Commit 5dc533f7 authored by Kairui Song's avatar Kairui Song Committed by Andrew Morton
Browse files

mm, swap: simplify swap table sanity range check 

The newly introduced helper, which checks bad slots and emptiness of a
cluster, can cover the older sanity check just fine, with a more rigorous
condition check.  So merge them.

Link: https://lkml.kernel.org/r/20260218-swap-table-p3-v3-8-f4e34be021a7@tencent.com


Signed-off-by: default avatarKairui Song <kasong@tencent.com>
Acked-by: default avatarChris Li <chrisl@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kairui Song <ryncsn@gmail.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 1307442b

mm/swapfile.c

+9 −26
Original line number Diff line number Diff line
@@ -459,9 +459,11 @@ static void swap_table_free(struct swap_table *table) 
 * One special case is that bad slots can't be freed, so check the number of

 * bad slots for swapoff, and non-swapoff path must never free bad slots.

 */

static void swap_cluster_assert_empty(struct swap_cluster_info *ci, bool swapoff)

static void swap_cluster_assert_empty(struct swap_cluster_info *ci,

				      unsigned int ci_off, unsigned int nr,

				      bool swapoff)

{

	unsigned int ci_off = 0, ci_end = SWAPFILE_CLUSTER;

	unsigned int ci_end = ci_off + nr;

	unsigned long swp_tb;

	int bad_slots = 0;
@@ -588,7 +590,7 @@ static void swap_cluster_schedule_discard(struct swap_info_struct *si, 


static void __free_cluster(struct swap_info_struct *si, struct swap_cluster_info *ci)

{

	swap_cluster_assert_empty(ci, false);

	swap_cluster_assert_empty(ci, 0, SWAPFILE_CLUSTER, false);

	swap_cluster_free_table(ci);

	move_cluster(si, ci, &si->free_clusters, CLUSTER_FLAG_FREE);

	ci->order = 0;
@@ -898,26 +900,6 @@ static bool cluster_scan_range(struct swap_info_struct *si, 
	return true;

}



/*

 * Currently, the swap table is not used for count tracking, just

 * do a sanity check here to ensure nothing leaked, so the swap

 * table should be empty upon freeing.

 */

static void swap_cluster_assert_table_empty(struct swap_cluster_info *ci,

				unsigned int start, unsigned int nr)

{

	unsigned int ci_off = start % SWAPFILE_CLUSTER;

	unsigned int ci_end = ci_off + nr;

	unsigned long swp_tb;



	if (IS_ENABLED(CONFIG_DEBUG_VM)) {

		do {

			swp_tb = __swap_table_get(ci, ci_off);

			VM_WARN_ON_ONCE(!swp_tb_is_null(swp_tb));

		} while (++ci_off < ci_end);

	}

}



static bool cluster_alloc_range(struct swap_info_struct *si,

				struct swap_cluster_info *ci,

				struct folio *folio,
@@ -943,13 +925,14 @@ static bool cluster_alloc_range(struct swap_info_struct *si, 
	if (likely(folio)) {

		order = folio_order(folio);

		nr_pages = 1 << order;

		swap_cluster_assert_empty(ci, offset % SWAPFILE_CLUSTER, nr_pages, false);

		__swap_cache_add_folio(ci, folio, swp_entry(si->type, offset));

	} else if (IS_ENABLED(CONFIG_HIBERNATION)) {

		order = 0;

		nr_pages = 1;

		WARN_ON_ONCE(si->swap_map[offset]);

		si->swap_map[offset] = 1;

		swap_cluster_assert_table_empty(ci, offset, 1);

		swap_cluster_assert_empty(ci, offset % SWAPFILE_CLUSTER, 1, false);

	} else {

		/* Allocation without folio is only possible with hibernation */

		WARN_ON_ONCE(1);
@@ -1768,7 +1751,7 @@ void swap_entries_free(struct swap_info_struct *si, 


	mem_cgroup_uncharge_swap(entry, nr_pages);

	swap_range_free(si, offset, nr_pages);

	swap_cluster_assert_table_empty(ci, offset, nr_pages);

	swap_cluster_assert_empty(ci, offset % SWAPFILE_CLUSTER, nr_pages, false);



	if (!ci->count)

		free_cluster(si, ci);
@@ -2780,7 +2763,7 @@ static void free_swap_cluster_info(struct swap_cluster_info *cluster_info, 
		/* Cluster with bad marks count will have a remaining table */

		spin_lock(&ci->lock);

		if (rcu_dereference_protected(ci->table, true)) {

			swap_cluster_assert_empty(ci, true);

			swap_cluster_assert_empty(ci, 0, SWAPFILE_CLUSTER, true);

			swap_cluster_free_table(ci);

		}

		spin_unlock(&ci->lock);