Merge tag 'mm-stable-2025-10-01-19-00' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

 - "mm, swap: improve cluster scan strategy" from Kairui Song improves
   performance and reduces the failure rate of swap cluster allocation

 - "support large align and nid in Rust allocators" from Vitaly Wool
   permits Rust allocators to set NUMA node and large alignment when
   perforning slub and vmalloc reallocs

 - "mm/damon/vaddr: support stat-purpose DAMOS" from Yueyang Pan extend
   DAMOS_STAT's handling of the DAMON operations sets for virtual
   address spaces for ops-level DAMOS filters

 - "execute PROCMAP_QUERY ioctl under per-vma lock" from Suren
   Baghdasaryan reduces mmap_lock contention during reads of
   /proc/pid/maps

 - "mm/mincore: minor clean up for swap cache checking" from Kairui Song
   performs some cleanup in the swap code

 - "mm: vm_normal_page*() improvements" from David Hildenbrand provides
   code cleanup in the pagemap code

 - "add persistent huge zero folio support" from Pankaj Raghav provides
   a block layer speedup by optionalls making the
   huge_zero_pagepersistent, instead of releasing it when its refcount
   falls to zero

 - "kho: fixes and cleanups" from Mike Rapoport adds a few touchups to
   the recently added Kexec Handover feature

 - "mm: make mm->flags a bitmap and 64-bit on all arches" from Lorenzo
   Stoakes turns mm_struct.flags into a bitmap. To end the constant
   struggle with space shortage on 32-bit conflicting with 64-bit's
   needs

 - "mm/swapfile.c and swap.h cleanup" from Chris Li cleans up some swap
   code

 - "selftests/mm: Fix false positives and skip unsupported tests" from
   Donet Tom fixes a few things in our selftests code

 - "prctl: extend PR_SET_THP_DISABLE to only provide THPs when advised"
   from David Hildenbrand "allows individual processes to opt-out of
   THP=always into THP=madvise, without affecting other workloads on the
   system".

   It's a long story - the [1/N] changelog spells out the considerations

 - "Add and use memdesc_flags_t" from Matthew Wilcox gets us started on
   the memdesc project. Please see

      https://kernelnewbies.org/MatthewWilcox/Memdescs and
      https://blogs.oracle.com/linux/post/introducing-memdesc

 - "Tiny optimization for large read operations" from Chi Zhiling
   improves the efficiency of the pagecache read path

 - "Better split_huge_page_test result check" from Zi Yan improves our
   folio splitting selftest code

 - "test that rmap behaves as expected" from Wei Yang adds some rmap
   selftests

 - "remove write_cache_pages()" from Christoph Hellwig removes that
   function and converts its two remaining callers

 - "selftests/mm: uffd-stress fixes" from Dev Jain fixes some UFFD
   selftests issues

 - "introduce kernel file mapped folios" from Boris Burkov introduces
   the concept of "kernel file pages". Using these permits btrfs to
   account its metadata pages to the root cgroup, rather than to the
   cgroups of random inappropriate tasks

 - "mm/pageblock: improve readability of some pageblock handling" from
   Wei Yang provides some readability improvements to the page allocator
   code

 - "mm/damon: support ARM32 with LPAE" from SeongJae Park teaches DAMON
   to understand arm32 highmem

 - "tools: testing: Use existing atomic.h for vma/maple tests" from
   Brendan Jackman performs some code cleanups and deduplication under
   tools/testing/

 - "maple_tree: Fix testing for 32bit compiles" from Liam Howlett fixes
   a couple of 32-bit issues in tools/testing/radix-tree.c

 - "kasan: unify kasan_enabled() and remove arch-specific
   implementations" from Sabyrzhan Tasbolatov moves KASAN arch-specific
   initialization code into a common arch-neutral implementation

 - "mm: remove zpool" from Johannes Weiner removes zspool - an
   indirection layer which now only redirects to a single thing
   (zsmalloc)

 - "mm: task_stack: Stack handling cleanups" from Pasha Tatashin makes a
   couple of cleanups in the fork code

 - "mm: remove nth_page()" from David Hildenbrand makes rather a lot of
   adjustments at various nth_page() callsites, eventually permitting
   the removal of that undesirable helper function

 - "introduce kasan.write_only option in hw-tags" from Yeoreum Yun
   creates a KASAN read-only mode for ARM, using that architecture's
   memory tagging feature. It is felt that a read-only mode KASAN is
   suitable for use in production systems rather than debug-only

 - "mm: hugetlb: cleanup hugetlb folio allocation" from Kefeng Wang does
   some tidying in the hugetlb folio allocation code

 - "mm: establish const-correctness for pointer parameters" from Max
   Kellermann makes quite a number of the MM API functions more accurate
   about the constness of their arguments. This was getting in the way
   of subsystems (in this case CEPH) when they attempt to improving
   their own const/non-const accuracy

 - "Cleanup free_pages() misuse" from Vishal Moola fixes a number of
   code sites which were confused over when to use free_pages() vs
   __free_pages()

 - "Add Rust abstraction for Maple Trees" from Alice Ryhl makes the
   mapletree code accessible to Rust. Required by nouveau and by its
   forthcoming successor: the new Rust Nova driver

 - "selftests/mm: split_huge_page_test: split_pte_mapped_thp
   improvements" from David Hildenbrand adds a fix and some cleanups to
   the thp selftesting code

 - "mm, swap: introduce swap table as swap cache (phase I)" from Chris
   Li and Kairui Song is the first step along the path to implementing
   "swap tables" - a new approach to swap allocation and state tracking
   which is expected to yield speed and space improvements. This
   patchset itself yields a 5-20% performance benefit in some situations

 - "Some ptdesc cleanups" from Matthew Wilcox utilizes the new memdesc
   layer to clean up the ptdesc code a little

 - "Fix va_high_addr_switch.sh test failure" from Chunyu Hu fixes some
   issues in our 5-level pagetable selftesting code

 - "Minor fixes for memory allocation profiling" from Suren Baghdasaryan
   addresses a couple of minor issues in relatively new memory
   allocation profiling feature

 - "Small cleanups" from Matthew Wilcox has a few cleanups in
   preparation for more memdesc work

 - "mm/damon: add addr_unit for DAMON_LRU_SORT and DAMON_RECLAIM" from
   Quanmin Yan makes some changes to DAMON in furtherance of supporting
   arm highmem

 - "selftests/mm: Add -Wunreachable-code and fix warnings" from Muhammad
   Anjum adds that compiler check to selftests code and fixes the
   fallout, by removing dead code

 - "Improvements to Victim Process Thawing and OOM Reaper Traversal
   Order" from zhongjinji makes a number of improvements in the OOM
   killer: mainly thawing a more appropriate group of victim threads so
   they can release resources

 - "mm/damon: misc fixups and improvements for 6.18" from SeongJae Park
   is a bunch of small and unrelated fixups for DAMON

 - "mm/damon: define and use DAMON initialization check function" from
   SeongJae Park implement reliability and maintainability improvements
   to a recently-added bug fix

 - "mm/damon/stat: expose auto-tuned intervals and non-idle ages" from
   SeongJae Park provides additional transparency to userspace clients
   of the DAMON_STAT information

 - "Expand scope of khugepaged anonymous collapse" from Dev Jain removes
   some constraints on khubepaged's collapsing of anon VMAs. It also
   increases the success rate of MADV_COLLAPSE against an anon vma

 - "mm: do not assume file == vma->vm_file in compat_vma_mmap_prepare()"
   from Lorenzo Stoakes moves us further towards removal of
   file_operations.mmap(). This patchset concentrates upon clearing up
   the treatment of stacked filesystems

 - "mm: Improve mlock tracking for large folios" from Kiryl Shutsemau
   provides some fixes and improvements to mlock's tracking of large
   folios. /proc/meminfo's "Mlocked" field became more accurate

 - "mm/ksm: Fix incorrect accounting of KSM counters during fork" from
   Donet Tom fixes several user-visible KSM stats inaccuracies across
   forks and adds selftest code to verify these counters

 - "mm_slot: fix the usage of mm_slot_entry" from Wei Yang addresses
   some potential but presently benign issues in KSM's mm_slot handling

* tag 'mm-stable-2025-10-01-19-00' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (372 commits)
  mm: swap: check for stable address space before operating on the VMA
  mm: convert folio_page() back to a macro
  mm/khugepaged: use start_addr/addr for improved readability
  hugetlbfs: skip VMAs without shareable locks in hugetlb_vmdelete_list
  alloc_tag: fix boot failure due to NULL pointer dereference
  mm: silence data-race in update_hiwater_rss
  mm/memory-failure: don't select MEMORY_ISOLATION
  mm/khugepaged: remove definition of struct khugepaged_mm_slot
  mm/ksm: get mm_slot by mm_slot_entry() when slot is !NULL
  hugetlb: increase number of reserving hugepages via cmdline
  selftests/mm: add fork inheritance test for ksm_merging_pages counter
  mm/ksm: fix incorrect KSM counter handling in mm_struct during fork
  drivers/base/node: fix double free in register_one_node()
  mm: remove PMD alignment constraint in execmem_vmalloc()
  mm/memory_hotplug: fix typo 'esecially' -> 'especially'
  mm/rmap: improve mlock tracking for large folios
  mm/filemap: map entire large folio faultaround
  mm/fault: try to map the entire file folio in finish_fault()
  mm/rmap: mlock large folios in try_to_unmap_one()
  mm/rmap: fix a mlock race condition in folio_referenced_one()
  ...

1 files changed, 246 insertions, 242 deletions

diff --git a/mm/swap_state.c b/mm/swap_state.c
index c354435a0923..b13e9c4baa90 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -23,6 +23,7 @@
 #include <linux/huge_mm.h>
 #include <linux/shmem_fs.h>
 #include "internal.h"
+#include "swap_table.h"
 #include "swap.h"
 
 /*
@@ -36,8 +37,11 @@ static const struct address_space_operations swap_aops = {
 #endif
 };
 
-struct address_space *swapper_spaces[MAX_SWAPFILES] __read_mostly;
-static unsigned int nr_swapper_spaces[MAX_SWAPFILES] __read_mostly;
+/* Set swap_space as read only as swap cache is handled by swap table */
+struct address_space swap_space __ro_after_init = {
+	.a_ops = &swap_aops,
+};
+
 static bool enable_vma_readahead __read_mostly = true;
 
 #define SWAP_RA_ORDER_CEILING	5
@@ -69,150 +73,237 @@ void show_swap_cache_info(void)
 	printk("Total swap = %lukB\n", K(total_swap_pages));
 }
 
-void *get_shadow_from_swap_cache(swp_entry_t entry)
+/**
+ * swap_cache_get_folio - Looks up a folio in the swap cache.
+ * @entry: swap entry used for the lookup.
+ *
+ * A found folio will be returned unlocked and with its refcount increased.
+ *
+ * Context: Caller must ensure @entry is valid and protect the swap device
+ * with reference count or locks.
+ * Return: Returns the found folio on success, NULL otherwise. The caller
+ * must lock nd check if the folio still matches the swap entry before
+ * use (e.g., folio_matches_swap_entry).
+ */
+struct folio *swap_cache_get_folio(swp_entry_t entry)
 {
-	struct address_space *address_space = swap_address_space(entry);
-	pgoff_t idx = swap_cache_index(entry);
-	void *shadow;
+	unsigned long swp_tb;
+	struct folio *folio;
+
+	for (;;) {
+		swp_tb = swap_table_get(__swap_entry_to_cluster(entry),
+					swp_cluster_offset(entry));
+		if (!swp_tb_is_folio(swp_tb))
+			return NULL;
+		folio = swp_tb_to_folio(swp_tb);
+		if (likely(folio_try_get(folio)))
+			return folio;
+	}
 
-	shadow = xa_load(&address_space->i_pages, idx);
-	if (xa_is_value(shadow))
-		return shadow;
 	return NULL;
 }
 
-/*
- * add_to_swap_cache resembles filemap_add_folio on swapper_space,
- * but sets SwapCache flag and 'swap' instead of mapping and index.
+/**
+ * swap_cache_get_shadow - Looks up a shadow in the swap cache.
+ * @entry: swap entry used for the lookup.
+ *
+ * Context: Caller must ensure @entry is valid and protect the swap device
+ * with reference count or locks.
+ * Return: Returns either NULL or an XA_VALUE (shadow).
  */
-int add_to_swap_cache(struct folio *folio, swp_entry_t entry,
-			gfp_t gfp, void **shadowp)
+void *swap_cache_get_shadow(swp_entry_t entry)
 {
-	struct address_space *address_space = swap_address_space(entry);
-	pgoff_t idx = swap_cache_index(entry);
-	XA_STATE_ORDER(xas, &address_space->i_pages, idx, folio_order(folio));
-	unsigned long i, nr = folio_nr_pages(folio);
-	void *old;
+	unsigned long swp_tb;
 
-	xas_set_update(&xas, workingset_update_node);
+	swp_tb = swap_table_get(__swap_entry_to_cluster(entry),
+				swp_cluster_offset(entry));
+	if (swp_tb_is_shadow(swp_tb))
+		return swp_tb_to_shadow(swp_tb);
+	return NULL;
+}
 
-	VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
-	VM_BUG_ON_FOLIO(folio_test_swapcache(folio), folio);
-	VM_BUG_ON_FOLIO(!folio_test_swapbacked(folio), folio);
+/**
+ * swap_cache_add_folio - Add a folio into the swap cache.
+ * @folio: The folio to be added.
+ * @entry: The swap entry corresponding to the folio.
+ * @gfp: gfp_mask for XArray node allocation.
+ * @shadowp: If a shadow is found, return the shadow.
+ *
+ * Context: Caller must ensure @entry is valid and protect the swap device
+ * with reference count or locks.
+ * The caller also needs to update the corresponding swap_map slots with
+ * SWAP_HAS_CACHE bit to avoid race or conflict.
+ */
+void swap_cache_add_folio(struct folio *folio, swp_entry_t entry, void **shadowp)
+{
+	void *shadow = NULL;
+	unsigned long old_tb, new_tb;
+	struct swap_cluster_info *ci;
+	unsigned int ci_start, ci_off, ci_end;
+	unsigned long nr_pages = folio_nr_pages(folio);
+
+	VM_WARN_ON_ONCE_FOLIO(!folio_test_locked(folio), folio);
+	VM_WARN_ON_ONCE_FOLIO(folio_test_swapcache(folio), folio);
+	VM_WARN_ON_ONCE_FOLIO(!folio_test_swapbacked(folio), folio);
+
+	new_tb = folio_to_swp_tb(folio);
+	ci_start = swp_cluster_offset(entry);
+	ci_end = ci_start + nr_pages;
+	ci_off = ci_start;
+	ci = swap_cluster_lock(__swap_entry_to_info(entry), swp_offset(entry));
+	do {
+		old_tb = __swap_table_xchg(ci, ci_off, new_tb);
+		WARN_ON_ONCE(swp_tb_is_folio(old_tb));
+		if (swp_tb_is_shadow(old_tb))
+			shadow = swp_tb_to_shadow(old_tb);
+	} while (++ci_off < ci_end);
 
-	folio_ref_add(folio, nr);
+	folio_ref_add(folio, nr_pages);
 	folio_set_swapcache(folio);
 	folio->swap = entry;
+	swap_cluster_unlock(ci);
 
-	do {
-		xas_lock_irq(&xas);
-		xas_create_range(&xas);
-		if (xas_error(&xas))
-			goto unlock;
-		for (i = 0; i < nr; i++) {
-			VM_BUG_ON_FOLIO(xas.xa_index != idx + i, folio);
-			if (shadowp) {
-				old = xas_load(&xas);
-				if (xa_is_value(old))
-					*shadowp = old;
-			}
-			xas_store(&xas, folio);
-			xas_next(&xas);
-		}
-		address_space->nrpages += nr;
-		__node_stat_mod_folio(folio, NR_FILE_PAGES, nr);
-		__lruvec_stat_mod_folio(folio, NR_SWAPCACHE, nr);
-unlock:
-		xas_unlock_irq(&xas);
-	} while (xas_nomem(&xas, gfp));
-
-	if (!xas_error(&xas))
-		return 0;
+	node_stat_mod_folio(folio, NR_FILE_PAGES, nr_pages);
+	lruvec_stat_mod_folio(folio, NR_SWAPCACHE, nr_pages);
 
-	folio_clear_swapcache(folio);
-	folio_ref_sub(folio, nr);
-	return xas_error(&xas);
+	if (shadowp)
+		*shadowp = shadow;
 }
 
-/*
- * This must be called only on folios that have
- * been verified to be in the swap cache.
+/**
+ * __swap_cache_del_folio - Removes a folio from the swap cache.
+ * @ci: The locked swap cluster.
+ * @folio: The folio.
+ * @entry: The first swap entry that the folio corresponds to.
+ * @shadow: shadow value to be filled in the swap cache.
+ *
+ * Removes a folio from the swap cache and fills a shadow in place.
+ * This won't put the folio's refcount. The caller has to do that.
+ *
+ * Context: Caller must ensure the folio is locked and in the swap cache
+ * using the index of @entry, and lock the cluster that holds the entries.
  */
-void __delete_from_swap_cache(struct folio *folio,
-			swp_entry_t entry, void *shadow)
+void __swap_cache_del_folio(struct swap_cluster_info *ci, struct folio *folio,
+			    swp_entry_t entry, void *shadow)
 {
-	struct address_space *address_space = swap_address_space(entry);
-	int i;
-	long nr = folio_nr_pages(folio);
-	pgoff_t idx = swap_cache_index(entry);
-	XA_STATE(xas, &address_space->i_pages, idx);
-
-	xas_set_update(&xas, workingset_update_node);
-
-	VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
-	VM_BUG_ON_FOLIO(!folio_test_swapcache(folio), folio);
-	VM_BUG_ON_FOLIO(folio_test_writeback(folio), folio);
-
-	for (i = 0; i < nr; i++) {
-		void *entry = xas_store(&xas, shadow);
-		VM_BUG_ON_PAGE(entry != folio, entry);
-		xas_next(&xas);
-	}
+	unsigned long old_tb, new_tb;
+	unsigned int ci_start, ci_off, ci_end;
+	unsigned long nr_pages = folio_nr_pages(folio);
+
+	VM_WARN_ON_ONCE(__swap_entry_to_cluster(entry) != ci);
+	VM_WARN_ON_ONCE_FOLIO(!folio_test_locked(folio), folio);
+	VM_WARN_ON_ONCE_FOLIO(!folio_test_swapcache(folio), folio);
+	VM_WARN_ON_ONCE_FOLIO(folio_test_writeback(folio), folio);
+
+	new_tb = shadow_swp_to_tb(shadow);
+	ci_start = swp_cluster_offset(entry);
+	ci_end = ci_start + nr_pages;
+	ci_off = ci_start;
+	do {
+		/* If shadow is NULL, we sets an empty shadow */
+		old_tb = __swap_table_xchg(ci, ci_off, new_tb);
+		WARN_ON_ONCE(!swp_tb_is_folio(old_tb) ||
+			     swp_tb_to_folio(old_tb) != folio);
+	} while (++ci_off < ci_end);
+
 	folio->swap.val = 0;
 	folio_clear_swapcache(folio);
-	address_space->nrpages -= nr;
-	__node_stat_mod_folio(folio, NR_FILE_PAGES, -nr);
-	__lruvec_stat_mod_folio(folio, NR_SWAPCACHE, -nr);
+	node_stat_mod_folio(folio, NR_FILE_PAGES, -nr_pages);
+	lruvec_stat_mod_folio(folio, NR_SWAPCACHE, -nr_pages);
 }
 
-/*
- * This must be called only on folios that have
- * been verified to be in the swap cache and locked.
- * It will never put the folio into the free list,
- * the caller has a reference on the folio.
+/**
+ * swap_cache_del_folio - Removes a folio from the swap cache.
+ * @folio: The folio.
+ *
+ * Same as __swap_cache_del_folio, but handles lock and refcount. The
+ * caller must ensure the folio is either clean or has a swap count
+ * equal to zero, or it may cause data loss.
+ *
+ * Context: Caller must ensure the folio is locked and in the swap cache.
  */
-void delete_from_swap_cache(struct folio *folio)
+void swap_cache_del_folio(struct folio *folio)
 {
+	struct swap_cluster_info *ci;
 	swp_entry_t entry = folio->swap;
-	struct address_space *address_space = swap_address_space(entry);
 
-	xa_lock_irq(&address_space->i_pages);
-	__delete_from_swap_cache(folio, entry, NULL);
-	xa_unlock_irq(&address_space->i_pages);
+	ci = swap_cluster_lock(__swap_entry_to_info(entry), swp_offset(entry));
+	__swap_cache_del_folio(ci, folio, entry, NULL);
+	swap_cluster_unlock(ci);
 
 	put_swap_folio(folio, entry);
 	folio_ref_sub(folio, folio_nr_pages(folio));
 }
 
-void clear_shadow_from_swap_cache(int type, unsigned long begin,
-				unsigned long end)
+/**
+ * __swap_cache_replace_folio - Replace a folio in the swap cache.
+ * @ci: The locked swap cluster.
+ * @old: The old folio to be replaced.
+ * @new: The new folio.
+ *
+ * Replace an existing folio in the swap cache with a new folio. The
+ * caller is responsible for setting up the new folio's flag and swap
+ * entries. Replacement will take the new folio's swap entry value as
+ * the starting offset to override all slots covered by the new folio.
+ *
+ * Context: Caller must ensure both folios are locked, and lock the
+ * cluster that holds the old folio to be replaced.
+ */
+void __swap_cache_replace_folio(struct swap_cluster_info *ci,
+				struct folio *old, struct folio *new)
 {
-	unsigned long curr = begin;
-	void *old;
-
-	for (;;) {
-		swp_entry_t entry = swp_entry(type, curr);
-		unsigned long index = curr & SWAP_ADDRESS_SPACE_MASK;
-		struct address_space *address_space = swap_address_space(entry);
-		XA_STATE(xas, &address_space->i_pages, index);
-
-		xas_set_update(&xas, workingset_update_node);
-
-		xa_lock_irq(&address_space->i_pages);
-		xas_for_each(&xas, old, min(index + (end - curr), SWAP_ADDRESS_SPACE_PAGES)) {
-			if (!xa_is_value(old))
-				continue;
-			xas_store(&xas, NULL);
-		}
-		xa_unlock_irq(&address_space->i_pages);
+	swp_entry_t entry = new->swap;
+	unsigned long nr_pages = folio_nr_pages(new);
+	unsigned int ci_off = swp_cluster_offset(entry);
+	unsigned int ci_end = ci_off + nr_pages;
+	unsigned long old_tb, new_tb;
+
+	VM_WARN_ON_ONCE(!folio_test_swapcache(old) || !folio_test_swapcache(new));
+	VM_WARN_ON_ONCE(!folio_test_locked(old) || !folio_test_locked(new));
+	VM_WARN_ON_ONCE(!entry.val);
+
+	/* Swap cache still stores N entries instead of a high-order entry */
+	new_tb = folio_to_swp_tb(new);
+	do {
+		old_tb = __swap_table_xchg(ci, ci_off, new_tb);
+		WARN_ON_ONCE(!swp_tb_is_folio(old_tb) || swp_tb_to_folio(old_tb) != old);
+	} while (++ci_off < ci_end);
 
-		/* search the next swapcache until we meet end */
-		curr = ALIGN((curr + 1), SWAP_ADDRESS_SPACE_PAGES);
-		if (curr > end)
-			break;
+	/*
+	 * If the old folio is partially replaced (e.g., splitting a large
+	 * folio, the old folio is shrunk, and new split sub folios replace
+	 * the shrunk part), ensure the new folio doesn't overlap it.
+	 */
+	if (IS_ENABLED(CONFIG_DEBUG_VM) &&
+	    folio_order(old) != folio_order(new)) {
+		ci_off = swp_cluster_offset(old->swap);
+		ci_end = ci_off + folio_nr_pages(old);
+		while (ci_off++ < ci_end)
+			WARN_ON_ONCE(swp_tb_to_folio(__swap_table_get(ci, ci_off)) != old);
 	}
 }
 
+/**
+ * swap_cache_clear_shadow - Clears a set of shadows in the swap cache.
+ * @entry: The starting index entry.
+ * @nr_ents: How many slots need to be cleared.
+ *
+ * Context: Caller must ensure the range is valid, all in one single cluster,
+ * not occupied by any folio, and lock the cluster.
+ */
+void __swap_cache_clear_shadow(swp_entry_t entry, int nr_ents)
+{
+	struct swap_cluster_info *ci = __swap_entry_to_cluster(entry);
+	unsigned int ci_off = swp_cluster_offset(entry), ci_end;
+	unsigned long old;
+
+	ci_end = ci_off + nr_ents;
+	do {
+		old = __swap_table_xchg(ci, ci_off, null_to_swp_tb());
+		WARN_ON_ONCE(swp_tb_is_folio(old));
+	} while (++ci_off < ci_end);
+}
+
 /*
  * If we are the only user, then try to free up the swap cache.
  *
@@ -272,100 +363,50 @@ static inline bool swap_use_vma_readahead(void)
 	return READ_ONCE(enable_vma_readahead) && !atomic_read(&nr_rotate_swap);
 }
 
-/*
- * Lookup a swap entry in the swap cache. A found folio will be returned
- * unlocked and with its refcount incremented - we rely on the kernel
- * lock getting page table operations atomic even if we drop the folio
- * lock before returning.
- *
- * Caller must lock the swap device or hold a reference to keep it valid.
+/**
+ * swap_update_readahead - Update the readahead statistics of VMA or globally.
+ * @folio: the swap cache folio that just got hit.
+ * @vma: the VMA that should be updated, could be NULL for global update.
+ * @addr: the addr that triggered the swapin, ignored if @vma is NULL.
  */
-struct folio *swap_cache_get_folio(swp_entry_t entry,
-		struct vm_area_struct *vma, unsigned long addr)
+void swap_update_readahead(struct folio *folio, struct vm_area_struct *vma,
+			   unsigned long addr)
 {
-	struct folio *folio;
-
-	folio = filemap_get_folio(swap_address_space(entry), swap_cache_index(entry));
-	if (!IS_ERR(folio)) {
-		bool vma_ra = swap_use_vma_readahead();
-		bool readahead;
+	bool readahead, vma_ra = swap_use_vma_readahead();
 
-		/*
-		 * At the moment, we don't support PG_readahead for anon THP
-		 * so let's bail out rather than confusing the readahead stat.
-		 */
-		if (unlikely(folio_test_large(folio)))
-			return folio;
-
-		readahead = folio_test_clear_readahead(folio);
-		if (vma && vma_ra) {
-			unsigned long ra_val;
-			int win, hits;
-
-			ra_val = GET_SWAP_RA_VAL(vma);
-			win = SWAP_RA_WIN(ra_val);
-			hits = SWAP_RA_HITS(ra_val);
-			if (readahead)
-				hits = min_t(int, hits + 1, SWAP_RA_HITS_MAX);
-			atomic_long_set(&vma->swap_readahead_info,
-					SWAP_RA_VAL(addr, win, hits));
-		}
-
-		if (readahead) {
-			count_vm_event(SWAP_RA_HIT);
-			if (!vma || !vma_ra)
-				atomic_inc(&swapin_readahead_hits);
-		}
-	} else {
-		folio = NULL;
+	/*
+	 * At the moment, we don't support PG_readahead for anon THP
+	 * so let's bail out rather than confusing the readahead stat.
+	 */
+	if (unlikely(folio_test_large(folio)))
+		return;
+
+	readahead = folio_test_clear_readahead(folio);
+	if (vma && vma_ra) {
+		unsigned long ra_val;
+		int win, hits;
+
+		ra_val = GET_SWAP_RA_VAL(vma);
+		win = SWAP_RA_WIN(ra_val);
+		hits = SWAP_RA_HITS(ra_val);
+		if (readahead)
+			hits = min_t(int, hits + 1, SWAP_RA_HITS_MAX);
+		atomic_long_set(&vma->swap_readahead_info,
+				SWAP_RA_VAL(addr, win, hits));
 	}
 
-	return folio;
-}
-
-/**
- * filemap_get_incore_folio - Find and get a folio from the page or swap caches.
- * @mapping: The address_space to search.
- * @index: The page cache index.
- *
- * This differs from filemap_get_folio() in that it will also look for the
- * folio in the swap cache.
- *
- * Return: The found folio or %NULL.
- */
-struct folio *filemap_get_incore_folio(struct address_space *mapping,
-		pgoff_t index)
-{
-	swp_entry_t swp;
-	struct swap_info_struct *si;
-	struct folio *folio = filemap_get_entry(mapping, index);
-
-	if (!folio)
-		return ERR_PTR(-ENOENT);
-	if (!xa_is_value(folio))
-		return folio;
-	if (!shmem_mapping(mapping))
-		return ERR_PTR(-ENOENT);
-
-	swp = radix_to_swp_entry(folio);
-	/* There might be swapin error entries in shmem mapping. */
-	if (non_swap_entry(swp))
-		return ERR_PTR(-ENOENT);
-	/* Prevent swapoff from happening to us */
-	si = get_swap_device(swp);
-	if (!si)
-		return ERR_PTR(-ENOENT);
-	index = swap_cache_index(swp);
-	folio = filemap_get_folio(swap_address_space(swp), index);
-	put_swap_device(si);
-	return folio;
+	if (readahead) {
+		count_vm_event(SWAP_RA_HIT);
+		if (!vma || !vma_ra)
+			atomic_inc(&swapin_readahead_hits);
+	}
 }
 
 struct folio *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
 		struct mempolicy *mpol, pgoff_t ilx, bool *new_page_allocated,
 		bool skip_if_exists)
 {
-	struct swap_info_struct *si = swp_swap_info(entry);
+	struct swap_info_struct *si = __swap_entry_to_info(entry);
 	struct folio *folio;
 	struct folio *new_folio = NULL;
 	struct folio *result = NULL;
@@ -374,14 +415,13 @@ struct folio *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
 	*new_page_allocated = false;
 	for (;;) {
 		int err;
+
 		/*
-		 * First check the swap cache.  Since this is normally
-		 * called after swap_cache_get_folio() failed, re-calling
-		 * that would confuse statistics.
+		 * Check the swap cache first, if a cached folio is found,
+		 * return it unlocked. The caller will lock and check it.
 		 */
-		folio = filemap_get_folio(swap_address_space(entry),
-					  swap_cache_index(entry));
-		if (!IS_ERR(folio))
+		folio = swap_cache_get_folio(entry);
+		if (folio)
 			goto got_folio;
 
 		/*
@@ -423,7 +463,7 @@ struct folio *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
 			goto put_and_return;
 
 		/*
-		 * We might race against __delete_from_swap_cache(), and
+		 * We might race against __swap_cache_del_folio(), and
 		 * stumble across a swap_map entry whose SWAP_HAS_CACHE
 		 * has not yet been cleared.  Or race against another
 		 * __read_swap_cache_async(), which has set SWAP_HAS_CACHE
@@ -441,10 +481,7 @@ struct folio *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
 	if (mem_cgroup_swapin_charge_folio(new_folio, NULL, gfp_mask, entry))
 		goto fail_unlock;
 
-	/* May fail (-ENOMEM) if XArray node allocation failed. */
-	if (add_to_swap_cache(new_folio, entry, gfp_mask & GFP_RECLAIM_MASK, &shadow))
-		goto fail_unlock;
-
+	swap_cache_add_folio(new_folio, entry, &shadow);
 	memcg1_swapin(entry, 1);
 
 	if (shadow)
@@ -590,7 +627,7 @@ struct folio *swap_cluster_readahead(swp_entry_t entry, gfp_t gfp_mask,
 	unsigned long offset = entry_offset;
 	unsigned long start_offset, end_offset;
 	unsigned long mask;
-	struct swap_info_struct *si = swp_swap_info(entry);
+	struct swap_info_struct *si = __swap_entry_to_info(entry);
 	struct blk_plug plug;
 	struct swap_iocb *splug = NULL;
 	bool page_allocated;
@@ -636,41 +673,6 @@ skip:
 	return folio;
 }
 
-int init_swap_address_space(unsigned int type, unsigned long nr_pages)
-{
-	struct address_space *spaces, *space;
-	unsigned int i, nr;
-
-	nr = DIV_ROUND_UP(nr_pages, SWAP_ADDRESS_SPACE_PAGES);
-	spaces = kvcalloc(nr, sizeof(struct address_space), GFP_KERNEL);
-	if (!spaces)
-		return -ENOMEM;
-	for (i = 0; i < nr; i++) {
-		space = spaces + i;
-		xa_init_flags(&space->i_pages, XA_FLAGS_LOCK_IRQ);
-		atomic_set(&space->i_mmap_writable, 0);
-		space->a_ops = &swap_aops;
-		/* swap cache doesn't use writeback related tags */
-		mapping_set_no_writeback_tags(space);
-	}
-	nr_swapper_spaces[type] = nr;
-	swapper_spaces[type] = spaces;
-
-	return 0;
-}
-
-void exit_swap_address_space(unsigned int type)
-{
-	int i;
-	struct address_space *spaces = swapper_spaces[type];
-
-	for (i = 0; i < nr_swapper_spaces[type]; i++)
-		VM_WARN_ON_ONCE(!mapping_empty(&spaces[i]));
-	kvfree(spaces);
-	nr_swapper_spaces[type] = 0;
-	swapper_spaces[type] = NULL;
-}
-
 static int swap_vma_ra_win(struct vm_fault *vmf, unsigned long *start,
 			   unsigned long *end)
 {
@@ -843,7 +845,7 @@ static const struct attribute_group swap_attr_group = {
 	.attrs = swap_attrs,
 };
 
-static int __init swap_init_sysfs(void)
+static int __init swap_init(void)
 {
 	int err;
 	struct kobject *swap_kobj;
@@ -858,11 +860,13 @@ static int __init swap_init_sysfs(void)
 		pr_err("failed to register swap group\n");
 		goto delete_obj;
 	}
+	/* Swap cache writeback is LRU based, no tags for it */
+	mapping_set_no_writeback_tags(&swap_space);
 	return 0;
 
 delete_obj:
 	kobject_put(swap_kobj);
 	return err;
 }
-subsys_initcall(swap_init_sysfs);
+subsys_initcall(swap_init);
 #endif