diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 1ea896887ee4..b70124b9c7c1 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -142,6 +142,15 @@ enum pageflags {
 
 	PG_readahead = PG_reclaim,
 
+	/*
+	 * Depending on the way an anonymous folio can be mapped into a page
+	 * table (e.g., single PMD/PUD/CONT of the head page vs. PTE-mapped
+	 * THP), PG_anon_exclusive may be set only for the head page or for
+	 * tail pages of an anonymous folio. For now, we only expect it to be
+	 * set on tail pages for PTE-mapped THP.
+	 */
+	PG_anon_exclusive = PG_mappedtodisk,
+
 	/* Filesystems */
 	PG_checked = PG_owner_priv_1,
 
@@ -176,7 +185,7 @@ enum pageflags {
 	 * Indicates that at least one subpage is hwpoisoned in the
 	 * THP.
 	 */
-	PG_has_hwpoisoned = PG_mappedtodisk,
+	PG_has_hwpoisoned = PG_error,
 #endif
 
 	/* non-lru isolated movable page */
@@ -1002,6 +1011,34 @@ extern bool is_free_buddy_page(struct page *page);
 
 PAGEFLAG(Isolated, isolated, PF_ANY);
 
+static __always_inline int PageAnonExclusive(struct page *page)
+{
+	VM_BUG_ON_PGFLAGS(!PageAnon(page), page);
+	VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
+	return test_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
+}
+
+static __always_inline void SetPageAnonExclusive(struct page *page)
+{
+	VM_BUG_ON_PGFLAGS(!PageAnon(page) || PageKsm(page), page);
+	VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
+	set_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
+}
+
+static __always_inline void ClearPageAnonExclusive(struct page *page)
+{
+	VM_BUG_ON_PGFLAGS(!PageAnon(page) || PageKsm(page), page);
+	VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
+	clear_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
+}
+
+static __always_inline void __ClearPageAnonExclusive(struct page *page)
+{
+	VM_BUG_ON_PGFLAGS(!PageAnon(page), page);
+	VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
+	__clear_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
+}
+
 #ifdef CONFIG_MMU
 #define __PG_MLOCKED		(1UL << PG_mlocked)
 #else
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 7a6052a984e9..03cbb75bcb54 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1677,6 +1677,8 @@ void free_huge_page(struct page *page)
 	VM_BUG_ON_PAGE(page_mapcount(page), page);
 
 	hugetlb_set_page_subpool(page, NULL);
+	if (PageAnon(page))
+		__ClearPageAnonExclusive(page);
 	page->mapping = NULL;
 	restore_reserve = HPageRestoreReserve(page);
 	ClearHPageRestoreReserve(page);
diff --git a/mm/memory.c b/mm/memory.c
index d4dba178e130..0b0727758c86 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3667,6 +3667,17 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 		goto out_nomap;
 	}
 
+	/*
+	 * PG_anon_exclusive reuses PG_mappedtodisk for anon pages. A swap pte
+	 * must never point at an anonymous page in the swapcache that is
+	 * PG_anon_exclusive. Sanity check that this holds and especially, that
+	 * no filesystem set PG_mappedtodisk on a page in the swapcache. Sanity
+	 * check after taking the PT lock and making sure that nobody
+	 * concurrently faulted in this page and set PG_anon_exclusive.
+	 */
+	BUG_ON(!PageAnon(page) && PageMappedToDisk(page));
+	BUG_ON(PageAnon(page) && PageAnonExclusive(page));
+
 	/*
 	 * Remove the swap entry and conditionally try to free up the swapcache.
 	 * We're already holding a reference on the page but haven't mapped it
diff --git a/mm/memremap.c b/mm/memremap.c
index c33bcd0398c9..2b92e97cb25b 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -459,6 +459,15 @@ void free_zone_device_page(struct page *page)
 
 	mem_cgroup_uncharge(page_folio(page));
 
+	/*
+	 * Note: we don't expect anonymous compound pages yet. Once supported
+	 * and we could PTE-map them similar to THP, we'd have to clear
+	 * PG_anon_exclusive on all tail pages.
+	 */
+	VM_BUG_ON_PAGE(PageAnon(page) && PageCompound(page), page);
+	if (PageAnon(page))
+		__ClearPageAnonExclusive(page);
+
 	/*
 	 * When a device managed page is freed, the page->mapping field
 	 * may still contain a (stale) mapping value. For example, the
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 0ad7ed7ded21..a7847324d476 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1796,6 +1796,10 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
 		goto out;
 	}
 
+	/* See do_swap_page() */
+	BUG_ON(!PageAnon(page) && PageMappedToDisk(page));
+	BUG_ON(PageAnon(page) && PageAnonExclusive(page));
+
 	dec_mm_counter(vma->vm_mm, MM_SWAPENTS);
 	inc_mm_counter(vma->vm_mm, MM_ANONPAGES);
 	get_page(page);
diff --git a/tools/vm/page-types.c b/tools/vm/page-types.c
index b1ed76d9a979..381dcc00cb62 100644
--- a/tools/vm/page-types.c
+++ b/tools/vm/page-types.c
@@ -80,9 +80,10 @@
 #define KPF_SOFTDIRTY		40
 #define KPF_ARCH_2		41
 
-/* [48-] take some arbitrary free slots for expanding overloaded flags
+/* [47-] take some arbitrary free slots for expanding overloaded flags
  * not part of kernel API
  */
+#define KPF_ANON_EXCLUSIVE	47
 #define KPF_READAHEAD		48
 #define KPF_SLOB_FREE		49
 #define KPF_SLUB_FROZEN		50
@@ -138,6 +139,7 @@ static const char * const page_flag_names[] = {
 	[KPF_SOFTDIRTY]		= "f:softdirty",
 	[KPF_ARCH_2]		= "H:arch_2",
 
+	[KPF_ANON_EXCLUSIVE]	= "d:anon_exclusive",
 	[KPF_READAHEAD]		= "I:readahead",
 	[KPF_SLOB_FREE]		= "P:slob_free",
 	[KPF_SLUB_FROZEN]	= "A:slub_frozen",
@@ -472,6 +474,10 @@ static int bit_mask_ok(uint64_t flags)
 
 static uint64_t expand_overloaded_flags(uint64_t flags, uint64_t pme)
 {
+	/* Anonymous pages overload PG_mappedtodisk */
+	if ((flags & BIT(ANON)) && (flags & BIT(MAPPEDTODISK)))
+		flags ^= BIT(MAPPEDTODISK) | BIT(ANON_EXCLUSIVE);
+
 	/* SLOB/SLUB overload several page flags */
 	if (flags & BIT(SLAB)) {
 		if (flags & BIT(PRIVATE))