[PATCH 4/6] mm, swap: remove setting SWAP_MAP_BAD for discard cluster

From: Kemeng Shi
Date: Sat Feb 22 2025 - 02:15:25 EST


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@xxxxxxxxxxxxxxx>
---
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