+ mm-introduce-memdesc_flags_t.patch added to mm-new branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm: introduce memdesc_flags_t
has been added to the -mm mm-new branch.  Its filename is
     mm-introduce-memdesc_flags_t.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-introduce-memdesc_flags_t.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

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   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Subject: mm: introduce memdesc_flags_t
Date: Tue, 5 Aug 2025 18:22:51 +0100

Patch series "Add and use memdesc_flags_t".

At some point struct page will be separated from struct slab and struct
folio.  This is a step towards that by introducing a type for the 'flags'
word of all three structures.  This gives us a certain amount of type
safety by establishing that some of these unsigned longs are different
from other unsigned longs in that they contain things like node ID,
section number and zone number in the upper bits.  That lets us have
functions that can be easily called by anyone who has a slab, folio or
page (but not easily by anyone else) to get the node or zone.

There's going to be some unusual merge problems with this as some odd bits
of the kernel decide they want to print out the flags value or something
similar by writing page->flags and now they'll need to write page->flags.f
instead.  That's most of the churn here.  Maybe we should be removing
these things from the debug output?


This patch (of 11):

Wrap the unsigned long flags in a typedef.  In upcoming patches, this will
provide a strong hint that you can't just pass a random unsigned long to
functions which take this as an argument.

Link: https://lkml.kernel.org/r/20250805172307.1302730-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20250805172307.1302730-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Zi Yan <ziy@nvidia.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/x86/mm/pat/memtype.c       |    6 ++--
 fs/fuse/dev.c                   |    2 -
 fs/gfs2/glops.c                 |    2 -
 fs/jffs2/file.c                 |    4 +--
 fs/nilfs2/page.c                |    2 -
 fs/proc/page.c                  |    4 +--
 fs/ubifs/file.c                 |    6 ++--
 include/linux/mm.h              |   32 ++++++++++++------------
 include/linux/mm_inline.h       |   12 ++++-----
 include/linux/mm_types.h        |    8 ++++--
 include/linux/mmzone.h          |    2 -
 include/linux/page-flags.h      |   40 +++++++++++++++---------------
 include/linux/pgalloc_tag.h     |    7 +++--
 include/trace/events/page_ref.h |    4 +--
 mm/filemap.c                    |    8 +++---
 mm/huge_memory.c                |    4 +--
 mm/memory-failure.c             |   12 ++++-----
 mm/mmzone.c                     |    4 +--
 mm/page_alloc.c                 |   12 ++++-----
 mm/swap.c                       |    8 +++---
 mm/vmscan.c                     |   18 ++++++-------
 mm/workingset.c                 |    2 -
 22 files changed, 102 insertions(+), 97 deletions(-)

--- a/arch/x86/mm/pat/memtype.c~mm-introduce-memdesc_flags_t
+++ a/arch/x86/mm/pat/memtype.c
@@ -126,7 +126,7 @@ __setup("debugpat", pat_debug_setup);
 
 static inline enum page_cache_mode get_page_memtype(struct page *pg)
 {
-	unsigned long pg_flags = pg->flags & _PGMT_MASK;
+	unsigned long pg_flags = pg->flags.f & _PGMT_MASK;
 
 	if (pg_flags == _PGMT_WB)
 		return _PAGE_CACHE_MODE_WB;
@@ -161,10 +161,10 @@ static inline void set_page_memtype(stru
 		break;
 	}
 
-	old_flags = READ_ONCE(pg->flags);
+	old_flags = READ_ONCE(pg->flags.f);
 	do {
 		new_flags = (old_flags & _PGMT_CLEAR_MASK) | memtype_flags;
-	} while (!try_cmpxchg(&pg->flags, &old_flags, new_flags));
+	} while (!try_cmpxchg(&pg->flags.f, &old_flags, new_flags));
 }
 #else
 static inline enum page_cache_mode get_page_memtype(struct page *pg)
--- a/fs/fuse/dev.c~mm-introduce-memdesc_flags_t
+++ a/fs/fuse/dev.c
@@ -935,7 +935,7 @@ static int fuse_check_folio(struct folio
 {
 	if (folio_mapped(folio) ||
 	    folio->mapping != NULL ||
-	    (folio->flags & PAGE_FLAGS_CHECK_AT_PREP &
+	    (folio->flags.f & PAGE_FLAGS_CHECK_AT_PREP &
 	     ~(1 << PG_locked |
 	       1 << PG_referenced |
 	       1 << PG_lru |
--- a/fs/gfs2/glops.c~mm-introduce-memdesc_flags_t
+++ a/fs/gfs2/glops.c
@@ -40,7 +40,7 @@ static void gfs2_ail_error(struct gfs2_g
 	       "AIL buffer %p: blocknr %llu state 0x%08lx mapping %p page "
 	       "state 0x%lx\n",
 	       bh, (unsigned long long)bh->b_blocknr, bh->b_state,
-	       bh->b_folio->mapping, bh->b_folio->flags);
+	       bh->b_folio->mapping, bh->b_folio->flags.f);
 	fs_err(sdp, "AIL glock %u:%llu mapping %p\n",
 	       gl->gl_name.ln_type, gl->gl_name.ln_number,
 	       gfs2_glock2aspace(gl));
--- a/fs/jffs2/file.c~mm-introduce-memdesc_flags_t
+++ a/fs/jffs2/file.c
@@ -230,7 +230,7 @@ static int jffs2_write_begin(const struc
 			goto release_sem;
 		}
 	}
-	jffs2_dbg(1, "end write_begin(). folio->flags %lx\n", folio->flags);
+	jffs2_dbg(1, "end write_begin(). folio->flags %lx\n", folio->flags.f);
 
 release_sem:
 	mutex_unlock(&c->alloc_sem);
@@ -259,7 +259,7 @@ static int jffs2_write_end(const struct
 
 	jffs2_dbg(1, "%s(): ino #%lu, page at 0x%llx, range %d-%d, flags %lx\n",
 		  __func__, inode->i_ino, folio_pos(folio),
-		  start, end, folio->flags);
+		  start, end, folio->flags.f);
 
 	/* We need to avoid deadlock with page_cache_read() in
 	   jffs2_garbage_collect_pass(). So the folio must be
--- a/fs/nilfs2/page.c~mm-introduce-memdesc_flags_t
+++ a/fs/nilfs2/page.c
@@ -167,7 +167,7 @@ void nilfs_folio_bug(struct folio *folio
 	printk(KERN_CRIT "NILFS_FOLIO_BUG(%p): cnt=%d index#=%llu flags=0x%lx "
 	       "mapping=%p ino=%lu\n",
 	       folio, folio_ref_count(folio),
-	       (unsigned long long)folio->index, folio->flags, m, ino);
+	       (unsigned long long)folio->index, folio->flags.f, m, ino);
 
 	head = folio_buffers(folio);
 	if (head) {
--- a/fs/proc/page.c~mm-introduce-memdesc_flags_t
+++ a/fs/proc/page.c
@@ -163,7 +163,7 @@ u64 stable_page_flags(const struct page
 	snapshot_page(&ps, page);
 	folio = &ps.folio_snapshot;
 
-	k = folio->flags;
+	k = folio->flags.f;
 	mapping = (unsigned long)folio->mapping;
 	is_anon = mapping & FOLIO_MAPPING_ANON;
 
@@ -238,7 +238,7 @@ u64 stable_page_flags(const struct page
 	if (u & (1 << KPF_HUGE))
 		u |= kpf_copy_bit(k, KPF_HWPOISON,	PG_hwpoison);
 	else
-		u |= kpf_copy_bit(ps.page_snapshot.flags, KPF_HWPOISON, PG_hwpoison);
+		u |= kpf_copy_bit(ps.page_snapshot.flags.f, KPF_HWPOISON, PG_hwpoison);
 #endif
 
 	u |= kpf_copy_bit(k, KPF_RESERVED,	PG_reserved);
--- a/fs/ubifs/file.c~mm-introduce-memdesc_flags_t
+++ a/fs/ubifs/file.c
@@ -107,7 +107,7 @@ static int do_readpage(struct folio *fol
 	size_t offset = 0;
 
 	dbg_gen("ino %lu, pg %lu, i_size %lld, flags %#lx",
-		inode->i_ino, folio->index, i_size, folio->flags);
+		inode->i_ino, folio->index, i_size, folio->flags.f);
 	ubifs_assert(c, !folio_test_checked(folio));
 	ubifs_assert(c, !folio->private);
 
@@ -600,7 +600,7 @@ static int populate_page(struct ubifs_in
 	pgoff_t end_index;
 
 	dbg_gen("ino %lu, pg %lu, i_size %lld, flags %#lx",
-		inode->i_ino, folio->index, i_size, folio->flags);
+		inode->i_ino, folio->index, i_size, folio->flags.f);
 
 	end_index = (i_size - 1) >> PAGE_SHIFT;
 	if (!i_size || folio->index > end_index) {
@@ -988,7 +988,7 @@ static int ubifs_writepage(struct folio
 	int err, len = folio_size(folio);
 
 	dbg_gen("ino %lu, pg %lu, pg flags %#lx",
-		inode->i_ino, folio->index, folio->flags);
+		inode->i_ino, folio->index, folio->flags.f);
 	ubifs_assert(c, folio->private != NULL);
 
 	/* Is the folio fully outside @i_size? (truncate in progress) */
--- a/include/linux/mm.h~mm-introduce-memdesc_flags_t
+++ a/include/linux/mm.h
@@ -1024,7 +1024,7 @@ static inline unsigned int compound_orde
 {
 	struct folio *folio = (struct folio *)page;
 
-	if (!test_bit(PG_head, &folio->flags))
+	if (!test_bit(PG_head, &folio->flags.f))
 		return 0;
 	return folio_large_order(folio);
 }
@@ -1554,7 +1554,7 @@ static inline bool is_nommu_shared_mappi
  */
 static inline int page_zone_id(struct page *page)
 {
-	return (page->flags >> ZONEID_PGSHIFT) & ZONEID_MASK;
+	return (page->flags.f >> ZONEID_PGSHIFT) & ZONEID_MASK;
 }
 
 #ifdef NODE_NOT_IN_PAGE_FLAGS
@@ -1562,7 +1562,7 @@ int page_to_nid(const struct page *page)
 #else
 static inline int page_to_nid(const struct page *page)
 {
-	return (PF_POISONED_CHECK(page)->flags >> NODES_PGSHIFT) & NODES_MASK;
+	return (PF_POISONED_CHECK(page)->flags.f >> NODES_PGSHIFT) & NODES_MASK;
 }
 #endif
 
@@ -1637,14 +1637,14 @@ static inline void page_cpupid_reset_las
 #else
 static inline int folio_last_cpupid(struct folio *folio)
 {
-	return (folio->flags >> LAST_CPUPID_PGSHIFT) & LAST_CPUPID_MASK;
+	return (folio->flags.f >> LAST_CPUPID_PGSHIFT) & LAST_CPUPID_MASK;
 }
 
 int folio_xchg_last_cpupid(struct folio *folio, int cpupid);
 
 static inline void page_cpupid_reset_last(struct page *page)
 {
-	page->flags |= LAST_CPUPID_MASK << LAST_CPUPID_PGSHIFT;
+	page->flags.f |= LAST_CPUPID_MASK << LAST_CPUPID_PGSHIFT;
 }
 #endif /* LAST_CPUPID_NOT_IN_PAGE_FLAGS */
 
@@ -1740,7 +1740,7 @@ static inline u8 page_kasan_tag(const st
 	u8 tag = KASAN_TAG_KERNEL;
 
 	if (kasan_enabled()) {
-		tag = (page->flags >> KASAN_TAG_PGSHIFT) & KASAN_TAG_MASK;
+		tag = (page->flags.f >> KASAN_TAG_PGSHIFT) & KASAN_TAG_MASK;
 		tag ^= 0xff;
 	}
 
@@ -1755,12 +1755,12 @@ static inline void page_kasan_tag_set(st
 		return;
 
 	tag ^= 0xff;
-	old_flags = READ_ONCE(page->flags);
+	old_flags = READ_ONCE(page->flags.f);
 	do {
 		flags = old_flags;
 		flags &= ~(KASAN_TAG_MASK << KASAN_TAG_PGSHIFT);
 		flags |= (tag & KASAN_TAG_MASK) << KASAN_TAG_PGSHIFT;
-	} while (unlikely(!try_cmpxchg(&page->flags, &old_flags, flags)));
+	} while (unlikely(!try_cmpxchg(&page->flags.f, &old_flags, flags)));
 }
 
 static inline void page_kasan_tag_reset(struct page *page)
@@ -1804,13 +1804,13 @@ static inline pg_data_t *folio_pgdat(con
 #ifdef SECTION_IN_PAGE_FLAGS
 static inline void set_page_section(struct page *page, unsigned long section)
 {
-	page->flags &= ~(SECTIONS_MASK << SECTIONS_PGSHIFT);
-	page->flags |= (section & SECTIONS_MASK) << SECTIONS_PGSHIFT;
+	page->flags.f &= ~(SECTIONS_MASK << SECTIONS_PGSHIFT);
+	page->flags.f |= (section & SECTIONS_MASK) << SECTIONS_PGSHIFT;
 }
 
 static inline unsigned long page_to_section(const struct page *page)
 {
-	return (page->flags >> SECTIONS_PGSHIFT) & SECTIONS_MASK;
+	return (page->flags.f >> SECTIONS_PGSHIFT) & SECTIONS_MASK;
 }
 #endif
 
@@ -2015,14 +2015,14 @@ static inline bool folio_is_longterm_pin
 
 static inline void set_page_zone(struct page *page, enum zone_type zone)
 {
-	page->flags &= ~(ZONES_MASK << ZONES_PGSHIFT);
-	page->flags |= (zone & ZONES_MASK) << ZONES_PGSHIFT;
+	page->flags.f &= ~(ZONES_MASK << ZONES_PGSHIFT);
+	page->flags.f |= (zone & ZONES_MASK) << ZONES_PGSHIFT;
 }
 
 static inline void set_page_node(struct page *page, unsigned long node)
 {
-	page->flags &= ~(NODES_MASK << NODES_PGSHIFT);
-	page->flags |= (node & NODES_MASK) << NODES_PGSHIFT;
+	page->flags.f &= ~(NODES_MASK << NODES_PGSHIFT);
+	page->flags.f |= (node & NODES_MASK) << NODES_PGSHIFT;
 }
 
 static inline void set_page_links(struct page *page, enum zone_type zone,
@@ -2064,7 +2064,7 @@ static inline long compound_nr(struct pa
 {
 	struct folio *folio = (struct folio *)page;
 
-	if (!test_bit(PG_head, &folio->flags))
+	if (!test_bit(PG_head, &folio->flags.f))
 		return 1;
 	return folio_large_nr_pages(folio);
 }
--- a/include/linux/mm_inline.h~mm-introduce-memdesc_flags_t
+++ a/include/linux/mm_inline.h
@@ -143,7 +143,7 @@ static inline int lru_tier_from_refs(int
 
 static inline int folio_lru_refs(struct folio *folio)
 {
-	unsigned long flags = READ_ONCE(folio->flags);
+	unsigned long flags = READ_ONCE(folio->flags.f);
 
 	if (!(flags & BIT(PG_referenced)))
 		return 0;
@@ -156,7 +156,7 @@ static inline int folio_lru_refs(struct
 
 static inline int folio_lru_gen(struct folio *folio)
 {
-	unsigned long flags = READ_ONCE(folio->flags);
+	unsigned long flags = READ_ONCE(folio->flags.f);
 
 	return ((flags & LRU_GEN_MASK) >> LRU_GEN_PGOFF) - 1;
 }
@@ -268,7 +268,7 @@ static inline bool lru_gen_add_folio(str
 	gen = lru_gen_from_seq(seq);
 	flags = (gen + 1UL) << LRU_GEN_PGOFF;
 	/* see the comment on MIN_NR_GENS about PG_active */
-	set_mask_bits(&folio->flags, LRU_GEN_MASK | BIT(PG_active), flags);
+	set_mask_bits(&folio->flags.f, LRU_GEN_MASK | BIT(PG_active), flags);
 
 	lru_gen_update_size(lruvec, folio, -1, gen);
 	/* for folio_rotate_reclaimable() */
@@ -293,7 +293,7 @@ static inline bool lru_gen_del_folio(str
 
 	/* for folio_migrate_flags() */
 	flags = !reclaiming && lru_gen_is_active(lruvec, gen) ? BIT(PG_active) : 0;
-	flags = set_mask_bits(&folio->flags, LRU_GEN_MASK, flags);
+	flags = set_mask_bits(&folio->flags.f, LRU_GEN_MASK, flags);
 	gen = ((flags & LRU_GEN_MASK) >> LRU_GEN_PGOFF) - 1;
 
 	lru_gen_update_size(lruvec, folio, gen, -1);
@@ -304,9 +304,9 @@ static inline bool lru_gen_del_folio(str
 
 static inline void folio_migrate_refs(struct folio *new, struct folio *old)
 {
-	unsigned long refs = READ_ONCE(old->flags) & LRU_REFS_MASK;
+	unsigned long refs = READ_ONCE(old->flags.f) & LRU_REFS_MASK;
 
-	set_mask_bits(&new->flags, LRU_REFS_MASK, refs);
+	set_mask_bits(&new->flags.f, LRU_REFS_MASK, refs);
 }
 #else /* !CONFIG_LRU_GEN */
 
--- a/include/linux/mm_types.h~mm-introduce-memdesc_flags_t
+++ a/include/linux/mm_types.h
@@ -34,6 +34,10 @@ struct address_space;
 struct futex_private_hash;
 struct mem_cgroup;
 
+typedef struct {
+	unsigned long f;
+} memdesc_flags_t;
+
 /*
  * Each physical page in the system has a struct page associated with
  * it to keep track of whatever it is we are using the page for at the
@@ -72,7 +76,7 @@ struct mem_cgroup;
 #endif
 
 struct page {
-	unsigned long flags;		/* Atomic flags, some possibly
+	memdesc_flags_t flags;		/* Atomic flags, some possibly
 					 * updated asynchronously */
 	/*
 	 * Five words (20/40 bytes) are available in this union.
@@ -383,7 +387,7 @@ struct folio {
 	union {
 		struct {
 	/* public: */
-			unsigned long flags;
+			memdesc_flags_t flags;
 			union {
 				struct list_head lru;
 	/* private: avoid cluttering the output */
--- a/include/linux/mmzone.h~mm-introduce-memdesc_flags_t
+++ a/include/linux/mmzone.h
@@ -1186,7 +1186,7 @@ static inline bool zone_is_empty(struct
 static inline enum zone_type page_zonenum(const struct page *page)
 {
 	ASSERT_EXCLUSIVE_BITS(page->flags, ZONES_MASK << ZONES_PGSHIFT);
-	return (page->flags >> ZONES_PGSHIFT) & ZONES_MASK;
+	return (page->flags.f >> ZONES_PGSHIFT) & ZONES_MASK;
 }
 
 static inline enum zone_type folio_zonenum(const struct folio *folio)
--- a/include/linux/page-flags.h~mm-introduce-memdesc_flags_t
+++ a/include/linux/page-flags.h
@@ -217,7 +217,7 @@ static __always_inline const struct page
 	 * cold cacheline in some cases.
 	 */
 	if (IS_ALIGNED((unsigned long)page, PAGE_SIZE) &&
-	    test_bit(PG_head, &page->flags)) {
+	    test_bit(PG_head, &page->flags.f)) {
 		/*
 		 * We can safely access the field of the @page[1] with PG_head
 		 * because the @page is a compound page composed with at least
@@ -325,14 +325,14 @@ static __always_inline int PageTail(cons
 
 static __always_inline int PageCompound(const struct page *page)
 {
-	return test_bit(PG_head, &page->flags) ||
+	return test_bit(PG_head, &page->flags.f) ||
 	       READ_ONCE(page->compound_head) & 1;
 }
 
 #define	PAGE_POISON_PATTERN	-1l
 static inline int PagePoisoned(const struct page *page)
 {
-	return READ_ONCE(page->flags) == PAGE_POISON_PATTERN;
+	return READ_ONCE(page->flags.f) == PAGE_POISON_PATTERN;
 }
 
 #ifdef CONFIG_DEBUG_VM
@@ -349,8 +349,8 @@ static const unsigned long *const_folio_
 	const struct page *page = &folio->page;
 
 	VM_BUG_ON_PGFLAGS(page->compound_head & 1, page);
-	VM_BUG_ON_PGFLAGS(n > 0 && !test_bit(PG_head, &page->flags), page);
-	return &page[n].flags;
+	VM_BUG_ON_PGFLAGS(n > 0 && !test_bit(PG_head, &page->flags.f), page);
+	return &page[n].flags.f;
 }
 
 static unsigned long *folio_flags(struct folio *folio, unsigned n)
@@ -358,8 +358,8 @@ static unsigned long *folio_flags(struct
 	struct page *page = &folio->page;
 
 	VM_BUG_ON_PGFLAGS(page->compound_head & 1, page);
-	VM_BUG_ON_PGFLAGS(n > 0 && !test_bit(PG_head, &page->flags), page);
-	return &page[n].flags;
+	VM_BUG_ON_PGFLAGS(n > 0 && !test_bit(PG_head, &page->flags.f), page);
+	return &page[n].flags.f;
 }
 
 /*
@@ -449,37 +449,37 @@ FOLIO_CLEAR_FLAG(name, page)
 #define TESTPAGEFLAG(uname, lname, policy)				\
 FOLIO_TEST_FLAG(lname, FOLIO_##policy)					\
 static __always_inline int Page##uname(const struct page *page)		\
-{ return test_bit(PG_##lname, &policy(page, 0)->flags); }
+{ return test_bit(PG_##lname, &policy(page, 0)->flags.f); }
 
 #define SETPAGEFLAG(uname, lname, policy)				\
 FOLIO_SET_FLAG(lname, FOLIO_##policy)					\
 static __always_inline void SetPage##uname(struct page *page)		\
-{ set_bit(PG_##lname, &policy(page, 1)->flags); }
+{ set_bit(PG_##lname, &policy(page, 1)->flags.f); }
 
 #define CLEARPAGEFLAG(uname, lname, policy)				\
 FOLIO_CLEAR_FLAG(lname, FOLIO_##policy)					\
 static __always_inline void ClearPage##uname(struct page *page)		\
-{ clear_bit(PG_##lname, &policy(page, 1)->flags); }
+{ clear_bit(PG_##lname, &policy(page, 1)->flags.f); }
 
 #define __SETPAGEFLAG(uname, lname, policy)				\
 __FOLIO_SET_FLAG(lname, FOLIO_##policy)					\
 static __always_inline void __SetPage##uname(struct page *page)		\
-{ __set_bit(PG_##lname, &policy(page, 1)->flags); }
+{ __set_bit(PG_##lname, &policy(page, 1)->flags.f); }
 
 #define __CLEARPAGEFLAG(uname, lname, policy)				\
 __FOLIO_CLEAR_FLAG(lname, FOLIO_##policy)				\
 static __always_inline void __ClearPage##uname(struct page *page)	\
-{ __clear_bit(PG_##lname, &policy(page, 1)->flags); }
+{ __clear_bit(PG_##lname, &policy(page, 1)->flags.f); }
 
 #define TESTSETFLAG(uname, lname, policy)				\
 FOLIO_TEST_SET_FLAG(lname, FOLIO_##policy)				\
 static __always_inline int TestSetPage##uname(struct page *page)	\
-{ return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
+{ return test_and_set_bit(PG_##lname, &policy(page, 1)->flags.f); }
 
 #define TESTCLEARFLAG(uname, lname, policy)				\
 FOLIO_TEST_CLEAR_FLAG(lname, FOLIO_##policy)				\
 static __always_inline int TestClearPage##uname(struct page *page)	\
-{ return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
+{ return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags.f); }
 
 #define PAGEFLAG(uname, lname, policy)					\
 	TESTPAGEFLAG(uname, lname, policy)				\
@@ -846,7 +846,7 @@ static __always_inline bool folio_test_h
 static __always_inline int PageHead(const struct page *page)
 {
 	PF_POISONED_CHECK(page);
-	return test_bit(PG_head, &page->flags) && !page_is_fake_head(page);
+	return test_bit(PG_head, &page->flags.f) && !page_is_fake_head(page);
 }
 
 __SETPAGEFLAG(Head, head, PF_ANY)
@@ -1170,28 +1170,28 @@ static __always_inline int PageAnonExclu
 	 */
 	if (PageHuge(page))
 		page = compound_head(page);
-	return test_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
+	return test_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags.f);
 }
 
 static __always_inline void SetPageAnonExclusive(struct page *page)
 {
 	VM_BUG_ON_PGFLAGS(!PageAnonNotKsm(page), page);
 	VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
-	set_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
+	set_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags.f);
 }
 
 static __always_inline void ClearPageAnonExclusive(struct page *page)
 {
 	VM_BUG_ON_PGFLAGS(!PageAnonNotKsm(page), page);
 	VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
-	clear_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
+	clear_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags.f);
 }
 
 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);
+	__clear_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags.f);
 }
 
 #ifdef CONFIG_MMU
@@ -1241,7 +1241,7 @@ static __always_inline void __ClearPageA
  */
 static inline int folio_has_private(const struct folio *folio)
 {
-	return !!(folio->flags & PAGE_FLAGS_PRIVATE);
+	return !!(folio->flags.f & PAGE_FLAGS_PRIVATE);
 }
 
 #undef PF_ANY
--- a/include/linux/pgalloc_tag.h~mm-introduce-memdesc_flags_t
+++ a/include/linux/pgalloc_tag.h
@@ -107,7 +107,8 @@ static inline bool get_page_tag_ref(stru
 	if (static_key_enabled(&mem_profiling_compressed)) {
 		pgalloc_tag_idx idx;
 
-		idx = (page->flags >> alloc_tag_ref_offs) & alloc_tag_ref_mask;
+		idx = (page->flags.f >> alloc_tag_ref_offs) &
+			alloc_tag_ref_mask;
 		idx_to_ref(idx, ref);
 		handle->page = page;
 	} else {
@@ -149,11 +150,11 @@ static inline void update_page_tag_ref(u
 		idx = (unsigned long)ref_to_idx(ref);
 		idx = (idx & alloc_tag_ref_mask) << alloc_tag_ref_offs;
 		do {
-			old_flags = READ_ONCE(page->flags);
+			old_flags = READ_ONCE(page->flags.f);
 			flags = old_flags;
 			flags &= ~(alloc_tag_ref_mask << alloc_tag_ref_offs);
 			flags |= idx;
-		} while (unlikely(!try_cmpxchg(&page->flags, &old_flags, flags)));
+		} while (unlikely(!try_cmpxchg(&page->flags.f, &old_flags, flags)));
 	} else {
 		if (WARN_ON(!handle.ref || !ref))
 			return;
--- a/include/trace/events/page_ref.h~mm-introduce-memdesc_flags_t
+++ a/include/trace/events/page_ref.h
@@ -28,7 +28,7 @@ DECLARE_EVENT_CLASS(page_ref_mod_templat
 
 	TP_fast_assign(
 		__entry->pfn = page_to_pfn(page);
-		__entry->flags = page->flags;
+		__entry->flags = page->flags.f;
 		__entry->count = page_ref_count(page);
 		__entry->mapcount = atomic_read(&page->_mapcount);
 		__entry->mapping = page->mapping;
@@ -77,7 +77,7 @@ DECLARE_EVENT_CLASS(page_ref_mod_and_tes
 
 	TP_fast_assign(
 		__entry->pfn = page_to_pfn(page);
-		__entry->flags = page->flags;
+		__entry->flags = page->flags.f;
 		__entry->count = page_ref_count(page);
 		__entry->mapcount = atomic_read(&page->_mapcount);
 		__entry->mapping = page->mapping;
--- a/mm/filemap.c~mm-introduce-memdesc_flags_t
+++ a/mm/filemap.c
@@ -1140,10 +1140,10 @@ static int wake_page_function(wait_queue
 	 */
 	flags = wait->flags;
 	if (flags & WQ_FLAG_EXCLUSIVE) {
-		if (test_bit(key->bit_nr, &key->folio->flags))
+		if (test_bit(key->bit_nr, &key->folio->flags.f))
 			return -1;
 		if (flags & WQ_FLAG_CUSTOM) {
-			if (test_and_set_bit(key->bit_nr, &key->folio->flags))
+			if (test_and_set_bit(key->bit_nr, &key->folio->flags.f))
 				return -1;
 			flags |= WQ_FLAG_DONE;
 		}
@@ -1226,9 +1226,9 @@ static inline bool folio_trylock_flag(st
 					struct wait_queue_entry *wait)
 {
 	if (wait->flags & WQ_FLAG_EXCLUSIVE) {
-		if (test_and_set_bit(bit_nr, &folio->flags))
+		if (test_and_set_bit(bit_nr, &folio->flags.f))
 			return false;
-	} else if (test_bit(bit_nr, &folio->flags))
+	} else if (test_bit(bit_nr, &folio->flags.f))
 		return false;
 
 	wait->flags |= WQ_FLAG_WOKEN | WQ_FLAG_DONE;
--- a/mm/huge_memory.c~mm-introduce-memdesc_flags_t
+++ a/mm/huge_memory.c
@@ -3303,8 +3303,8 @@ static void __split_folio_to_order(struc
 		 * unreferenced sub-pages of an anonymous THP: we can simply drop
 		 * PG_anon_exclusive (-> PG_mappedtodisk) for these here.
 		 */
-		new_folio->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
-		new_folio->flags |= (folio->flags &
+		new_folio->flags.f &= ~PAGE_FLAGS_CHECK_AT_PREP;
+		new_folio->flags.f |= (folio->flags.f &
 				((1L << PG_referenced) |
 				 (1L << PG_swapbacked) |
 				 (1L << PG_swapcache) |
--- a/mm/memory-failure.c~mm-introduce-memdesc_flags_t
+++ a/mm/memory-failure.c
@@ -1707,10 +1707,10 @@ static int identify_page_state(unsigned
 	 * carried out only if the first check can't determine the page status.
 	 */
 	for (ps = error_states;; ps++)
-		if ((p->flags & ps->mask) == ps->res)
+		if ((p->flags.f & ps->mask) == ps->res)
 			break;
 
-	page_flags |= (p->flags & (1UL << PG_dirty));
+	page_flags |= (p->flags.f & (1UL << PG_dirty));
 
 	if (!ps->mask)
 		for (ps = error_states;; ps++)
@@ -2137,7 +2137,7 @@ retry:
 		return action_result(pfn, MF_MSG_FREE_HUGE, res);
 	}
 
-	page_flags = folio->flags;
+	page_flags = folio->flags.f;
 
 	if (!hwpoison_user_mappings(folio, p, pfn, flags)) {
 		folio_unlock(folio);
@@ -2398,7 +2398,7 @@ try_again:
 	 * folio_remove_rmap_*() in try_to_unmap_one(). So to determine page
 	 * status correctly, we save a copy of the page flags at this time.
 	 */
-	page_flags = folio->flags;
+	page_flags = folio->flags.f;
 
 	/*
 	 * __munlock_folio() may clear a writeback folio's LRU flag without
@@ -2744,13 +2744,13 @@ static int soft_offline_in_use_page(stru
 				putback_movable_pages(&pagelist);
 
 			pr_info("%#lx: %s migration failed %ld, type %pGp\n",
-				pfn, msg_page[huge], ret, &page->flags);
+				pfn, msg_page[huge], ret, &page->flags.f);
 			if (ret > 0)
 				ret = -EBUSY;
 		}
 	} else {
 		pr_info("%#lx: %s isolation failed, page count %d, type %pGp\n",
-			pfn, msg_page[huge], page_count(page), &page->flags);
+			pfn, msg_page[huge], page_count(page), &page->flags.f);
 		ret = -EBUSY;
 	}
 	return ret;
--- a/mm/mmzone.c~mm-introduce-memdesc_flags_t
+++ a/mm/mmzone.c
@@ -99,14 +99,14 @@ int folio_xchg_last_cpupid(struct folio
 	unsigned long old_flags, flags;
 	int last_cpupid;
 
-	old_flags = READ_ONCE(folio->flags);
+	old_flags = READ_ONCE(folio->flags.f);
 	do {
 		flags = old_flags;
 		last_cpupid = (flags >> LAST_CPUPID_PGSHIFT) & LAST_CPUPID_MASK;
 
 		flags &= ~(LAST_CPUPID_MASK << LAST_CPUPID_PGSHIFT);
 		flags |= (cpupid & LAST_CPUPID_MASK) << LAST_CPUPID_PGSHIFT;
-	} while (unlikely(!try_cmpxchg(&folio->flags, &old_flags, flags)));
+	} while (unlikely(!try_cmpxchg(&folio->flags.f, &old_flags, flags)));
 
 	return last_cpupid;
 }
--- a/mm/page_alloc.c~mm-introduce-memdesc_flags_t
+++ a/mm/page_alloc.c
@@ -950,7 +950,7 @@ static inline void __free_one_page(struc
 	bool to_tail;
 
 	VM_BUG_ON(!zone_is_initialized(zone));
-	VM_BUG_ON_PAGE(page->flags & PAGE_FLAGS_CHECK_AT_PREP, page);
+	VM_BUG_ON_PAGE(page->flags.f & PAGE_FLAGS_CHECK_AT_PREP, page);
 
 	VM_BUG_ON(migratetype == -1);
 	VM_BUG_ON_PAGE(pfn & ((1 << order) - 1), page);
@@ -1043,7 +1043,7 @@ static inline bool page_expected_state(s
 			page->memcg_data |
 #endif
 			page_pool_page_is_pp(page) |
-			(page->flags & check_flags)))
+			(page->flags.f & check_flags)))
 		return false;
 
 	return true;
@@ -1059,7 +1059,7 @@ static const char *page_bad_reason(struc
 		bad_reason = "non-NULL mapping";
 	if (unlikely(page_ref_count(page) != 0))
 		bad_reason = "nonzero _refcount";
-	if (unlikely(page->flags & flags)) {
+	if (unlikely(page->flags.f & flags)) {
 		if (flags == PAGE_FLAGS_CHECK_AT_PREP)
 			bad_reason = "PAGE_FLAGS_CHECK_AT_PREP flag(s) set";
 		else
@@ -1358,7 +1358,7 @@ __always_inline bool free_pages_prepare(
 		int i;
 
 		if (compound) {
-			page[1].flags &= ~PAGE_FLAGS_SECOND;
+			page[1].flags.f &= ~PAGE_FLAGS_SECOND;
 #ifdef NR_PAGES_IN_LARGE_FOLIO
 			folio->_nr_pages = 0;
 #endif
@@ -1372,7 +1372,7 @@ __always_inline bool free_pages_prepare(
 					continue;
 				}
 			}
-			(page + i)->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
+			(page + i)->flags.f &= ~PAGE_FLAGS_CHECK_AT_PREP;
 		}
 	}
 	if (folio_test_anon(folio)) {
@@ -1391,7 +1391,7 @@ __always_inline bool free_pages_prepare(
 	}
 
 	page_cpupid_reset_last(page);
-	page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
+	page->flags.f &= ~PAGE_FLAGS_CHECK_AT_PREP;
 	reset_page_owner(page, order);
 	page_table_check_free(page, order);
 	pgalloc_tag_sub(page, 1 << order);
--- a/mm/swap.c~mm-introduce-memdesc_flags_t
+++ a/mm/swap.c
@@ -387,14 +387,14 @@ static void __lru_cache_activate_folio(s
 
 static void lru_gen_inc_refs(struct folio *folio)
 {
-	unsigned long new_flags, old_flags = READ_ONCE(folio->flags);
+	unsigned long new_flags, old_flags = READ_ONCE(folio->flags.f);
 
 	if (folio_test_unevictable(folio))
 		return;
 
 	/* see the comment on LRU_REFS_FLAGS */
 	if (!folio_test_referenced(folio)) {
-		set_mask_bits(&folio->flags, LRU_REFS_MASK, BIT(PG_referenced));
+		set_mask_bits(&folio->flags.f, LRU_REFS_MASK, BIT(PG_referenced));
 		return;
 	}
 
@@ -406,7 +406,7 @@ static void lru_gen_inc_refs(struct foli
 		}
 
 		new_flags = old_flags + BIT(LRU_REFS_PGOFF);
-	} while (!try_cmpxchg(&folio->flags, &old_flags, new_flags));
+	} while (!try_cmpxchg(&folio->flags.f, &old_flags, new_flags));
 }
 
 static bool lru_gen_clear_refs(struct folio *folio)
@@ -418,7 +418,7 @@ static bool lru_gen_clear_refs(struct fo
 	if (gen < 0)
 		return true;
 
-	set_mask_bits(&folio->flags, LRU_REFS_FLAGS | BIT(PG_workingset), 0);
+	set_mask_bits(&folio->flags.f, LRU_REFS_FLAGS | BIT(PG_workingset), 0);
 
 	lrugen = &folio_lruvec(folio)->lrugen;
 	/* whether can do without shuffling under the LRU lock */
--- a/mm/vmscan.c~mm-introduce-memdesc_flags_t
+++ a/mm/vmscan.c
@@ -888,11 +888,11 @@ static bool lru_gen_set_refs(struct foli
 {
 	/* see the comment on LRU_REFS_FLAGS */
 	if (!folio_test_referenced(folio) && !folio_test_workingset(folio)) {
-		set_mask_bits(&folio->flags, LRU_REFS_MASK, BIT(PG_referenced));
+		set_mask_bits(&folio->flags.f, LRU_REFS_MASK, BIT(PG_referenced));
 		return false;
 	}
 
-	set_mask_bits(&folio->flags, LRU_REFS_FLAGS, BIT(PG_workingset));
+	set_mask_bits(&folio->flags.f, LRU_REFS_FLAGS, BIT(PG_workingset));
 	return true;
 }
 #else
@@ -3257,13 +3257,13 @@ static bool positive_ctrl_err(struct ctr
 /* promote pages accessed through page tables */
 static int folio_update_gen(struct folio *folio, int gen)
 {
-	unsigned long new_flags, old_flags = READ_ONCE(folio->flags);
+	unsigned long new_flags, old_flags = READ_ONCE(folio->flags.f);
 
 	VM_WARN_ON_ONCE(gen >= MAX_NR_GENS);
 
 	/* see the comment on LRU_REFS_FLAGS */
 	if (!folio_test_referenced(folio) && !folio_test_workingset(folio)) {
-		set_mask_bits(&folio->flags, LRU_REFS_MASK, BIT(PG_referenced));
+		set_mask_bits(&folio->flags.f, LRU_REFS_MASK, BIT(PG_referenced));
 		return -1;
 	}
 
@@ -3274,7 +3274,7 @@ static int folio_update_gen(struct folio
 
 		new_flags = old_flags & ~(LRU_GEN_MASK | LRU_REFS_FLAGS);
 		new_flags |= ((gen + 1UL) << LRU_GEN_PGOFF) | BIT(PG_workingset);
-	} while (!try_cmpxchg(&folio->flags, &old_flags, new_flags));
+	} while (!try_cmpxchg(&folio->flags.f, &old_flags, new_flags));
 
 	return ((old_flags & LRU_GEN_MASK) >> LRU_GEN_PGOFF) - 1;
 }
@@ -3285,7 +3285,7 @@ static int folio_inc_gen(struct lruvec *
 	int type = folio_is_file_lru(folio);
 	struct lru_gen_folio *lrugen = &lruvec->lrugen;
 	int new_gen, old_gen = lru_gen_from_seq(lrugen->min_seq[type]);
-	unsigned long new_flags, old_flags = READ_ONCE(folio->flags);
+	unsigned long new_flags, old_flags = READ_ONCE(folio->flags.f);
 
 	VM_WARN_ON_ONCE_FOLIO(!(old_flags & LRU_GEN_MASK), folio);
 
@@ -3302,7 +3302,7 @@ static int folio_inc_gen(struct lruvec *
 		/* for folio_end_writeback() */
 		if (reclaiming)
 			new_flags |= BIT(PG_reclaim);
-	} while (!try_cmpxchg(&folio->flags, &old_flags, new_flags));
+	} while (!try_cmpxchg(&folio->flags.f, &old_flags, new_flags));
 
 	lru_gen_update_size(lruvec, folio, old_gen, new_gen);
 
@@ -4553,7 +4553,7 @@ static bool isolate_folio(struct lruvec
 
 	/* see the comment on LRU_REFS_FLAGS */
 	if (!folio_test_referenced(folio))
-		set_mask_bits(&folio->flags, LRU_REFS_MASK, 0);
+		set_mask_bits(&folio->flags.f, LRU_REFS_MASK, 0);
 
 	/* for shrink_folio_list() */
 	folio_clear_reclaim(folio);
@@ -4766,7 +4766,7 @@ retry:
 
 		/* don't add rejected folios to the oldest generation */
 		if (lru_gen_folio_seq(lruvec, folio, false) == min_seq[type])
-			set_mask_bits(&folio->flags, LRU_REFS_FLAGS, BIT(PG_active));
+			set_mask_bits(&folio->flags.f, LRU_REFS_FLAGS, BIT(PG_active));
 	}
 
 	spin_lock_irq(&lruvec->lru_lock);
--- a/mm/workingset.c~mm-introduce-memdesc_flags_t
+++ a/mm/workingset.c
@@ -318,7 +318,7 @@ static void lru_gen_refault(struct folio
 		folio_set_workingset(folio);
 		mod_lruvec_state(lruvec, WORKINGSET_RESTORE_BASE + type, delta);
 	} else
-		set_mask_bits(&folio->flags, LRU_REFS_MASK, (refs - 1UL) << LRU_REFS_PGOFF);
+		set_mask_bits(&folio->flags.f, LRU_REFS_MASK, (refs - 1UL) << LRU_REFS_PGOFF);
 unlock:
 	rcu_read_unlock();
 }
_

Patches currently in -mm which might be from willy@infradead.org are

mm-introduce-memdesc_flags_t.patch
mm-convert-page_to_section-to-memdesc_section.patch
mm-introduce-memdesc_nid.patch
mm-introduce-memdesc_zonenum.patch
slab-use-memdesc_flags_t.patch
slab-use-memdesc_nid.patch
mm-introduce-memdesc_is_zone_device.patch
mm-reimplement-folio_is_device_private.patch
mm-reimplement-folio_is_device_coherent.patch
mm-reimplement-folio_is_fsdax.patch
mm-add-folio_is_pci_p2pdma.patch