_map + idx * SWAPFILE_CLUSTER,
-				0, SWAPFILE_CLUSTER);
 		__free_cluster(si, ci);
 		spin_unlock(&ci->lock);
 		ret = true;
-- 
2.30.0