Merge tag 'mm-stable-2023-11-01-14-33' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:
 "Many singleton patches against the MM code. The patch series which are
  included in this merge do the following:

   - Kemeng Shi has contributed some compation maintenance work in the
     series 'Fixes and cleanups to compaction'

   - Joel Fernandes has a patchset ('Optimize mremap during mutual
     alignment within PMD') which fixes an obscure issue with mremap()'s
     pagetable handling during a subsequent exec(), based upon an
     implementation which Linus suggested

   - More DAMON/DAMOS maintenance and feature work from SeongJae Park i
     the following patch series:

	mm/damon: misc fixups for documents, comments and its tracepoint
	mm/damon: add a tracepoint for damos apply target regions
	mm/damon: provide pseudo-moving sum based access rate
	mm/damon: implement DAMOS apply intervals
	mm/damon/core-test: Fix memory leaks in core-test
	mm/damon/sysfs-schemes: Do DAMOS tried regions update for only one apply interval

   - In the series 'Do not try to access unaccepted memory' Adrian
     Hunter provides some fixups for the recently-added 'unaccepted
     memory' feature. To increase the feature's checking coverage. 'Plug
     a few gaps where RAM is exposed without checking if it is
     unaccepted memory'

   - In the series 'cleanups for lockless slab shrink' Qi Zheng has done
     some maintenance work which is preparation for the lockless slab
     shrinking code

   - Qi Zheng has redone the earlier (and reverted) attempt to make slab
     shrinking lockless in the series 'use refcount+RCU method to
     implement lockless slab shrink'

   - David Hildenbrand contributes some maintenance work for the rmap
     code in the series 'Anon rmap cleanups'

   - Kefeng Wang does more folio conversions and some maintenance work
     in the migration code. Series 'mm: migrate: more folio conversion
     and unification'

   - Matthew Wilcox has fixed an issue in the buffer_head code which was
     causing long stalls under some heavy memory/IO loads. Some cleanups
     were added on the way. Series 'Add and use bdev_getblk()'

   - In the series 'Use nth_page() in place of direct struct page
     manipulation' Zi Yan has fixed a potential issue with the direct
     manipulation of hugetlb page frames

   - In the series 'mm: hugetlb: Skip initialization of gigantic tail
     struct pages if freed by HVO' has improved our handling of gigantic
     pages in the hugetlb vmmemmep optimizaton code. This provides
     significant boot time improvements when significant amounts of
     gigantic pages are in use

   - Matthew Wilcox has sent the series 'Small hugetlb cleanups' - code
     rationalization and folio conversions in the hugetlb code

   - Yin Fengwei has improved mlock()'s handling of large folios in the
     series 'support large folio for mlock'

   - In the series 'Expose swapcache stat for memcg v1' Liu Shixin has
     added statistics for memcg v1 users which are available (and
     useful) under memcg v2

   - Florent Revest has enhanced the MDWE (Memory-Deny-Write-Executable)
     prctl so that userspace may direct the kernel to not automatically
     propagate the denial to child processes. The series is named 'MDWE
     without inheritance'

   - Kefeng Wang has provided the series 'mm: convert numa balancing
     functions to use a folio' which does what it says

   - In the series 'mm/ksm: add fork-exec support for prctl' Stefan
     Roesch makes is possible for a process to propagate KSM treatment
     across exec()

   - Huang Ying has enhanced memory tiering's calculation of memory
     distances. This is used to permit the dax/kmem driver to use 'high
     bandwidth memory' in addition to Optane Data Center Persistent
     Memory Modules (DCPMM). The series is named 'memory tiering:
     calculate abstract distance based on ACPI HMAT'

   - In the series 'Smart scanning mode for KSM' Stefan Roesch has
     optimized KSM by teaching it to retain and use some historical
     information from previous scans

   - Yosry Ahmed has fixed some inconsistencies in memcg statistics in
     the series 'mm: memcg: fix tracking of pending stats updates
     values'

   - In the series 'Implement IOCTL to get and optionally clear info
     about PTEs' Peter Xu has added an ioctl to /proc/<pid>/pagemap
     which permits us to atomically read-then-clear page softdirty
     state. This is mainly used by CRIU

   - Hugh Dickins contributed the series 'shmem,tmpfs: general
     maintenance', a bunch of relatively minor maintenance tweaks to
     this code

   - Matthew Wilcox has increased the use of the VMA lock over
     file-backed page faults in the series 'Handle more faults under the
     VMA lock'. Some rationalizations of the fault path became possible
     as a result

   - In the series 'mm/rmap: convert page_move_anon_rmap() to
     folio_move_anon_rmap()' David Hildenbrand has implemented some
     cleanups and folio conversions

   - In the series 'various improvements to the GUP interface' Lorenzo
     Stoakes has simplified and improved the GUP interface with an eye
     to providing groundwork for future improvements

   - Andrey Konovalov has sent along the series 'kasan: assorted fixes
     and improvements' which does those things

   - Some page allocator maintenance work from Kemeng Shi in the series
     'Two minor cleanups to break_down_buddy_pages'

   - In thes series 'New selftest for mm' Breno Leitao has developed
     another MM self test which tickles a race we had between madvise()
     and page faults

   - In the series 'Add folio_end_read' Matthew Wilcox provides cleanups
     and an optimization to the core pagecache code

   - Nhat Pham has added memcg accounting for hugetlb memory in the
     series 'hugetlb memcg accounting'

   - Cleanups and rationalizations to the pagemap code from Lorenzo
     Stoakes, in the series 'Abstract vma_merge() and split_vma()'

   - Audra Mitchell has fixed issues in the procfs page_owner code's new
     timestamping feature which was causing some misbehaviours. In the
     series 'Fix page_owner's use of free timestamps'

   - Lorenzo Stoakes has fixed the handling of new mappings of sealed
     files in the series 'permit write-sealed memfd read-only shared
     mappings'

   - Mike Kravetz has optimized the hugetlb vmemmap optimization in the
     series 'Batch hugetlb vmemmap modification operations'

   - Some buffer_head folio conversions and cleanups from Matthew Wilcox
     in the series 'Finish the create_empty_buffers() transition'

   - As a page allocator performance optimization Huang Ying has added
     automatic tuning to the allocator's per-cpu-pages feature, in the
     series 'mm: PCP high auto-tuning'

   - Roman Gushchin has contributed the patchset 'mm: improve
     performance of accounted kernel memory allocations' which improves
     their performance by ~30% as measured by a micro-benchmark

   - folio conversions from Kefeng Wang in the series 'mm: convert page
     cpupid functions to folios'

   - Some kmemleak fixups in Liu Shixin's series 'Some bugfix about
     kmemleak'

   - Qi Zheng has improved our handling of memoryless nodes by keeping
     them off the allocation fallback list. This is done in the series
     'handle memoryless nodes more appropriately'

   - khugepaged conversions from Vishal Moola in the series 'Some
     khugepaged folio conversions'"

[ bcachefs conflicts with the dynamically allocated shrinkers have been
  resolved as per Stephen Rothwell in

     https://lore.kernel.org/all/20230913093553.4290421e@canb.auug.org.au/

  with help from Qi Zheng.

  The clone3 test filtering conflict was half-arsed by yours truly ]

* tag 'mm-stable-2023-11-01-14-33' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (406 commits)
  mm/damon/sysfs: update monitoring target regions for online input commit
  mm/damon/sysfs: remove requested targets when online-commit inputs
  selftests: add a sanity check for zswap
  Documentation: maple_tree: fix word spelling error
  mm/vmalloc: fix the unchecked dereference warning in vread_iter()
  zswap: export compression failure stats
  Documentation: ubsan: drop "the" from article title
  mempolicy: migration attempt to match interleave nodes
  mempolicy: mmap_lock is not needed while migrating folios
  mempolicy: alloc_pages_mpol() for NUMA policy without vma
  mm: add page_rmappable_folio() wrapper
  mempolicy: remove confusing MPOL_MF_LAZY dead code
  mempolicy: mpol_shared_policy_init() without pseudo-vma
  mempolicy trivia: use pgoff_t in shared mempolicy tree
  mempolicy trivia: slightly more consistent naming
  mempolicy trivia: delete those ancient pr_debug()s
  mempolicy: fix migrate_pages(2) syscall return nr_failed
  kernfs: drop shared NUMA mempolicy hooks
  hugetlbfs: drop shared NUMA mempolicy pretence
  mm/damon/sysfs-test: add a unit test for damon_sysfs_set_targets()
  ...

1 files changed, 252 insertions, 49 deletions

diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
index 4b9734777f69..87818ee7f01d 100644
--- a/mm/hugetlb_vmemmap.c
+++ b/mm/hugetlb_vmemmap.c
@@ -13,6 +13,7 @@
 #include <linux/pgtable.h>
 #include <linux/moduleparam.h>
 #include <linux/bootmem_info.h>
+#include <linux/mmdebug.h>
 #include <asm/pgalloc.h>
 #include <asm/tlbflush.h>
 #include "hugetlb_vmemmap.h"
@@ -26,6 +27,8 @@
  * @reuse_addr:		the virtual address of the @reuse_page page.
  * @vmemmap_pages:	the list head of the vmemmap pages that can be freed
  *			or is mapped from.
+ * @flags:		used to modify behavior in vmemmap page table walking
+ *			operations.
  */
 struct vmemmap_remap_walk {
 	void			(*remap_pte)(pte_t *pte, unsigned long addr,
@@ -34,9 +37,15 @@ struct vmemmap_remap_walk {
 	struct page		*reuse_page;
 	unsigned long		reuse_addr;
 	struct list_head	*vmemmap_pages;
+
+/* Skip the TLB flush when we split the PMD */
+#define VMEMMAP_SPLIT_NO_TLB_FLUSH	BIT(0)
+/* Skip the TLB flush when we remap the PTE */
+#define VMEMMAP_REMAP_NO_TLB_FLUSH	BIT(1)
+	unsigned long		flags;
 };
 
-static int split_vmemmap_huge_pmd(pmd_t *pmd, unsigned long start)
+static int split_vmemmap_huge_pmd(pmd_t *pmd, unsigned long start, bool flush)
 {
 	pmd_t __pmd;
 	int i;
@@ -79,7 +88,8 @@ static int split_vmemmap_huge_pmd(pmd_t *pmd, unsigned long start)
 		/* Make pte visible before pmd. See comment in pmd_install(). */
 		smp_wmb();
 		pmd_populate_kernel(&init_mm, pmd, pgtable);
-		flush_tlb_kernel_range(start, start + PMD_SIZE);
+		if (flush)
+			flush_tlb_kernel_range(start, start + PMD_SIZE);
 	} else {
 		pte_free_kernel(&init_mm, pgtable);
 	}
@@ -126,11 +136,20 @@ static int vmemmap_pmd_range(pud_t *pud, unsigned long addr,
 	do {
 		int ret;
 
-		ret = split_vmemmap_huge_pmd(pmd, addr & PMD_MASK);
+		ret = split_vmemmap_huge_pmd(pmd, addr & PMD_MASK,
+				!(walk->flags & VMEMMAP_SPLIT_NO_TLB_FLUSH));
 		if (ret)
 			return ret;
 
 		next = pmd_addr_end(addr, end);
+
+		/*
+		 * We are only splitting, not remapping the hugetlb vmemmap
+		 * pages.
+		 */
+		if (!walk->remap_pte)
+			continue;
+
 		vmemmap_pte_range(pmd, addr, next, walk);
 	} while (pmd++, addr = next, addr != end);
 
@@ -197,7 +216,8 @@ static int vmemmap_remap_range(unsigned long start, unsigned long end,
 			return ret;
 	} while (pgd++, addr = next, addr != end);
 
-	flush_tlb_kernel_range(start, end);
+	if (walk->remap_pte && !(walk->flags & VMEMMAP_REMAP_NO_TLB_FLUSH))
+		flush_tlb_kernel_range(start, end);
 
 	return 0;
 }
@@ -250,7 +270,7 @@ static void vmemmap_remap_pte(pte_t *pte, unsigned long addr,
 	}
 
 	entry = mk_pte(walk->reuse_page, pgprot);
-	list_add_tail(&page->lru, walk->vmemmap_pages);
+	list_add(&page->lru, walk->vmemmap_pages);
 	set_pte_at(&init_mm, addr, pte, entry);
 }
 
@@ -297,6 +317,36 @@ static void vmemmap_restore_pte(pte_t *pte, unsigned long addr,
 }
 
 /**
+ * vmemmap_remap_split - split the vmemmap virtual address range [@start, @end)
+ *                      backing PMDs of the directmap into PTEs
+ * @start:     start address of the vmemmap virtual address range that we want
+ *             to remap.
+ * @end:       end address of the vmemmap virtual address range that we want to
+ *             remap.
+ * @reuse:     reuse address.
+ *
+ * Return: %0 on success, negative error code otherwise.
+ */
+static int vmemmap_remap_split(unsigned long start, unsigned long end,
+				unsigned long reuse)
+{
+	int ret;
+	struct vmemmap_remap_walk walk = {
+		.remap_pte	= NULL,
+		.flags		= VMEMMAP_SPLIT_NO_TLB_FLUSH,
+	};
+
+	/* See the comment in the vmemmap_remap_free(). */
+	BUG_ON(start - reuse != PAGE_SIZE);
+
+	mmap_read_lock(&init_mm);
+	ret = vmemmap_remap_range(reuse, end, &walk);
+	mmap_read_unlock(&init_mm);
+
+	return ret;
+}
+
+/**
  * vmemmap_remap_free - remap the vmemmap virtual address range [@start, @end)
  *			to the page which @reuse is mapped to, then free vmemmap
  *			which the range are mapped to.
@@ -305,22 +355,26 @@ static void vmemmap_restore_pte(pte_t *pte, unsigned long addr,
  * @end:	end address of the vmemmap virtual address range that we want to
  *		remap.
  * @reuse:	reuse address.
+ * @vmemmap_pages: list to deposit vmemmap pages to be freed.  It is callers
+ *		responsibility to free pages.
+ * @flags:	modifications to vmemmap_remap_walk flags
  *
  * Return: %0 on success, negative error code otherwise.
  */
 static int vmemmap_remap_free(unsigned long start, unsigned long end,
-			      unsigned long reuse)
+			      unsigned long reuse,
+			      struct list_head *vmemmap_pages,
+			      unsigned long flags)
 {
 	int ret;
-	LIST_HEAD(vmemmap_pages);
 	struct vmemmap_remap_walk walk = {
 		.remap_pte	= vmemmap_remap_pte,
 		.reuse_addr	= reuse,
-		.vmemmap_pages	= &vmemmap_pages,
+		.vmemmap_pages	= vmemmap_pages,
+		.flags		= flags,
 	};
-	int nid = page_to_nid((struct page *)start);
-	gfp_t gfp_mask = GFP_KERNEL | __GFP_THISNODE | __GFP_NORETRY |
-			__GFP_NOWARN;
+	int nid = page_to_nid((struct page *)reuse);
+	gfp_t gfp_mask = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN;
 
 	/*
 	 * Allocate a new head vmemmap page to avoid breaking a contiguous
@@ -334,7 +388,7 @@ static int vmemmap_remap_free(unsigned long start, unsigned long end,
 	if (walk.reuse_page) {
 		copy_page(page_to_virt(walk.reuse_page),
 			  (void *)walk.reuse_addr);
-		list_add(&walk.reuse_page->lru, &vmemmap_pages);
+		list_add(&walk.reuse_page->lru, vmemmap_pages);
 	}
 
 	/*
@@ -365,22 +419,21 @@ static int vmemmap_remap_free(unsigned long start, unsigned long end,
 		walk = (struct vmemmap_remap_walk) {
 			.remap_pte	= vmemmap_restore_pte,
 			.reuse_addr	= reuse,
-			.vmemmap_pages	= &vmemmap_pages,
+			.vmemmap_pages	= vmemmap_pages,
+			.flags		= 0,
 		};
 
 		vmemmap_remap_range(reuse, end, &walk);
 	}
 	mmap_read_unlock(&init_mm);
 
-	free_vmemmap_page_list(&vmemmap_pages);
-
 	return ret;
 }
 
 static int alloc_vmemmap_page_list(unsigned long start, unsigned long end,
 				   struct list_head *list)
 {
-	gfp_t gfp_mask = GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_THISNODE;
+	gfp_t gfp_mask = GFP_KERNEL | __GFP_RETRY_MAYFAIL;
 	unsigned long nr_pages = (end - start) >> PAGE_SHIFT;
 	int nid = page_to_nid((struct page *)start);
 	struct page *page, *next;
@@ -389,7 +442,7 @@ static int alloc_vmemmap_page_list(unsigned long start, unsigned long end,
 		page = alloc_pages_node(nid, gfp_mask, 0);
 		if (!page)
 			goto out;
-		list_add_tail(&page->lru, list);
+		list_add(&page->lru, list);
 	}
 
 	return 0;
@@ -408,17 +461,19 @@ out:
  * @end:	end address of the vmemmap virtual address range that we want to
  *		remap.
  * @reuse:	reuse address.
+ * @flags:	modifications to vmemmap_remap_walk flags
  *
  * Return: %0 on success, negative error code otherwise.
  */
 static int vmemmap_remap_alloc(unsigned long start, unsigned long end,
-			       unsigned long reuse)
+			       unsigned long reuse, unsigned long flags)
 {
 	LIST_HEAD(vmemmap_pages);
 	struct vmemmap_remap_walk walk = {
 		.remap_pte	= vmemmap_restore_pte,
 		.reuse_addr	= reuse,
 		.vmemmap_pages	= &vmemmap_pages,
+		.flags		= flags,
 	};
 
 	/* See the comment in the vmemmap_remap_free(). */
@@ -440,23 +495,15 @@ EXPORT_SYMBOL(hugetlb_optimize_vmemmap_key);
 static bool vmemmap_optimize_enabled = IS_ENABLED(CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON);
 core_param(hugetlb_free_vmemmap, vmemmap_optimize_enabled, bool, 0);
 
-/**
- * hugetlb_vmemmap_restore - restore previously optimized (by
- *			     hugetlb_vmemmap_optimize()) vmemmap pages which
- *			     will be reallocated and remapped.
- * @h:		struct hstate.
- * @head:	the head page whose vmemmap pages will be restored.
- *
- * Return: %0 if @head's vmemmap pages have been reallocated and remapped,
- * negative error code otherwise.
- */
-int hugetlb_vmemmap_restore(const struct hstate *h, struct page *head)
+static int __hugetlb_vmemmap_restore_folio(const struct hstate *h, struct folio *folio, unsigned long flags)
 {
 	int ret;
+	struct page *head = &folio->page;
 	unsigned long vmemmap_start = (unsigned long)head, vmemmap_end;
 	unsigned long vmemmap_reuse;
 
-	if (!HPageVmemmapOptimized(head))
+	VM_WARN_ON_ONCE(!PageHuge(head));
+	if (!folio_test_hugetlb_vmemmap_optimized(folio))
 		return 0;
 
 	vmemmap_end	= vmemmap_start + hugetlb_vmemmap_size(h);
@@ -470,18 +517,77 @@ int hugetlb_vmemmap_restore(const struct hstate *h, struct page *head)
 	 * When a HugeTLB page is freed to the buddy allocator, previously
 	 * discarded vmemmap pages must be allocated and remapping.
 	 */
-	ret = vmemmap_remap_alloc(vmemmap_start, vmemmap_end, vmemmap_reuse);
+	ret = vmemmap_remap_alloc(vmemmap_start, vmemmap_end, vmemmap_reuse, flags);
 	if (!ret) {
-		ClearHPageVmemmapOptimized(head);
+		folio_clear_hugetlb_vmemmap_optimized(folio);
 		static_branch_dec(&hugetlb_optimize_vmemmap_key);
 	}
 
 	return ret;
 }
 
+/**
+ * hugetlb_vmemmap_restore_folio - restore previously optimized (by
+ *				hugetlb_vmemmap_optimize_folio()) vmemmap pages which
+ *				will be reallocated and remapped.
+ * @h:		struct hstate.
+ * @folio:     the folio whose vmemmap pages will be restored.
+ *
+ * Return: %0 if @folio's vmemmap pages have been reallocated and remapped,
+ * negative error code otherwise.
+ */
+int hugetlb_vmemmap_restore_folio(const struct hstate *h, struct folio *folio)
+{
+	return __hugetlb_vmemmap_restore_folio(h, folio, 0);
+}
+
+/**
+ * hugetlb_vmemmap_restore_folios - restore vmemmap for every folio on the list.
+ * @h:			hstate.
+ * @folio_list:		list of folios.
+ * @non_hvo_folios:	Output list of folios for which vmemmap exists.
+ *
+ * Return: number of folios for which vmemmap was restored, or an error code
+ *		if an error was encountered restoring vmemmap for a folio.
+ *		Folios that have vmemmap are moved to the non_hvo_folios
+ *		list.  Processing of entries stops when the first error is
+ *		encountered. The folio that experienced the error and all
+ *		non-processed folios will remain on folio_list.
+ */
+long hugetlb_vmemmap_restore_folios(const struct hstate *h,
+					struct list_head *folio_list,
+					struct list_head *non_hvo_folios)
+{
+	struct folio *folio, *t_folio;
+	long restored = 0;
+	long ret = 0;
+
+	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,
+						VMEMMAP_REMAP_NO_TLB_FLUSH);
+			if (ret)
+				break;
+			restored++;
+		}
+
+		/* Add non-optimized folios to output list */
+		list_move(&folio->lru, non_hvo_folios);
+	}
+
+	if (restored)
+		flush_tlb_all();
+	if (!ret)
+		ret = restored;
+	return ret;
+}
+
 /* Return true iff a HugeTLB whose vmemmap should and can be optimized. */
 static bool vmemmap_should_optimize(const struct hstate *h, const struct page *head)
 {
+	if (HPageVmemmapOptimized((struct page *)head))
+		return false;
+
 	if (!READ_ONCE(vmemmap_optimize_enabled))
 		return false;
 
@@ -535,39 +641,136 @@ static bool vmemmap_should_optimize(const struct hstate *h, const struct page *h
 	return true;
 }
 
+static int __hugetlb_vmemmap_optimize_folio(const struct hstate *h,
+					struct folio *folio,
+					struct list_head *vmemmap_pages,
+					unsigned long flags)
+{
+	int ret = 0;
+	struct page *head = &folio->page;
+	unsigned long vmemmap_start = (unsigned long)head, vmemmap_end;
+	unsigned long vmemmap_reuse;
+
+	VM_WARN_ON_ONCE(!PageHuge(head));
+	if (!vmemmap_should_optimize(h, head))
+		return ret;
+
+	static_branch_inc(&hugetlb_optimize_vmemmap_key);
+	/*
+	 * Very Subtle
+	 * If VMEMMAP_REMAP_NO_TLB_FLUSH is set, TLB flushing is not performed
+	 * immediately after remapping.  As a result, subsequent accesses
+	 * and modifications to struct pages associated with the hugetlb
+	 * page could be to the OLD struct pages.  Set the vmemmap optimized
+	 * flag here so that it is copied to the new head page.  This keeps
+	 * the old and new struct pages in sync.
+	 * If there is an error during optimization, we will immediately FLUSH
+	 * the TLB and clear the flag below.
+	 */
+	folio_set_hugetlb_vmemmap_optimized(folio);
+
+	vmemmap_end	= vmemmap_start + hugetlb_vmemmap_size(h);
+	vmemmap_reuse	= vmemmap_start;
+	vmemmap_start	+= HUGETLB_VMEMMAP_RESERVE_SIZE;
+
+	/*
+	 * Remap the vmemmap virtual address range [@vmemmap_start, @vmemmap_end)
+	 * to the page which @vmemmap_reuse is mapped to.  Add pages previously
+	 * mapping the range to vmemmap_pages list so that they can be freed by
+	 * the caller.
+	 */
+	ret = vmemmap_remap_free(vmemmap_start, vmemmap_end, vmemmap_reuse,
+							vmemmap_pages, flags);
+	if (ret) {
+		static_branch_dec(&hugetlb_optimize_vmemmap_key);
+		folio_clear_hugetlb_vmemmap_optimized(folio);
+	}
+
+	return ret;
+}
+
 /**
- * hugetlb_vmemmap_optimize - optimize @head page's vmemmap pages.
+ * hugetlb_vmemmap_optimize_folio - optimize @folio's vmemmap pages.
  * @h:		struct hstate.
- * @head:	the head page whose vmemmap pages will be optimized.
+ * @folio:     the folio whose vmemmap pages will be optimized.
  *
- * This function only tries to optimize @head's vmemmap pages and does not
+ * This function only tries to optimize @folio's vmemmap pages and does not
  * guarantee that the optimization will succeed after it returns. The caller
- * can use HPageVmemmapOptimized(@head) to detect if @head's vmemmap pages
- * have been optimized.
+ * can use folio_test_hugetlb_vmemmap_optimized(@folio) to detect if @folio's
+ * vmemmap pages have been optimized.
  */
-void hugetlb_vmemmap_optimize(const struct hstate *h, struct page *head)
+void hugetlb_vmemmap_optimize_folio(const struct hstate *h, struct folio *folio)
+{
+	LIST_HEAD(vmemmap_pages);
+
+	__hugetlb_vmemmap_optimize_folio(h, folio, &vmemmap_pages, 0);
+	free_vmemmap_page_list(&vmemmap_pages);
+}
+
+static int hugetlb_vmemmap_split(const struct hstate *h, struct page *head)
 {
 	unsigned long vmemmap_start = (unsigned long)head, vmemmap_end;
 	unsigned long vmemmap_reuse;
 
 	if (!vmemmap_should_optimize(h, head))
-		return;
-
-	static_branch_inc(&hugetlb_optimize_vmemmap_key);
+		return 0;
 
 	vmemmap_end	= vmemmap_start + hugetlb_vmemmap_size(h);
 	vmemmap_reuse	= vmemmap_start;
 	vmemmap_start	+= HUGETLB_VMEMMAP_RESERVE_SIZE;
 
 	/*
-	 * Remap the vmemmap virtual address range [@vmemmap_start, @vmemmap_end)
-	 * to the page which @vmemmap_reuse is mapped to, then free the pages
-	 * which the range [@vmemmap_start, @vmemmap_end] is mapped to.
+	 * Split PMDs on the vmemmap virtual address range [@vmemmap_start,
+	 * @vmemmap_end]
 	 */
-	if (vmemmap_remap_free(vmemmap_start, vmemmap_end, vmemmap_reuse))
-		static_branch_dec(&hugetlb_optimize_vmemmap_key);
-	else
-		SetHPageVmemmapOptimized(head);
+	return vmemmap_remap_split(vmemmap_start, vmemmap_end, vmemmap_reuse);
+}
+
+void hugetlb_vmemmap_optimize_folios(struct hstate *h, struct list_head *folio_list)
+{
+	struct folio *folio;
+	LIST_HEAD(vmemmap_pages);
+
+	list_for_each_entry(folio, folio_list, lru) {
+		int ret = hugetlb_vmemmap_split(h, &folio->page);
+
+		/*
+		 * Spliting the PMD requires allocating a page, thus lets fail
+		 * early once we encounter the first OOM. No point in retrying
+		 * as it can be dynamically done on remap with the memory
+		 * we get back from the vmemmap deduplication.
+		 */
+		if (ret == -ENOMEM)
+			break;
+	}
+
+	flush_tlb_all();
+
+	list_for_each_entry(folio, folio_list, lru) {
+		int ret = __hugetlb_vmemmap_optimize_folio(h, folio,
+						&vmemmap_pages,
+						VMEMMAP_REMAP_NO_TLB_FLUSH);
+
+		/*
+		 * Pages to be freed may have been accumulated.  If we
+		 * encounter an ENOMEM,  free what we have and try again.
+		 * This can occur in the case that both spliting fails
+		 * halfway and head page allocation also failed. In this
+		 * case __hugetlb_vmemmap_optimize_folio() would free memory
+		 * allowing more vmemmap remaps to occur.
+		 */
+		if (ret == -ENOMEM && !list_empty(&vmemmap_pages)) {
+			flush_tlb_all();
+			free_vmemmap_page_list(&vmemmap_pages);
+			INIT_LIST_HEAD(&vmemmap_pages);
+			__hugetlb_vmemmap_optimize_folio(h, folio,
+						&vmemmap_pages,
+						VMEMMAP_REMAP_NO_TLB_FLUSH);
+		}
+	}
+
+	flush_tlb_all();
+	free_vmemmap_page_list(&vmemmap_pages);
 }
 
 static struct ctl_table hugetlb_vmemmap_sysctls[] = {
@@ -586,7 +789,7 @@ static int __init hugetlb_vmemmap_init(void)
 	const struct hstate *h;
 
 	/* HUGETLB_VMEMMAP_RESERVE_SIZE should cover all used struct pages */
-	BUILD_BUG_ON(__NR_USED_SUBPAGE * sizeof(struct page) > HUGETLB_VMEMMAP_RESERVE_SIZE);
+	BUILD_BUG_ON(__NR_USED_SUBPAGE > HUGETLB_VMEMMAP_RESERVE_PAGES);
 
 	for_each_hstate(h) {
 		if (hugetlb_vmemmap_optimizable(h)) {