Merge branch 'mm-hotfixes-stable' into mm-stable to pick up "mm: fix

crashes from deferred split racing folio migration", needed by "mm:
migrate: split folio_migrate_mapping()".

.mailmap

@@ -384,6 +384,7 @@ Li Yang <leoyang.li@nxp.com> <leoli@freescale.com>
 Li Yang <leoyang.li@nxp.com> <leo@zh-kernel.org>
 Lior David <quic_liord@quicinc.com> <liord@codeaurora.org>
 Lorenzo Pieralisi <lpieralisi@kernel.org> <lorenzo.pieralisi@arm.com>
+Lorenzo Stoakes <lorenzo.stoakes@oracle.com> <lstoakes@gmail.com>
 Luca Ceresoli <luca.ceresoli@bootlin.com> <luca@lucaceresoli.net>
 Lukasz Luba <lukasz.luba@arm.com> <l.luba@partner.samsung.com>
 Luo Jie <quic_luoj@quicinc.com> <luoj@codeaurora.org>

MAINTAINERS

@@ -14476,7 +14476,7 @@ MEMORY MAPPING
 M:	Andrew Morton <akpm@linux-foundation.org>
 R:	Liam R. Howlett <Liam.Howlett@oracle.com>
 R:	Vlastimil Babka <vbabka@suse.cz>
-R:	Lorenzo Stoakes <lstoakes@gmail.com>
+R:	Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
 L:	linux-mm@kvack.org
 S:	Maintained
 W:	http://www.linux-mm.org

fs/nilfs2/dir.c

@@ -383,11 +383,39 @@ found:
 
 struct nilfs_dir_entry *nilfs_dotdot(struct inode *dir, struct folio **foliop)
 {
-	struct nilfs_dir_entry *de = nilfs_get_folio(dir, 0, foliop);
+	struct folio *folio;
+	struct nilfs_dir_entry *de, *next_de;
+	size_t limit;
+	char *msg;
 
+	de = nilfs_get_folio(dir, 0, &folio);
 	if (IS_ERR(de))
 		return NULL;
-	return nilfs_next_entry(de);
+
+	limit = nilfs_last_byte(dir, 0);  /* is a multiple of chunk size */
+	if (unlikely(!limit || le64_to_cpu(de->inode) != dir->i_ino ||
+		     !nilfs_match(1, ".", de))) {
+		msg = "missing '.'";
+		goto fail;
+	}
+
+	next_de = nilfs_next_entry(de);
+	/*
+	 * If "next_de" has not reached the end of the chunk, there is
+	 * at least one more record.  Check whether it matches "..".
+	 */
+	if (unlikely((char *)next_de == (char *)de + nilfs_chunk_size(dir) ||
+		     !nilfs_match(2, "..", next_de))) {
+		msg = "missing '..'";
+		goto fail;
+	}
+	*foliop = folio;
+	return next_de;
+
+fail:
+	nilfs_error(dir->i_sb, "directory #%lu %s", dir->i_ino, msg);
+	folio_release_kmap(folio, de);
+	return NULL;
 }
 
 ino_t nilfs_inode_by_name(struct inode *dir, const struct qstr *qstr)

fs/userfaultfd.c

@@ -2057,7 +2057,7 @@ static int userfaultfd_api(struct userfaultfd_ctx *ctx,
 		goto out;
 	features = uffdio_api.features;
 	ret = -EINVAL;
-	if (uffdio_api.api != UFFD_API || (features & ~UFFD_API_FEATURES))
+	if (uffdio_api.api != UFFD_API)
 		goto err_out;
 	ret = -EPERM;
 	if ((features & UFFD_FEATURE_EVENT_FORK) && !capable(CAP_SYS_PTRACE))
@@ -2081,6 +2081,11 @@ static int userfaultfd_api(struct userfaultfd_ctx *ctx,
 	uffdio_api.features &= ~UFFD_FEATURE_WP_UNPOPULATED;
 	uffdio_api.features &= ~UFFD_FEATURE_WP_ASYNC;
 #endif
+
+	ret = -EINVAL;
+	if (features & ~uffdio_api.features)
+		goto err_out;
+
 	uffdio_api.ioctls = UFFD_API_IOCTLS;
 	ret = -EFAULT;
 	if (copy_to_user(buf, &uffdio_api, sizeof(uffdio_api)))

include/linux/mmzone.h

@@ -1981,8 +1981,9 @@ static inline int subsection_map_index(unsigned long pfn)
 static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn)
 {
 	int idx = subsection_map_index(pfn);
+	struct mem_section_usage *usage = READ_ONCE(ms->usage);
 
-	return test_bit(idx, READ_ONCE(ms->usage)->subsection_map);
+	return usage ? test_bit(idx, usage->subsection_map) : 0;
 }
 #else
 static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn)

include/linux/page_ref.h

@@ -230,7 +230,13 @@ static inline int folio_ref_dec_return(struct folio *folio)
 
 static inline bool page_ref_add_unless(struct page *page, int nr, int u)
 {
-	bool ret = atomic_add_unless(&page->_refcount, nr, u);
+	bool ret = false;
+
+	rcu_read_lock();
+	/* avoid writing to the vmemmap area being remapped */
+	if (!page_is_fake_head(page) && page_ref_count(page) != u)
+		ret = atomic_add_unless(&page->_refcount, nr, u);
+	rcu_read_unlock();
 
 	if (page_ref_tracepoint_active(page_ref_mod_unless))
 		__page_ref_mod_unless(page, nr, ret);
@@ -258,54 +264,9 @@ static inline bool folio_try_get(struct folio *folio)
 	return folio_ref_add_unless(folio, 1, 0);
 }
 
-static inline bool folio_ref_try_add_rcu(struct folio *folio, int count)
+static inline bool folio_ref_try_add(struct folio *folio, int count)
 {
-#ifdef CONFIG_TINY_RCU
+	return folio_ref_add_unless(folio, count, 0);
-	/*
-	 * The caller guarantees the folio will not be freed from interrupt
-	 * context, so (on !SMP) we only need preemption to be disabled
-	 * and TINY_RCU does that for us.
-	 */
-# ifdef CONFIG_PREEMPT_COUNT
-	VM_BUG_ON(!in_atomic() && !irqs_disabled());
-# endif
-	VM_BUG_ON_FOLIO(folio_ref_count(folio) == 0, folio);
-	folio_ref_add(folio, count);
-#else
-	if (unlikely(!folio_ref_add_unless(folio, count, 0))) {
-		/* Either the folio has been freed, or will be freed. */
-		return false;
-	}
-#endif
-	return true;
-}
-
-/**
- * folio_try_get_rcu - Attempt to increase the refcount on a folio.
- * @folio: The folio.
- *
- * This is a version of folio_try_get() optimised for non-SMP kernels.
- * If you are still holding the rcu_read_lock() after looking up the
- * page and know that the page cannot have its refcount decreased to
- * zero in interrupt context, you can use this instead of folio_try_get().
- *
- * Example users include get_user_pages_fast() (as pages are not unmapped
- * from interrupt context) and the page cache lookups (as pages are not
- * truncated from interrupt context).  We also know that pages are not
- * frozen in interrupt context for the purposes of splitting or migration.
- *
- * You can also use this function if you're holding a lock that prevents
- * pages being frozen & removed; eg the i_pages lock for the page cache
- * or the mmap_lock or page table lock for page tables.  In this case,
- * it will always succeed, and you could have used a plain folio_get(),
- * but it's sometimes more convenient to have a common function called
- * from both locked and RCU-protected contexts.
- *
- * Return: True if the reference count was successfully incremented.
- */
-static inline bool folio_try_get_rcu(struct folio *folio)
-{
-	return folio_ref_try_add_rcu(folio, 1);
 }
 
 static inline int page_ref_freeze(struct page *page, int count)

include/linux/pagemap.h

@@ -354,11 +354,18 @@ static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
  * a good order (that's 1MB if you're using 4kB pages)
  */
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
-#define MAX_PAGECACHE_ORDER	HPAGE_PMD_ORDER
+#define PREFERRED_MAX_PAGECACHE_ORDER	HPAGE_PMD_ORDER
 #else
-#define MAX_PAGECACHE_ORDER	8
+#define PREFERRED_MAX_PAGECACHE_ORDER	8
 #endif
 
+/*
+ * xas_split_alloc() does not support arbitrary orders. This implies no
+ * 512MB THP on ARM64 with 64KB base page size.
+ */
+#define MAX_XAS_ORDER		(XA_CHUNK_SHIFT * 2 - 1)
+#define MAX_PAGECACHE_ORDER	min(MAX_XAS_ORDER, PREFERRED_MAX_PAGECACHE_ORDER)
+
 /**
  * mapping_set_large_folios() - Indicate the file supports large folios.
  * @mapping: The file.

include/linux/swap.h

@@ -354,7 +354,8 @@ static inline swp_entry_t page_swap_entry(struct page *page)
 }
 
 /* linux/mm/workingset.c */
-bool workingset_test_recent(void *shadow, bool file, bool *workingset);
+bool workingset_test_recent(void *shadow, bool file, bool *workingset,
+				bool flush);
 void workingset_age_nonresident(struct lruvec *lruvec, unsigned long nr_pages);
 void *workingset_eviction(struct folio *folio, struct mem_cgroup *target_memcg);
 void workingset_refault(struct folio *folio, void *shadow);

lib/build_OID_registry

@@ -38,7 +38,9 @@ close IN_FILE || die;
 #
 open C_FILE, ">$ARGV[1]" or die;
 print C_FILE "/*\n";
-print C_FILE " * Automatically generated by ", $0 =~ s#^\Q$abs_srctree/\E##r, ".  Do not edit\n";
+my $scriptname = $0;
+$scriptname =~ s#^\Q$abs_srctree/\E##;
+print C_FILE " * Automatically generated by ", $scriptname, ".  Do not edit\n";
 print C_FILE " */\n";
 
 #

mm/damon/core.c

@@ -1694,14 +1694,31 @@ static void damon_merge_regions_of(struct damon_target *t, unsigned int thres,
  * access frequencies are similar.  This is for minimizing the monitoring
  * overhead under the dynamically changeable access pattern.  If a merge was
  * unnecessarily made, later 'kdamond_split_regions()' will revert it.
+ *
+ * The total number of regions could be higher than the user-defined limit,
+ * max_nr_regions for some cases.  For example, the user can update
+ * max_nr_regions to a number that lower than the current number of regions
+ * while DAMON is running.  For such a case, repeat merging until the limit is
+ * met while increasing @threshold up to possible maximum level.
  */
 static void kdamond_merge_regions(struct damon_ctx *c, unsigned int threshold,
 				  unsigned long sz_limit)
 {
 	struct damon_target *t;
+	unsigned int nr_regions;
+	unsigned int max_thres;
 
-	damon_for_each_target(t, c)
+	max_thres = c->attrs.aggr_interval /
-		damon_merge_regions_of(t, threshold, sz_limit);
+		(c->attrs.sample_interval ?  c->attrs.sample_interval : 1);
+	do {
+		nr_regions = 0;
+		damon_for_each_target(t, c) {
+			damon_merge_regions_of(t, threshold, sz_limit);
+			nr_regions += damon_nr_regions(t);
+		}
+		threshold = max(1, threshold * 2);
+	} while (nr_regions > c->attrs.max_nr_regions &&
+			threshold / 2 < max_thres);
 }
 
 /*

mm/filemap.c

@@ -1847,7 +1847,7 @@ repeat:
 	if (!folio || xa_is_value(folio))
 		goto out;
 
-	if (!folio_try_get_rcu(folio))
+	if (!folio_try_get(folio))
 		goto repeat;
 
 	if (unlikely(folio != xas_reload(&xas))) {
@@ -2001,7 +2001,7 @@ retry:
 	if (!folio || xa_is_value(folio))
 		return folio;
 
-	if (!folio_try_get_rcu(folio))
+	if (!folio_try_get(folio))
 		goto reset;
 
 	if (unlikely(folio != xas_reload(xas))) {
@@ -2181,7 +2181,7 @@ unsigned filemap_get_folios_contig(struct address_space *mapping,
 		if (xa_is_value(folio))
 			goto update_start;
 
-		if (!folio_try_get_rcu(folio))
+		if (!folio_try_get(folio))
 			goto retry;
 
 		if (unlikely(folio != xas_reload(&xas)))
@@ -2313,7 +2313,7 @@ static void filemap_get_read_batch(struct address_space *mapping,
 			break;
 		if (xa_is_sibling(folio))
 			break;
-		if (!folio_try_get_rcu(folio))
+		if (!folio_try_get(folio))
 			goto retry;
 
 		if (unlikely(folio != xas_reload(&xas)))
@@ -3124,7 +3124,7 @@ static struct file *do_sync_mmap_readahead(struct vm_fault *vmf)
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 	/* Use the readahead code, even if readahead is disabled */
-	if (vm_flags & VM_HUGEPAGE) {
+	if ((vm_flags & VM_HUGEPAGE) && HPAGE_PMD_ORDER <= MAX_PAGECACHE_ORDER) {
 		fpin = maybe_unlock_mmap_for_io(vmf, fpin);
 		ractl._index &= ~((unsigned long)HPAGE_PMD_NR - 1);
 		ra->size = HPAGE_PMD_NR;
@@ -3472,7 +3472,7 @@ static struct folio *next_uptodate_folio(struct xa_state *xas,
 			continue;
 		if (folio_test_locked(folio))
 			continue;
-		if (!folio_try_get_rcu(folio))
+		if (!folio_try_get(folio))
 			continue;
 		/* Has the page moved or been split? */
 		if (unlikely(folio != xas_reload(xas)))
@@ -4248,6 +4248,9 @@ static void filemap_cachestat(struct address_space *mapping,
 	XA_STATE(xas, &mapping->i_pages, first_index);
 	struct folio *folio;
 
+	/* Flush stats (and potentially sleep) outside the RCU read section. */
+	mem_cgroup_flush_stats_ratelimited(NULL);
+
 	rcu_read_lock();
 	xas_for_each(&xas, folio, last_index) {
 		int order;
@@ -4311,7 +4314,7 @@ static void filemap_cachestat(struct address_space *mapping,
 					goto resched;
 			}
 #endif
-			if (workingset_test_recent(shadow, true, &workingset))
+			if (workingset_test_recent(shadow, true, &workingset, false))
 				cs->nr_recently_evicted += nr_pages;
 
 			goto resched;

mm/gup.c

@@ -76,7 +76,7 @@ retry:
 	folio = page_folio(page);
 	if (WARN_ON_ONCE(folio_ref_count(folio) < 0))
 		return NULL;
-	if (unlikely(!folio_ref_try_add_rcu(folio, refs)))
+	if (unlikely(!folio_ref_try_add(folio, refs)))
 		return NULL;
 
 	/*
@@ -97,95 +97,6 @@ retry:
 	return folio;
 }
 
-/**
- * try_grab_folio() - Attempt to get or pin a folio.
- * @page:  pointer to page to be grabbed
- * @refs:  the value to (effectively) add to the folio's refcount
- * @flags: gup flags: these are the FOLL_* flag values.
- *
- * "grab" names in this file mean, "look at flags to decide whether to use
- * FOLL_PIN or FOLL_GET behavior, when incrementing the folio's refcount.
- *
- * Either FOLL_PIN or FOLL_GET (or neither) must be set, but not both at the
- * same time. (That's true throughout the get_user_pages*() and
- * pin_user_pages*() APIs.) Cases:
- *
- *    FOLL_GET: folio's refcount will be incremented by @refs.
- *
- *    FOLL_PIN on large folios: folio's refcount will be incremented by
- *    @refs, and its pincount will be incremented by @refs.
- *
- *    FOLL_PIN on single-page folios: folio's refcount will be incremented by
- *    @refs * GUP_PIN_COUNTING_BIAS.
- *
- * Return: The folio containing @page (with refcount appropriately
- * incremented) for success, or NULL upon failure. If neither FOLL_GET
- * nor FOLL_PIN was set, that's considered failure, and furthermore,
- * a likely bug in the caller, so a warning is also emitted.
- */
-struct folio *try_grab_folio(struct page *page, int refs, unsigned int flags)
-{
-	struct folio *folio;
-
-	if (WARN_ON_ONCE((flags & (FOLL_GET | FOLL_PIN)) == 0))
-		return NULL;
-
-	if (unlikely(!(flags & FOLL_PCI_P2PDMA) && is_pci_p2pdma_page(page)))
-		return NULL;
-
-	if (flags & FOLL_GET)
-		return try_get_folio(page, refs);
-
-	/* FOLL_PIN is set */
-
-	/*
-	 * Don't take a pin on the zero page - it's not going anywhere
-	 * and it is used in a *lot* of places.
-	 */
-	if (is_zero_page(page))
-		return page_folio(page);
-
-	folio = try_get_folio(page, refs);
-	if (!folio)
-		return NULL;
-
-	/*
-	 * Can't do FOLL_LONGTERM + FOLL_PIN gup fast path if not in a
-	 * right zone, so fail and let the caller fall back to the slow
-	 * path.
-	 */
-	if (unlikely((flags & FOLL_LONGTERM) &&
-		     !folio_is_longterm_pinnable(folio))) {
-		if (!put_devmap_managed_folio_refs(folio, refs))
-			folio_put_refs(folio, refs);
-		return NULL;
-	}
-
-	/*
-	 * When pinning a large folio, use an exact count to track it.
-	 *
-	 * However, be sure to *also* increment the normal folio
-	 * refcount field at least once, so that the folio really
-	 * is pinned.  That's why the refcount from the earlier
-	 * try_get_folio() is left intact.
-	 */
-	if (folio_test_large(folio))
-		atomic_add(refs, &folio->_pincount);
-	else
-		folio_ref_add(folio,
-				refs * (GUP_PIN_COUNTING_BIAS - 1));
-	/*
-	 * Adjust the pincount before re-checking the PTE for changes.
-	 * This is essentially a smp_mb() and is paired with a memory
-	 * barrier in folio_try_share_anon_rmap_*().
-	 */
-	smp_mb__after_atomic();
-
-	node_stat_mod_folio(folio, NR_FOLL_PIN_ACQUIRED, refs);
-
-	return folio;
-}
-
 static void gup_put_folio(struct folio *folio, int refs, unsigned int flags)
 {
 	if (flags & FOLL_PIN) {
@@ -203,58 +114,59 @@ static void gup_put_folio(struct folio *folio, int refs, unsigned int flags)
 }
 
 /**
- * try_grab_page() - elevate a page's refcount by a flag-dependent amount
+ * try_grab_folio() - add a folio's refcount by a flag-dependent amount
- * @page:    pointer to page to be grabbed
+ * @folio:    pointer to folio to be grabbed
- * @flags:   gup flags: these are the FOLL_* flag values.
+ * @refs:     the value to (effectively) add to the folio's refcount
+ * @flags:    gup flags: these are the FOLL_* flag values
  *
  * This might not do anything at all, depending on the flags argument.
  *
  * "grab" names in this file mean, "look at flags to decide whether to use
- * FOLL_PIN or FOLL_GET behavior, when incrementing the page's refcount.
+ * FOLL_PIN or FOLL_GET behavior, when incrementing the folio's refcount.
  *
  * Either FOLL_PIN or FOLL_GET (or neither) may be set, but not both at the same
- * time. Cases: please see the try_grab_folio() documentation, with
+ * time.
- * "refs=1".
  *
  * Return: 0 for success, or if no action was required (if neither FOLL_PIN
  * nor FOLL_GET was set, nothing is done). A negative error code for failure:
  *
- *   -ENOMEM		FOLL_GET or FOLL_PIN was set, but the page could not
+ *   -ENOMEM		FOLL_GET or FOLL_PIN was set, but the folio could not
  *			be grabbed.
+ *
+ * It is called when we have a stable reference for the folio, typically in
+ * GUP slow path.
  */
-int __must_check try_grab_page(struct page *page, unsigned int flags)
+int __must_check try_grab_folio(struct folio *folio, int refs,
+				unsigned int flags)
 {
-	struct folio *folio = page_folio(page);
-
 	if (WARN_ON_ONCE(folio_ref_count(folio) <= 0))
 		return -ENOMEM;
 
-	if (unlikely(!(flags & FOLL_PCI_P2PDMA) && is_pci_p2pdma_page(page)))
+	if (unlikely(!(flags & FOLL_PCI_P2PDMA) && is_pci_p2pdma_page(&folio->page)))
 		return -EREMOTEIO;
 
 	if (flags & FOLL_GET)
-		folio_ref_inc(folio);
+		folio_ref_add(folio, refs);
 	else if (flags & FOLL_PIN) {
 		/*
 		 * Don't take a pin on the zero page - it's not going anywhere
 		 * and it is used in a *lot* of places.
 		 */
-		if (is_zero_page(page))
+		if (is_zero_folio(folio))
 			return 0;
 
 		/*
-		 * Similar to try_grab_folio(): be sure to *also*
+		 * Increment the normal page refcount field at least once,
-		 * increment the normal page refcount field at least once,
 		 * so that the page really is pinned.
 		 */
 		if (folio_test_large(folio)) {
-			folio_ref_add(folio, 1);
+			folio_ref_add(folio, refs);
-			atomic_add(1, &folio->_pincount);
+			atomic_add(refs, &folio->_pincount);
 		} else {
-			folio_ref_add(folio, GUP_PIN_COUNTING_BIAS);
+			folio_ref_add(folio, refs * GUP_PIN_COUNTING_BIAS);
 		}
 
-		node_stat_mod_folio(folio, NR_FOLL_PIN_ACQUIRED, 1);
+		node_stat_mod_folio(folio, NR_FOLL_PIN_ACQUIRED, refs);
 	}
 
 	return 0;
@@ -515,6 +427,102 @@ static int record_subpages(struct page *page, unsigned long sz,
 
 	return nr;
 }
+
+/**
+ * try_grab_folio_fast() - Attempt to get or pin a folio in fast path.
+ * @page:  pointer to page to be grabbed
+ * @refs:  the value to (effectively) add to the folio's refcount
+ * @flags: gup flags: these are the FOLL_* flag values.
+ *
+ * "grab" names in this file mean, "look at flags to decide whether to use
+ * FOLL_PIN or FOLL_GET behavior, when incrementing the folio's refcount.
+ *
+ * Either FOLL_PIN or FOLL_GET (or neither) must be set, but not both at the
+ * same time. (That's true throughout the get_user_pages*() and
+ * pin_user_pages*() APIs.) Cases:
+ *
+ *    FOLL_GET: folio's refcount will be incremented by @refs.
+ *
+ *    FOLL_PIN on large folios: folio's refcount will be incremented by
+ *    @refs, and its pincount will be incremented by @refs.
+ *
+ *    FOLL_PIN on single-page folios: folio's refcount will be incremented by
+ *    @refs * GUP_PIN_COUNTING_BIAS.
+ *
+ * Return: The folio containing @page (with refcount appropriately
+ * incremented) for success, or NULL upon failure. If neither FOLL_GET
+ * nor FOLL_PIN was set, that's considered failure, and furthermore,
+ * a likely bug in the caller, so a warning is also emitted.
+ *
+ * It uses add ref unless zero to elevate the folio refcount and must be called
+ * in fast path only.
+ */
+static struct folio *try_grab_folio_fast(struct page *page, int refs,
+					 unsigned int flags)
+{
+	struct folio *folio;
+
+	/* Raise warn if it is not called in fast GUP */
+	VM_WARN_ON_ONCE(!irqs_disabled());
+
+	if (WARN_ON_ONCE((flags & (FOLL_GET | FOLL_PIN)) == 0))
+		return NULL;
+
+	if (unlikely(!(flags & FOLL_PCI_P2PDMA) && is_pci_p2pdma_page(page)))
+		return NULL;
+
+	if (flags & FOLL_GET)
+		return try_get_folio(page, refs);
+
+	/* FOLL_PIN is set */
+
+	/*
+	 * Don't take a pin on the zero page - it's not going anywhere
+	 * and it is used in a *lot* of places.
+	 */
+	if (is_zero_page(page))
+		return page_folio(page);
+
+	folio = try_get_folio(page, refs);
+	if (!folio)
+		return NULL;
+
+	/*
+	 * Can't do FOLL_LONGTERM + FOLL_PIN gup fast path if not in a
+	 * right zone, so fail and let the caller fall back to the slow
+	 * path.
+	 */
+	if (unlikely((flags & FOLL_LONGTERM) &&
+		     !folio_is_longterm_pinnable(folio))) {
+		if (!put_devmap_managed_folio_refs(folio, refs))
+			folio_put_refs(folio, refs);
+		return NULL;
+	}
+
+	/*
+	 * When pinning a large folio, use an exact count to track it.
+	 *
+	 * However, be sure to *also* increment the normal folio
+	 * refcount field at least once, so that the folio really
+	 * is pinned.  That's why the refcount from the earlier
+	 * try_get_folio() is left intact.
+	 */
+	if (folio_test_large(folio))
+		atomic_add(refs, &folio->_pincount);
+	else
+		folio_ref_add(folio,
+				refs * (GUP_PIN_COUNTING_BIAS - 1));
+	/*
+	 * Adjust the pincount before re-checking the PTE for changes.
+	 * This is essentially a smp_mb() and is paired with a memory
+	 * barrier in folio_try_share_anon_rmap_*().
+	 */
+	smp_mb__after_atomic();
+
+	node_stat_mod_folio(folio, NR_FOLL_PIN_ACQUIRED, refs);
+
+	return folio;
+}
 #endif	/* CONFIG_ARCH_HAS_HUGEPD || CONFIG_HAVE_GUP_FAST */
 
 #ifdef CONFIG_ARCH_HAS_HUGEPD
@@ -535,7 +543,7 @@ static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end,
  */
 static int gup_hugepte(struct vm_area_struct *vma, pte_t *ptep, unsigned long sz,
 		       unsigned long addr, unsigned long end, unsigned int flags,
-		       struct page **pages, int *nr)
+		       struct page **pages, int *nr, bool fast)
 {
 	unsigned long pte_end;
 	struct page *page;
@@ -558,9 +566,15 @@ static int gup_hugepte(struct vm_area_struct *vma, pte_t *ptep, unsigned long sz
 	page = pte_page(pte);
 	refs = record_subpages(page, sz, addr, end, pages + *nr);
 
-	folio = try_grab_folio(page, refs, flags);
+	if (fast) {
-	if (!folio)
+		folio = try_grab_folio_fast(page, refs, flags);
-		return 0;
+		if (!folio)
+			return 0;
+	} else {
+		folio = page_folio(page);
+		if (try_grab_folio(folio, refs, flags))
+			return 0;
+	}
 
 	if (unlikely(pte_val(pte) != pte_val(ptep_get(ptep)))) {
 		gup_put_folio(folio, refs, flags);
@@ -588,7 +602,7 @@ static int gup_hugepte(struct vm_area_struct *vma, pte_t *ptep, unsigned long sz
 static int gup_hugepd(struct vm_area_struct *vma, hugepd_t hugepd,
 		      unsigned long addr, unsigned int pdshift,
 		      unsigned long end, unsigned int flags,
-		      struct page **pages, int *nr)
+		      struct page **pages, int *nr, bool fast)
 {
 	pte_t *ptep;
 	unsigned long sz = 1UL << hugepd_shift(hugepd);
@@ -598,7 +612,8 @@ static int gup_hugepd(struct vm_area_struct *vma, hugepd_t hugepd,
 	ptep = hugepte_offset(hugepd, addr, pdshift);
 	do {
 		next = hugepte_addr_end(addr, end, sz);
-		ret = gup_hugepte(vma, ptep, sz, addr, end, flags, pages, nr);
+		ret = gup_hugepte(vma, ptep, sz, addr, end, flags, pages, nr,
+				  fast);
 		if (ret != 1)
 			return ret;
 	} while (ptep++, addr = next, addr != end);
@@ -625,7 +640,7 @@ static struct page *follow_hugepd(struct vm_area_struct *vma, hugepd_t hugepd,
 	ptep = hugepte_offset(hugepd, addr, pdshift);
 	ptl = huge_pte_lock(h, vma->vm_mm, ptep);
 	ret = gup_hugepd(vma, hugepd, addr, pdshift, addr + PAGE_SIZE,
-			 flags, &page, &nr);
+			 flags, &page, &nr, false);
 	spin_unlock(ptl);
 
 	if (ret == 1) {
@@ -642,7 +657,7 @@ static struct page *follow_hugepd(struct vm_area_struct *vma, hugepd_t hugepd,
 static inline int gup_hugepd(struct vm_area_struct *vma, hugepd_t hugepd,
 			     unsigned long addr, unsigned int pdshift,
 			     unsigned long end, unsigned int flags,
-			     struct page **pages, int *nr)
+			     struct page **pages, int *nr, bool fast)
 {
 	return 0;
 }
@@ -729,7 +744,7 @@ static struct page *follow_huge_pud(struct vm_area_struct *vma,
 	    gup_must_unshare(vma, flags, page))
 		return ERR_PTR(-EMLINK);
 
-	ret = try_grab_page(page, flags);
+	ret = try_grab_folio(page_folio(page), 1, flags);
 	if (ret)
 		page = ERR_PTR(ret);
 	else
@@ -806,7 +821,7 @@ static struct page *follow_huge_pmd(struct vm_area_struct *vma,
 	VM_BUG_ON_PAGE((flags & FOLL_PIN) && PageAnon(page) &&
 			!PageAnonExclusive(page), page);
 
-	ret = try_grab_page(page, flags);
+	ret = try_grab_folio(page_folio(page), 1, flags);
 	if (ret)
 		return ERR_PTR(ret);
 
@@ -968,8 +983,8 @@ static struct page *follow_page_pte(struct vm_area_struct *vma,
 	VM_BUG_ON_PAGE((flags & FOLL_PIN) && PageAnon(page) &&
 		       !PageAnonExclusive(page), page);
 
-	/* try_grab_page() does nothing unless FOLL_GET or FOLL_PIN is set. */
+	/* try_grab_folio() does nothing unless FOLL_GET or FOLL_PIN is set. */
-	ret = try_grab_page(page, flags);
+	ret = try_grab_folio(page_folio(page), 1, flags);
 	if (unlikely(ret)) {
 		page = ERR_PTR(ret);
 		goto out;
@@ -1233,7 +1248,7 @@ static int get_gate_page(struct mm_struct *mm, unsigned long address,
 			goto unmap;
 		*page = pte_page(entry);
 	}
-	ret = try_grab_page(*page, gup_flags);
+	ret = try_grab_folio(page_folio(*page), 1, gup_flags);
 	if (unlikely(ret))
 		goto unmap;
 out:
@@ -1636,20 +1651,19 @@ next_page:
 			 * pages.
 			 */
 			if (page_increm > 1) {
-				struct folio *folio;
+				struct folio *folio = page_folio(page);
 
 				/*
 				 * Since we already hold refcount on the
 				 * large folio, this should never fail.
 				 */
-				folio = try_grab_folio(page, page_increm - 1,
+				if (try_grab_folio(folio, page_increm - 1,
-						       foll_flags);
+						   foll_flags)) {
-				if (WARN_ON_ONCE(!folio)) {
 					/*
 					 * Release the 1st page ref if the
 					 * folio is problematic, fail hard.
 					 */
-					gup_put_folio(page_folio(page), 1,
+					gup_put_folio(folio, 1,
 						      foll_flags);
 					ret = -EFAULT;
 					goto out;
@@ -2797,7 +2811,6 @@ EXPORT_SYMBOL(get_user_pages_unlocked);
  * This code is based heavily on the PowerPC implementation by Nick Piggin.
  */
 #ifdef CONFIG_HAVE_GUP_FAST
-
 /*
  * Used in the GUP-fast path to determine whether GUP is permitted to work on
  * a specific folio.
@@ -2962,7 +2975,7 @@ static int gup_fast_pte_range(pmd_t pmd, pmd_t *pmdp, unsigned long addr,
 		VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
 		page = pte_page(pte);
 
-		folio = try_grab_folio(page, 1, flags);
+		folio = try_grab_folio_fast(page, 1, flags);
 		if (!folio)
 			goto pte_unmap;
 
@@ -3049,7 +3062,7 @@ static int gup_fast_devmap_leaf(unsigned long pfn, unsigned long addr,
 			break;
 		}
 
-		folio = try_grab_folio(page, 1, flags);
+		folio = try_grab_folio_fast(page, 1, flags);
 		if (!folio) {
 			gup_fast_undo_dev_pagemap(nr, nr_start, flags, pages);
 			break;
@@ -3138,7 +3151,7 @@ static int gup_fast_pmd_leaf(pmd_t orig, pmd_t *pmdp, unsigned long addr,
 	page = pmd_page(orig);
 	refs = record_subpages(page, PMD_SIZE, addr, end, pages + *nr);
 
-	folio = try_grab_folio(page, refs, flags);
+	folio = try_grab_folio_fast(page, refs, flags);
 	if (!folio)
 		return 0;
 
@@ -3182,7 +3195,7 @@ static int gup_fast_pud_leaf(pud_t orig, pud_t *pudp, unsigned long addr,
 	page = pud_page(orig);
 	refs = record_subpages(page, PUD_SIZE, addr, end, pages + *nr);
 
-	folio = try_grab_folio(page, refs, flags);
+	folio = try_grab_folio_fast(page, refs, flags);
 	if (!folio)
 		return 0;
 
@@ -3222,7 +3235,7 @@ static int gup_fast_pgd_leaf(pgd_t orig, pgd_t *pgdp, unsigned long addr,
 	page = pgd_page(orig);
 	refs = record_subpages(page, PGDIR_SIZE, addr, end, pages + *nr);
 
-	folio = try_grab_folio(page, refs, flags);
+	folio = try_grab_folio_fast(page, refs, flags);
 	if (!folio)
 		return 0;
 
@@ -3276,7 +3289,8 @@ static int gup_fast_pmd_range(pud_t *pudp, pud_t pud, unsigned long addr,
 			 * pmd format and THP pmd format
 			 */
 			if (gup_hugepd(NULL, __hugepd(pmd_val(pmd)), addr,
-				       PMD_SHIFT, next, flags, pages, nr) != 1)
+				       PMD_SHIFT, next, flags, pages, nr,
+				       true) != 1)
 				return 0;
 		} else if (!gup_fast_pte_range(pmd, pmdp, addr, next, flags,
 					       pages, nr))
@@ -3306,7 +3320,8 @@ static int gup_fast_pud_range(p4d_t *p4dp, p4d_t p4d, unsigned long addr,
 				return 0;
 		} else if (unlikely(is_hugepd(__hugepd(pud_val(pud))))) {
 			if (gup_hugepd(NULL, __hugepd(pud_val(pud)), addr,
-				       PUD_SHIFT, next, flags, pages, nr) != 1)
+				       PUD_SHIFT, next, flags, pages, nr,
+				       true) != 1)
 				return 0;
 		} else if (!gup_fast_pmd_range(pudp, pud, addr, next, flags,
 					       pages, nr))
@@ -3333,7 +3348,8 @@ static int gup_fast_p4d_range(pgd_t *pgdp, pgd_t pgd, unsigned long addr,
 		BUILD_BUG_ON(p4d_leaf(p4d));
 		if (unlikely(is_hugepd(__hugepd(p4d_val(p4d))))) {
 			if (gup_hugepd(NULL, __hugepd(p4d_val(p4d)), addr,
-				       P4D_SHIFT, next, flags, pages, nr) != 1)
+				       P4D_SHIFT, next, flags, pages, nr,
+				       true) != 1)
 				return 0;
 		} else if (!gup_fast_pud_range(p4dp, p4d, addr, next, flags,
 					       pages, nr))
@@ -3362,7 +3378,8 @@ static void gup_fast_pgd_range(unsigned long addr, unsigned long end,
 				return;
 		} else if (unlikely(is_hugepd(__hugepd(pgd_val(pgd))))) {
 			if (gup_hugepd(NULL, __hugepd(pgd_val(pgd)), addr,
-				       PGDIR_SHIFT, next, flags, pages, nr) != 1)
+				       PGDIR_SHIFT, next, flags, pages, nr,
+				       true) != 1)
 				return;
 		} else if (!gup_fast_p4d_range(pgdp, pgd, addr, next, flags,
 					       pages, nr))

mm/huge_memory.c

@@ -1333,7 +1333,7 @@ struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
 	if (!*pgmap)
 		return ERR_PTR(-EFAULT);
 	page = pfn_to_page(pfn);
-	ret = try_grab_page(page, flags);
+	ret = try_grab_folio(page_folio(page), 1, flags);
 	if (ret)
 		page = ERR_PTR(ret);
 

mm/hugetlb.c

@@ -1629,13 +1629,10 @@ static inline void destroy_compound_gigantic_folio(struct folio *folio,
  * folio appears as just a compound page.  Otherwise, wait until after
  * allocating vmemmap to clear the flag.
  *
- * A reference is held on the folio, except in the case of demote.
- *
  * Must be called with hugetlb lock held.
  */
-static void __remove_hugetlb_folio(struct hstate *h, struct folio *folio,
+static void remove_hugetlb_folio(struct hstate *h, struct folio *folio,
-							bool adjust_surplus,
+							bool adjust_surplus)
-							bool demote)
 {
 	int nid = folio_nid(folio);
 
@@ -1649,6 +1646,7 @@ static void __remove_hugetlb_folio(struct hstate *h, struct folio *folio,
 	list_del(&folio->lru);
 
 	if (folio_test_hugetlb_freed(folio)) {
+		folio_clear_hugetlb_freed(folio);
 		h->free_huge_pages--;
 		h->free_huge_pages_node[nid]--;
 	}
@@ -1665,33 +1663,13 @@ static void __remove_hugetlb_folio(struct hstate *h, struct folio *folio,
 	if (!folio_test_hugetlb_vmemmap_optimized(folio))
 		__folio_clear_hugetlb(folio);
 
-	 /*
-	  * In the case of demote we do not ref count the page as it will soon
-	  * be turned into a page of smaller size.
-	 */
-	if (!demote)
-		folio_ref_unfreeze(folio, 1);
-
 	h->nr_huge_pages--;
 	h->nr_huge_pages_node[nid]--;
 }
 
-static void remove_hugetlb_folio(struct hstate *h, struct folio *folio,
-							bool adjust_surplus)
-{
-	__remove_hugetlb_folio(h, folio, adjust_surplus, false);
-}
-
-static void remove_hugetlb_folio_for_demote(struct hstate *h, struct folio *folio,
-							bool adjust_surplus)
-{
-	__remove_hugetlb_folio(h, folio, adjust_surplus, true);
-}
-
 static void add_hugetlb_folio(struct hstate *h, struct folio *folio,
 			     bool adjust_surplus)
 {
-	int zeroed;
 	int nid = folio_nid(folio);
 
 	VM_BUG_ON_FOLIO(!folio_test_hugetlb_vmemmap_optimized(folio), folio);
@@ -1715,21 +1693,6 @@ static void add_hugetlb_folio(struct hstate *h, struct folio *folio,
 	 */
 	folio_set_hugetlb_vmemmap_optimized(folio);
 
-	/*
-	 * This folio is about to be managed by the hugetlb allocator and
-	 * should have no users.  Drop our reference, and check for others
-	 * just in case.
-	 */
-	zeroed = folio_put_testzero(folio);
-	if (unlikely(!zeroed))
-		/*
-		 * It is VERY unlikely soneone else has taken a ref
-		 * on the folio.  In this case, we simply return as
-		 * free_huge_folio() will be called when this other ref
-		 * is dropped.
-		 */
-		return;
-
 	arch_clear_hugetlb_flags(folio);
 	enqueue_hugetlb_folio(h, folio);
 }
@@ -1783,6 +1746,8 @@ static void __update_and_free_hugetlb_folio(struct hstate *h,
 		spin_unlock_irq(&hugetlb_lock);
 	}
 
+	folio_ref_unfreeze(folio, 1);
+
 	/*
 	 * Non-gigantic pages demoted from CMA allocated gigantic pages
 	 * need to be given back to CMA in free_gigantic_folio.
@@ -3106,11 +3071,8 @@ retry:
 
 free_new:
 	spin_unlock_irq(&hugetlb_lock);
-	if (new_folio) {
+	if (new_folio)
-		/* Folio has a zero ref count, but needs a ref to be freed */
-		folio_ref_unfreeze(new_folio, 1);
 		update_and_free_hugetlb_folio(h, new_folio, false);
-	}
 
 	return ret;
 }
@@ -3965,7 +3927,7 @@ static int demote_free_hugetlb_folio(struct hstate *h, struct folio *folio)
 
 	target_hstate = size_to_hstate(PAGE_SIZE << h->demote_order);
 
-	remove_hugetlb_folio_for_demote(h, folio, false);
+	remove_hugetlb_folio(h, folio, false);
 	spin_unlock_irq(&hugetlb_lock);
 
 	/*
@@ -3979,7 +3941,6 @@ static int demote_free_hugetlb_folio(struct hstate *h, struct folio *folio)
 		if (rc) {
 			/* Allocation of vmemmmap failed, we can not demote folio */
 			spin_lock_irq(&hugetlb_lock);
-			folio_ref_unfreeze(folio, 1);
 			add_hugetlb_folio(h, folio, false);
 			return rc;
 		}

mm/hugetlb_vmemmap.c

@@ -455,6 +455,8 @@ static int __hugetlb_vmemmap_restore_folio(const struct hstate *h,
 	unsigned long vmemmap_reuse;
 
 	VM_WARN_ON_ONCE_FOLIO(!folio_test_hugetlb(folio), folio);
+	VM_WARN_ON_ONCE_FOLIO(folio_ref_count(folio), folio);
+
 	if (!folio_test_hugetlb_vmemmap_optimized(folio))
 		return 0;
 
@@ -490,6 +492,9 @@ static int __hugetlb_vmemmap_restore_folio(const struct hstate *h,
  */
 int hugetlb_vmemmap_restore_folio(const struct hstate *h, struct folio *folio)
 {
+	/* avoid writes from page_ref_add_unless() while unfolding vmemmap */
+	synchronize_rcu();
+
 	return __hugetlb_vmemmap_restore_folio(h, folio, 0);
 }
 
@@ -514,6 +519,9 @@ long hugetlb_vmemmap_restore_folios(const struct hstate *h,
 	long restored = 0;
 	long ret = 0;
 
+	/* avoid writes from page_ref_add_unless() while unfolding vmemmap */
+	synchronize_rcu();
+
 	list_for_each_entry_safe(folio, t_folio, folio_list, lru) {
 		if (folio_test_hugetlb_vmemmap_optimized(folio)) {
 			ret = __hugetlb_vmemmap_restore_folio(h, folio,
@@ -559,6 +567,8 @@ static int __hugetlb_vmemmap_optimize_folio(const struct hstate *h,
 	unsigned long vmemmap_reuse;
 
 	VM_WARN_ON_ONCE_FOLIO(!folio_test_hugetlb(folio), folio);
+	VM_WARN_ON_ONCE_FOLIO(folio_ref_count(folio), folio);
+
 	if (!vmemmap_should_optimize_folio(h, folio))
 		return ret;
 
@@ -610,6 +620,9 @@ void hugetlb_vmemmap_optimize_folio(const struct hstate *h, struct folio *folio)
 {
 	LIST_HEAD(vmemmap_pages);
 
+	/* avoid writes from page_ref_add_unless() while folding vmemmap */
+	synchronize_rcu();
+
 	__hugetlb_vmemmap_optimize_folio(h, folio, &vmemmap_pages, 0);
 	free_vmemmap_page_list(&vmemmap_pages);
 }
@@ -653,6 +666,9 @@ void hugetlb_vmemmap_optimize_folios(struct hstate *h, struct list_head *folio_l
 
 	flush_tlb_all();
 
+	/* avoid writes from page_ref_add_unless() while folding vmemmap */
+	synchronize_rcu();
+
 	list_for_each_entry(folio, folio_list, lru) {
 		int ret;
 

mm/internal.h

@@ -1226,8 +1226,8 @@ int migrate_device_coherent_page(struct page *page);
 /*
  * mm/gup.c
  */
-struct folio *try_grab_folio(struct page *page, int refs, unsigned int flags);
+int __must_check try_grab_folio(struct folio *folio, int refs,
-int __must_check try_grab_page(struct page *page, unsigned int flags);
+				unsigned int flags);
 
 /*
  * mm/huge_memory.c

mm/memcontrol.c

@@ -4948,17 +4948,6 @@ void mem_cgroup_migrate(struct folio *old, struct folio *new)
 
 	/* Transfer the charge and the css ref */
 	commit_charge(new, memcg);
-	/*
-	 * If the old folio is a large folio and is in the split queue, it needs
-	 * to be removed from the split queue now, in case getting an incorrect
-	 * split queue in destroy_large_folio() after the memcg of the old folio
-	 * is cleared.
-	 *
-	 * In addition, the old folio is about to be freed after migration, so
-	 * removing from the split queue a bit earlier seems reasonable.
-	 */
-	if (folio_test_large(old) && folio_test_large_rmappable(old))
-		folio_undo_large_rmappable(old);
 	old->memcg_data = 0;
 }
 

mm/migrate.c

@@ -415,6 +415,15 @@ int folio_migrate_mapping(struct address_space *mapping,
 		if (folio_ref_count(folio) != expected_count)
 			return -EAGAIN;
 
+		/* Take off deferred split queue while frozen and memcg set */
+		if (folio_test_large(folio) &&
+		    folio_test_large_rmappable(folio)) {
+			if (!folio_ref_freeze(folio, expected_count))
+				return -EAGAIN;
+			folio_undo_large_rmappable(folio);
+			folio_ref_unfreeze(folio, expected_count);
+		}
+
 		/* No turning back from here */
 		newfolio->index = folio->index;
 		newfolio->mapping = folio->mapping;
@@ -433,6 +442,10 @@ int folio_migrate_mapping(struct address_space *mapping,
 		return -EAGAIN;
 	}
 
+	/* Take off deferred split queue while frozen and memcg set */
+	if (folio_test_large(folio) && folio_test_large_rmappable(folio))
+		folio_undo_large_rmappable(folio);
+
 	/*
 	 * Now we know that no one else is looking at the folio:
 	 * no turning back from here.

mm/readahead.c

@@ -449,11 +449,11 @@ void page_cache_ra_order(struct readahead_control *ractl,
 
 	limit = min(limit, index + ra->size - 1);
 
-	if (new_order < MAX_PAGECACHE_ORDER) {
+	if (new_order < MAX_PAGECACHE_ORDER)
 		new_order += 2;
-		new_order = min_t(unsigned int, MAX_PAGECACHE_ORDER, new_order);
+
-		new_order = min_t(unsigned int, new_order, ilog2(ra->size));
+	new_order = min_t(unsigned int, MAX_PAGECACHE_ORDER, new_order);
-	}
+	new_order = min_t(unsigned int, new_order, ilog2(ra->size));
 
 	/* See comment in page_cache_ra_unbounded() */
 	nofs = memalloc_nofs_save();

mm/shmem.c

@@ -548,8 +548,9 @@ static bool shmem_confirm_swap(struct address_space *mapping,
 
 static int shmem_huge __read_mostly = SHMEM_HUGE_NEVER;
 
-bool shmem_is_huge(struct inode *inode, pgoff_t index, bool shmem_huge_force,
+static bool __shmem_is_huge(struct inode *inode, pgoff_t index,
-		   struct mm_struct *mm, unsigned long vm_flags)
+			    bool shmem_huge_force, struct mm_struct *mm,
+			    unsigned long vm_flags)
 {
 	loff_t i_size;
 
@@ -580,6 +581,16 @@ bool shmem_is_huge(struct inode *inode, pgoff_t index, bool shmem_huge_force,
 	}
 }
 
+bool shmem_is_huge(struct inode *inode, pgoff_t index,
+		   bool shmem_huge_force, struct mm_struct *mm,
+		   unsigned long vm_flags)
+{
+	if (HPAGE_PMD_ORDER > MAX_PAGECACHE_ORDER)
+		return false;
+
+	return __shmem_is_huge(inode, index, shmem_huge_force, mm, vm_flags);
+}
+
 #if defined(CONFIG_SYSFS)
 static int shmem_parse_huge(const char *str)
 {

mm/vmalloc.c

@@ -2544,7 +2544,15 @@ static DEFINE_PER_CPU(struct vmap_block_queue, vmap_block_queue);
 static struct xarray *
 addr_to_vb_xa(unsigned long addr)
 {
-	int index = (addr / VMAP_BLOCK_SIZE) % num_possible_cpus();
+	int index = (addr / VMAP_BLOCK_SIZE) % nr_cpu_ids;
+
+	/*
+	 * Please note, nr_cpu_ids points on a highest set
+	 * possible bit, i.e. we never invoke cpumask_next()
+	 * if an index points on it which is nr_cpu_ids - 1.
+	 */
+	if (!cpu_possible(index))
+		index = cpumask_next(index, cpu_possible_mask);
 
 	return &per_cpu(vmap_block_queue, index).vmap_blocks;
 }

mm/workingset.c

@@ -412,10 +412,12 @@ void *workingset_eviction(struct folio *folio, struct mem_cgroup *target_memcg)
  * @file: whether the corresponding folio is from the file lru.
  * @workingset: where the workingset value unpacked from shadow should
  * be stored.
+ * @flush: whether to flush cgroup rstat.
  *
  * Return: true if the shadow is for a recently evicted folio; false otherwise.
  */
-bool workingset_test_recent(void *shadow, bool file, bool *workingset)
+bool workingset_test_recent(void *shadow, bool file, bool *workingset,
+				bool flush)
 {
 	struct mem_cgroup *eviction_memcg;
 	struct lruvec *eviction_lruvec;
@@ -467,10 +469,16 @@ bool workingset_test_recent(void *shadow, bool file, bool *workingset)
 
 	/*
 	 * Flush stats (and potentially sleep) outside the RCU read section.
+	 *
+	 * Note that workingset_test_recent() itself might be called in RCU read
+	 * section (for e.g, in cachestat) - these callers need to skip flushing
+	 * stats (via the flush argument).
+	 *
 	 * XXX: With per-memcg flushing and thresholding, is ratelimiting
 	 * still needed here?
 	 */
-	mem_cgroup_flush_stats_ratelimited(eviction_memcg);
+	if (flush)
+		mem_cgroup_flush_stats_ratelimited(eviction_memcg);
 
 	eviction_lruvec = mem_cgroup_lruvec(eviction_memcg, pgdat);
 	refault = atomic_long_read(&eviction_lruvec->nonresident_age);
@@ -558,7 +566,7 @@ void workingset_refault(struct folio *folio, void *shadow)
 
 	mod_lruvec_state(lruvec, WORKINGSET_REFAULT_BASE + file, nr);
 
-	if (!workingset_test_recent(shadow, file, &workingset))
+	if (!workingset_test_recent(shadow, file, &workingset, true))
 		return;
 
 	folio_set_active(folio);