Merge tag 'mm-stable-2024-09-20-02-31' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:
 "Along with the usual shower of singleton patches, notable patch series
  in this pull request are:

   - "Align kvrealloc() with krealloc()" from Danilo Krummrich. Adds
     consistency to the APIs and behaviour of these two core allocation
     functions. This also simplifies/enables Rustification.

   - "Some cleanups for shmem" from Baolin Wang. No functional changes -
     mode code reuse, better function naming, logic simplifications.

   - "mm: some small page fault cleanups" from Josef Bacik. No
     functional changes - code cleanups only.

   - "Various memory tiering fixes" from Zi Yan. A small fix and a
     little cleanup.

   - "mm/swap: remove boilerplate" from Yu Zhao. Code cleanups and
     simplifications and .text shrinkage.

   - "Kernel stack usage histogram" from Pasha Tatashin and Shakeel
     Butt. This is a feature, it adds new feilds to /proc/vmstat such as

       $ grep kstack /proc/vmstat
       kstack_1k 3
       kstack_2k 188
       kstack_4k 11391
       kstack_8k 243
       kstack_16k 0

     which tells us that 11391 processes used 4k of stack while none at
     all used 16k. Useful for some system tuning things, but
     partivularly useful for "the dynamic kernel stack project".

   - "kmemleak: support for percpu memory leak detect" from Pavel
     Tikhomirov. Teaches kmemleak to detect leaksage of percpu memory.

   - "mm: memcg: page counters optimizations" from Roman Gushchin. "3
     independent small optimizations of page counters".

   - "mm: split PTE/PMD PT table Kconfig cleanups+clarifications" from
     David Hildenbrand. Improves PTE/PMD splitlock detection, makes
     powerpc/8xx work correctly by design rather than by accident.

   - "mm: remove arch_make_page_accessible()" from David Hildenbrand.
     Some folio conversions which make arch_make_page_accessible()
     unneeded.

   - "mm, memcg: cg2 memory{.swap,}.peak write handlers" fro David
     Finkel. Cleans up and fixes our handling of the resetting of the
     cgroup/process peak-memory-use detector.

   - "Make core VMA operations internal and testable" from Lorenzo
     Stoakes. Rationalizaion and encapsulation of the VMA manipulation
     APIs. With a view to better enable testing of the VMA functions,
     even from a userspace-only harness.

   - "mm: zswap: fixes for global shrinker" from Takero Funaki. Fix
     issues in the zswap global shrinker, resulting in improved
     performance.

   - "mm: print the promo watermark in zoneinfo" from Kaiyang Zhao. Fill
     in some missing info in /proc/zoneinfo.

   - "mm: replace follow_page() by folio_walk" from David Hildenbrand.
     Code cleanups and rationalizations (conversion to folio_walk())
     resulting in the removal of follow_page().

   - "improving dynamic zswap shrinker protection scheme" from Nhat
     Pham. Some tuning to improve zswap's dynamic shrinker. Significant
     reductions in swapin and improvements in performance are shown.

   - "mm: Fix several issues with unaccepted memory" from Kirill
     Shutemov. Improvements to the new unaccepted memory feature,

   - "mm/mprotect: Fix dax puds" from Peter Xu. Implements mprotect on
     DAX PUDs. This was missing, although nobody seems to have notied
     yet.

   - "Introduce a store type enum for the Maple tree" from Sidhartha
     Kumar. Cleanups and modest performance improvements for the maple
     tree library code.

   - "memcg: further decouple v1 code from v2" from Shakeel Butt. Move
     more cgroup v1 remnants away from the v2 memcg code.

   - "memcg: initiate deprecation of v1 features" from Shakeel Butt.
     Adds various warnings telling users that memcg v1 features are
     deprecated.

   - "mm: swap: mTHP swap allocator base on swap cluster order" from
     Chris Li. Greatly improves the success rate of the mTHP swap
     allocation.

   - "mm: introduce numa_memblks" from Mike Rapoport. Moves various
     disparate per-arch implementations of numa_memblk code into generic
     code.

   - "mm: batch free swaps for zap_pte_range()" from Barry Song. Greatly
     improves the performance of munmap() of swap-filled ptes.

   - "support large folio swap-out and swap-in for shmem" from Baolin
     Wang. With this series we no longer split shmem large folios into
     simgle-page folios when swapping out shmem.

   - "mm/hugetlb: alloc/free gigantic folios" from Yu Zhao. Nice
     performance improvements and code reductions for gigantic folios.

   - "support shmem mTHP collapse" from Baolin Wang. Adds support for
     khugepaged's collapsing of shmem mTHP folios.

   - "mm: Optimize mseal checks" from Pedro Falcato. Fixes an mprotect()
     performance regression due to the addition of mseal().

   - "Increase the number of bits available in page_type" from Matthew
     Wilcox. Increases the number of bits available in page_type!

   - "Simplify the page flags a little" from Matthew Wilcox. Many legacy
     page flags are now folio flags, so the page-based flags and their
     accessors/mutators can be removed.

   - "mm: store zero pages to be swapped out in a bitmap" from Usama
     Arif. An optimization which permits us to avoid writing/reading
     zero-filled zswap pages to backing store.

   - "Avoid MAP_FIXED gap exposure" from Liam Howlett. Fixes a race
     window which occurs when a MAP_FIXED operqtion is occurring during
     an unrelated vma tree walk.

   - "mm: remove vma_merge()" from Lorenzo Stoakes. Major rotorooting of
     the vma_merge() functionality, making ot cleaner, more testable and
     better tested.

   - "misc fixups for DAMON {self,kunit} tests" from SeongJae Park.
     Minor fixups of DAMON selftests and kunit tests.

   - "mm: memory_hotplug: improve do_migrate_range()" from Kefeng Wang.
     Code cleanups and folio conversions.

   - "Shmem mTHP controls and stats improvements" from Ryan Roberts.
     Cleanups for shmem controls and stats.

   - "mm: count the number of anonymous THPs per size" from Barry Song.
     Expose additional anon THP stats to userspace for improved tuning.

   - "mm: finish isolate/putback_lru_page()" from Kefeng Wang: more
     folio conversions and removal of now-unused page-based APIs.

   - "replace per-quota region priorities histogram buffer with
     per-context one" from SeongJae Park. DAMON histogram
     rationalization.

   - "Docs/damon: update GitHub repo URLs and maintainer-profile" from
     SeongJae Park. DAMON documentation updates.

   - "mm/vdpa: correct misuse of non-direct-reclaim __GFP_NOFAIL and
     improve related doc and warn" from Jason Wang: fixes usage of page
     allocator __GFP_NOFAIL and GFP_ATOMIC flags.

   - "mm: split underused THPs" from Yu Zhao. Improve THP=always policy.
     This was overprovisioning THPs in sparsely accessed memory areas.

   - "zram: introduce custom comp backends API" frm Sergey Senozhatsky.
     Add support for zram run-time compression algorithm tuning.

   - "mm: Care about shadow stack guard gap when getting an unmapped
     area" from Mark Brown. Fix up the various arch_get_unmapped_area()
     implementations to better respect guard areas.

   - "Improve mem_cgroup_iter()" from Kinsey Ho. Improve the reliability
     of mem_cgroup_iter() and various code cleanups.

   - "mm: Support huge pfnmaps" from Peter Xu. Extends the usage of huge
     pfnmap support.

   - "resource: Fix region_intersects() vs add_memory_driver_managed()"
     from Huang Ying. Fix a bug in region_intersects() for systems with
     CXL memory.

   - "mm: hwpoison: two more poison recovery" from Kefeng Wang. Teaches
     a couple more code paths to correctly recover from the encountering
     of poisoned memry.

   - "mm: enable large folios swap-in support" from Barry Song. Support
     the swapin of mTHP memory into appropriately-sized folios, rather
     than into single-page folios"

* tag 'mm-stable-2024-09-20-02-31' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (416 commits)
  zram: free secondary algorithms names
  uprobes: turn xol_area->pages[2] into xol_area->page
  uprobes: introduce the global struct vm_special_mapping xol_mapping
  Revert "uprobes: use vm_special_mapping close() functionality"
  mm: support large folios swap-in for sync io devices
  mm: add nr argument in mem_cgroup_swapin_uncharge_swap() helper to support large folios
  mm: fix swap_read_folio_zeromap() for large folios with partial zeromap
  mm/debug_vm_pgtable: Use pxdp_get() for accessing page table entries
  set_memory: add __must_check to generic stubs
  mm/vma: return the exact errno in vms_gather_munmap_vmas()
  memcg: cleanup with !CONFIG_MEMCG_V1
  mm/show_mem.c: report alloc tags in human readable units
  mm: support poison recovery from copy_present_page()
  mm: support poison recovery from do_cow_fault()
  resource, kunit: add test case for region_intersects()
  resource: make alloc_free_mem_region() works for iomem_resource
  mm: z3fold: deprecate CONFIG_Z3FOLD
  vfio/pci: implement huge_fault support
  mm/arm64: support large pfn mappings
  mm/x86: support large pfn mappings
  ...

1 files changed, 194 insertions, 1962 deletions

diff --git a/mm/mmap.c b/mm/mmap.c
index 6ddb278a5ee8..ee8f91eaadb9 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -76,16 +76,6 @@ int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS;
 static bool ignore_rlimit_data;
 core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644);
 
-static void unmap_region(struct mm_struct *mm, struct ma_state *mas,
-		struct vm_area_struct *vma, struct vm_area_struct *prev,
-		struct vm_area_struct *next, unsigned long start,
-		unsigned long end, unsigned long tree_end, bool mm_wr_locked);
-
-static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
-{
-	return pgprot_modify(oldprot, vm_get_page_prot(vm_flags));
-}
-
 /* Update vma->vm_page_prot to reflect vma->vm_flags. */
 void vma_set_page_prot(struct vm_area_struct *vma)
 {
@@ -102,100 +92,6 @@ void vma_set_page_prot(struct vm_area_struct *vma)
 }
 
 /*
- * Requires inode->i_mapping->i_mmap_rwsem
- */
-static void __remove_shared_vm_struct(struct vm_area_struct *vma,
-				      struct address_space *mapping)
-{
-	if (vma_is_shared_maywrite(vma))
-		mapping_unmap_writable(mapping);
-
-	flush_dcache_mmap_lock(mapping);
-	vma_interval_tree_remove(vma, &mapping->i_mmap);
-	flush_dcache_mmap_unlock(mapping);
-}
-
-/*
- * Unlink a file-based vm structure from its interval tree, to hide
- * vma from rmap and vmtruncate before freeing its page tables.
- */
-void unlink_file_vma(struct vm_area_struct *vma)
-{
-	struct file *file = vma->vm_file;
-
-	if (file) {
-		struct address_space *mapping = file->f_mapping;
-		i_mmap_lock_write(mapping);
-		__remove_shared_vm_struct(vma, mapping);
-		i_mmap_unlock_write(mapping);
-	}
-}
-
-void unlink_file_vma_batch_init(struct unlink_vma_file_batch *vb)
-{
-	vb->count = 0;
-}
-
-static void unlink_file_vma_batch_process(struct unlink_vma_file_batch *vb)
-{
-	struct address_space *mapping;
-	int i;
-
-	mapping = vb->vmas[0]->vm_file->f_mapping;
-	i_mmap_lock_write(mapping);
-	for (i = 0; i < vb->count; i++) {
-		VM_WARN_ON_ONCE(vb->vmas[i]->vm_file->f_mapping != mapping);
-		__remove_shared_vm_struct(vb->vmas[i], mapping);
-	}
-	i_mmap_unlock_write(mapping);
-
-	unlink_file_vma_batch_init(vb);
-}
-
-void unlink_file_vma_batch_add(struct unlink_vma_file_batch *vb,
-			       struct vm_area_struct *vma)
-{
-	if (vma->vm_file == NULL)
-		return;
-
-	if ((vb->count > 0 && vb->vmas[0]->vm_file != vma->vm_file) ||
-	    vb->count == ARRAY_SIZE(vb->vmas))
-		unlink_file_vma_batch_process(vb);
-
-	vb->vmas[vb->count] = vma;
-	vb->count++;
-}
-
-void unlink_file_vma_batch_final(struct unlink_vma_file_batch *vb)
-{
-	if (vb->count > 0)
-		unlink_file_vma_batch_process(vb);
-}
-
-/*
- * Close a vm structure and free it.
- */
-static void remove_vma(struct vm_area_struct *vma, bool unreachable)
-{
-	might_sleep();
-	if (vma->vm_ops && vma->vm_ops->close)
-		vma->vm_ops->close(vma);
-	if (vma->vm_file)
-		fput(vma->vm_file);
-	mpol_put(vma_policy(vma));
-	if (unreachable)
-		__vm_area_free(vma);
-	else
-		vm_area_free(vma);
-}
-
-static inline struct vm_area_struct *vma_prev_limit(struct vma_iterator *vmi,
-						    unsigned long min)
-{
-	return mas_prev(&vmi->mas, min);
-}
-
-/*
  * check_brk_limits() - Use platform specific check of range & verify mlock
  * limits.
  * @addr: The address to check
@@ -273,11 +169,12 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
 			goto out; /* mapping intersects with an existing non-brk vma. */
 		/*
 		 * mm->brk must be protected by write mmap_lock.
-		 * do_vma_munmap() will drop the lock on success,  so update it
-		 * before calling do_vma_munmap().
+		 * do_vmi_align_munmap() will drop the lock on success,  so
+		 * update it before calling do_vma_munmap().
 		 */
 		mm->brk = brk;
-		if (do_vma_munmap(&vmi, brkvma, newbrk, oldbrk, &uf, true))
+		if (do_vmi_align_munmap(&vmi, brkvma, mm, newbrk, oldbrk, &uf,
+					/* unlock = */ true))
 			goto out;
 
 		goto success_unlocked;
@@ -318,875 +215,6 @@ out:
 	return origbrk;
 }
 
-#if defined(CONFIG_DEBUG_VM_MAPLE_TREE)
-static void validate_mm(struct mm_struct *mm)
-{
-	int bug = 0;
-	int i = 0;
-	struct vm_area_struct *vma;
-	VMA_ITERATOR(vmi, mm, 0);
-
-	mt_validate(&mm->mm_mt);
-	for_each_vma(vmi, vma) {
-#ifdef CONFIG_DEBUG_VM_RB
-		struct anon_vma *anon_vma = vma->anon_vma;
-		struct anon_vma_chain *avc;
-#endif
-		unsigned long vmi_start, vmi_end;
-		bool warn = 0;
-
-		vmi_start = vma_iter_addr(&vmi);
-		vmi_end = vma_iter_end(&vmi);
-		if (VM_WARN_ON_ONCE_MM(vma->vm_end != vmi_end, mm))
-			warn = 1;
-
-		if (VM_WARN_ON_ONCE_MM(vma->vm_start != vmi_start, mm))
-			warn = 1;
-
-		if (warn) {
-			pr_emerg("issue in %s\n", current->comm);
-			dump_stack();
-			dump_vma(vma);
-			pr_emerg("tree range: %px start %lx end %lx\n", vma,
-				 vmi_start, vmi_end - 1);
-			vma_iter_dump_tree(&vmi);
-		}
-
-#ifdef CONFIG_DEBUG_VM_RB
-		if (anon_vma) {
-			anon_vma_lock_read(anon_vma);
-			list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
-				anon_vma_interval_tree_verify(avc);
-			anon_vma_unlock_read(anon_vma);
-		}
-#endif
-		i++;
-	}
-	if (i != mm->map_count) {
-		pr_emerg("map_count %d vma iterator %d\n", mm->map_count, i);
-		bug = 1;
-	}
-	VM_BUG_ON_MM(bug, mm);
-}
-
-#else /* !CONFIG_DEBUG_VM_MAPLE_TREE */
-#define validate_mm(mm) do { } while (0)
-#endif /* CONFIG_DEBUG_VM_MAPLE_TREE */
-
-/*
- * vma has some anon_vma assigned, and is already inserted on that
- * anon_vma's interval trees.
- *
- * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
- * vma must be removed from the anon_vma's interval trees using
- * anon_vma_interval_tree_pre_update_vma().
- *
- * After the update, the vma will be reinserted using
- * anon_vma_interval_tree_post_update_vma().
- *
- * The entire update must be protected by exclusive mmap_lock and by
- * the root anon_vma's mutex.
- */
-static inline void
-anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
-{
-	struct anon_vma_chain *avc;
-
-	list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
-		anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
-}
-
-static inline void
-anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
-{
-	struct anon_vma_chain *avc;
-
-	list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
-		anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
-}
-
-static unsigned long count_vma_pages_range(struct mm_struct *mm,
-		unsigned long addr, unsigned long end)
-{
-	VMA_ITERATOR(vmi, mm, addr);
-	struct vm_area_struct *vma;
-	unsigned long nr_pages = 0;
-
-	for_each_vma_range(vmi, vma, end) {
-		unsigned long vm_start = max(addr, vma->vm_start);
-		unsigned long vm_end = min(end, vma->vm_end);
-
-		nr_pages += PHYS_PFN(vm_end - vm_start);
-	}
-
-	return nr_pages;
-}
-
-static void __vma_link_file(struct vm_area_struct *vma,
-			    struct address_space *mapping)
-{
-	if (vma_is_shared_maywrite(vma))
-		mapping_allow_writable(mapping);
-
-	flush_dcache_mmap_lock(mapping);
-	vma_interval_tree_insert(vma, &mapping->i_mmap);
-	flush_dcache_mmap_unlock(mapping);
-}
-
-static void vma_link_file(struct vm_area_struct *vma)
-{
-	struct file *file = vma->vm_file;
-	struct address_space *mapping;
-
-	if (file) {
-		mapping = file->f_mapping;
-		i_mmap_lock_write(mapping);
-		__vma_link_file(vma, mapping);
-		i_mmap_unlock_write(mapping);
-	}
-}
-
-static int vma_link(struct mm_struct *mm, struct vm_area_struct *vma)
-{
-	VMA_ITERATOR(vmi, mm, 0);
-
-	vma_iter_config(&vmi, vma->vm_start, vma->vm_end);
-	if (vma_iter_prealloc(&vmi, vma))
-		return -ENOMEM;
-
-	vma_start_write(vma);
-	vma_iter_store(&vmi, vma);
-	vma_link_file(vma);
-	mm->map_count++;
-	validate_mm(mm);
-	return 0;
-}
-
-/*
- * init_multi_vma_prep() - Initializer for struct vma_prepare
- * @vp: The vma_prepare struct
- * @vma: The vma that will be altered once locked
- * @next: The next vma if it is to be adjusted
- * @remove: The first vma to be removed
- * @remove2: The second vma to be removed
- */
-static inline void init_multi_vma_prep(struct vma_prepare *vp,
-		struct vm_area_struct *vma, struct vm_area_struct *next,
-		struct vm_area_struct *remove, struct vm_area_struct *remove2)
-{
-	memset(vp, 0, sizeof(struct vma_prepare));
-	vp->vma = vma;
-	vp->anon_vma = vma->anon_vma;
-	vp->remove = remove;
-	vp->remove2 = remove2;
-	vp->adj_next = next;
-	if (!vp->anon_vma && next)
-		vp->anon_vma = next->anon_vma;
-
-	vp->file = vma->vm_file;
-	if (vp->file)
-		vp->mapping = vma->vm_file->f_mapping;
-
-}
-
-/*
- * init_vma_prep() - Initializer wrapper for vma_prepare struct
- * @vp: The vma_prepare struct
- * @vma: The vma that will be altered once locked
- */
-static inline void init_vma_prep(struct vma_prepare *vp,
-				 struct vm_area_struct *vma)
-{
-	init_multi_vma_prep(vp, vma, NULL, NULL, NULL);
-}
-
-
-/*
- * vma_prepare() - Helper function for handling locking VMAs prior to altering
- * @vp: The initialized vma_prepare struct
- */
-static inline void vma_prepare(struct vma_prepare *vp)
-{
-	if (vp->file) {
-		uprobe_munmap(vp->vma, vp->vma->vm_start, vp->vma->vm_end);
-
-		if (vp->adj_next)
-			uprobe_munmap(vp->adj_next, vp->adj_next->vm_start,
-				      vp->adj_next->vm_end);
-
-		i_mmap_lock_write(vp->mapping);
-		if (vp->insert && vp->insert->vm_file) {
-			/*
-			 * Put into interval tree now, so instantiated pages
-			 * are visible to arm/parisc __flush_dcache_page
-			 * throughout; but we cannot insert into address
-			 * space until vma start or end is updated.
-			 */
-			__vma_link_file(vp->insert,
-					vp->insert->vm_file->f_mapping);
-		}
-	}
-
-	if (vp->anon_vma) {
-		anon_vma_lock_write(vp->anon_vma);
-		anon_vma_interval_tree_pre_update_vma(vp->vma);
-		if (vp->adj_next)
-			anon_vma_interval_tree_pre_update_vma(vp->adj_next);
-	}
-
-	if (vp->file) {
-		flush_dcache_mmap_lock(vp->mapping);
-		vma_interval_tree_remove(vp->vma, &vp->mapping->i_mmap);
-		if (vp->adj_next)
-			vma_interval_tree_remove(vp->adj_next,
-						 &vp->mapping->i_mmap);
-	}
-
-}
-
-/*
- * vma_complete- Helper function for handling the unlocking after altering VMAs,
- * or for inserting a VMA.
- *
- * @vp: The vma_prepare struct
- * @vmi: The vma iterator
- * @mm: The mm_struct
- */
-static inline void vma_complete(struct vma_prepare *vp,
-				struct vma_iterator *vmi, struct mm_struct *mm)
-{
-	if (vp->file) {
-		if (vp->adj_next)
-			vma_interval_tree_insert(vp->adj_next,
-						 &vp->mapping->i_mmap);
-		vma_interval_tree_insert(vp->vma, &vp->mapping->i_mmap);
-		flush_dcache_mmap_unlock(vp->mapping);
-	}
-
-	if (vp->remove && vp->file) {
-		__remove_shared_vm_struct(vp->remove, vp->mapping);
-		if (vp->remove2)
-			__remove_shared_vm_struct(vp->remove2, vp->mapping);
-	} else if (vp->insert) {
-		/*
-		 * split_vma has split insert from vma, and needs
-		 * us to insert it before dropping the locks
-		 * (it may either follow vma or precede it).
-		 */
-		vma_iter_store(vmi, vp->insert);
-		mm->map_count++;
-	}
-
-	if (vp->anon_vma) {
-		anon_vma_interval_tree_post_update_vma(vp->vma);
-		if (vp->adj_next)
-			anon_vma_interval_tree_post_update_vma(vp->adj_next);
-		anon_vma_unlock_write(vp->anon_vma);
-	}
-
-	if (vp->file) {
-		i_mmap_unlock_write(vp->mapping);
-		uprobe_mmap(vp->vma);
-
-		if (vp->adj_next)
-			uprobe_mmap(vp->adj_next);
-	}
-
-	if (vp->remove) {
-again:
-		vma_mark_detached(vp->remove, true);
-		if (vp->file) {
-			uprobe_munmap(vp->remove, vp->remove->vm_start,
-				      vp->remove->vm_end);
-			fput(vp->file);
-		}
-		if (vp->remove->anon_vma)
-			anon_vma_merge(vp->vma, vp->remove);
-		mm->map_count--;
-		mpol_put(vma_policy(vp->remove));
-		if (!vp->remove2)
-			WARN_ON_ONCE(vp->vma->vm_end < vp->remove->vm_end);
-		vm_area_free(vp->remove);
-
-		/*
-		 * In mprotect's case 6 (see comments on vma_merge),
-		 * we are removing both mid and next vmas
-		 */
-		if (vp->remove2) {
-			vp->remove = vp->remove2;
-			vp->remove2 = NULL;
-			goto again;
-		}
-	}
-	if (vp->insert && vp->file)
-		uprobe_mmap(vp->insert);
-	validate_mm(mm);
-}
-
-/*
- * dup_anon_vma() - Helper function to duplicate anon_vma
- * @dst: The destination VMA
- * @src: The source VMA
- * @dup: Pointer to the destination VMA when successful.
- *
- * Returns: 0 on success.
- */
-static inline int dup_anon_vma(struct vm_area_struct *dst,
-		struct vm_area_struct *src, struct vm_area_struct **dup)
-{
-	/*
-	 * Easily overlooked: when mprotect shifts the boundary, make sure the
-	 * expanding vma has anon_vma set if the shrinking vma had, to cover any
-	 * anon pages imported.
-	 */
-	if (src->anon_vma && !dst->anon_vma) {
-		int ret;
-
-		vma_assert_write_locked(dst);
-		dst->anon_vma = src->anon_vma;
-		ret = anon_vma_clone(dst, src);
-		if (ret)
-			return ret;
-
-		*dup = dst;
-	}
-
-	return 0;
-}
-
-/*
- * vma_expand - Expand an existing VMA
- *
- * @vmi: The vma iterator
- * @vma: The vma to expand
- * @start: The start of the vma
- * @end: The exclusive end of the vma
- * @pgoff: The page offset of vma
- * @next: The current of next vma.
- *
- * Expand @vma to @start and @end.  Can expand off the start and end.  Will
- * expand over @next if it's different from @vma and @end == @next->vm_end.
- * Checking if the @vma can expand and merge with @next needs to be handled by
- * the caller.
- *
- * Returns: 0 on success
- */
-int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma,
-	       unsigned long start, unsigned long end, pgoff_t pgoff,
-	       struct vm_area_struct *next)
-{
-	struct vm_area_struct *anon_dup = NULL;
-	bool remove_next = false;
-	struct vma_prepare vp;
-
-	vma_start_write(vma);
-	if (next && (vma != next) && (end == next->vm_end)) {
-		int ret;
-
-		remove_next = true;
-		vma_start_write(next);
-		ret = dup_anon_vma(vma, next, &anon_dup);
-		if (ret)
-			return ret;
-	}
-
-	init_multi_vma_prep(&vp, vma, NULL, remove_next ? next : NULL, NULL);
-	/* Not merging but overwriting any part of next is not handled. */
-	VM_WARN_ON(next && !vp.remove &&
-		  next != vma && end > next->vm_start);
-	/* Only handles expanding */
-	VM_WARN_ON(vma->vm_start < start || vma->vm_end > end);
-
-	/* Note: vma iterator must be pointing to 'start' */
-	vma_iter_config(vmi, start, end);
-	if (vma_iter_prealloc(vmi, vma))
-		goto nomem;
-
-	vma_prepare(&vp);
-	vma_adjust_trans_huge(vma, start, end, 0);
-	vma_set_range(vma, start, end, pgoff);
-	vma_iter_store(vmi, vma);
-
-	vma_complete(&vp, vmi, vma->vm_mm);
-	return 0;
-
-nomem:
-	if (anon_dup)
-		unlink_anon_vmas(anon_dup);
-	return -ENOMEM;
-}
-
-/*
- * vma_shrink() - Reduce an existing VMAs memory area
- * @vmi: The vma iterator
- * @vma: The VMA to modify
- * @start: The new start
- * @end: The new end
- *
- * Returns: 0 on success, -ENOMEM otherwise
- */
-int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma,
-	       unsigned long start, unsigned long end, pgoff_t pgoff)
-{
-	struct vma_prepare vp;
-
-	WARN_ON((vma->vm_start != start) && (vma->vm_end != end));
-
-	if (vma->vm_start < start)
-		vma_iter_config(vmi, vma->vm_start, start);
-	else
-		vma_iter_config(vmi, end, vma->vm_end);
-
-	if (vma_iter_prealloc(vmi, NULL))
-		return -ENOMEM;
-
-	vma_start_write(vma);
-
-	init_vma_prep(&vp, vma);
-	vma_prepare(&vp);
-	vma_adjust_trans_huge(vma, start, end, 0);
-
-	vma_iter_clear(vmi);
-	vma_set_range(vma, start, end, pgoff);
-	vma_complete(&vp, vmi, vma->vm_mm);
-	return 0;
-}
-
-/*
- * If the vma has a ->close operation then the driver probably needs to release
- * per-vma resources, so we don't attempt to merge those if the caller indicates
- * the current vma may be removed as part of the merge.
- */
-static inline bool is_mergeable_vma(struct vm_area_struct *vma,
-		struct file *file, unsigned long vm_flags,
-		struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
-		struct anon_vma_name *anon_name, bool may_remove_vma)
-{
-	/*
-	 * VM_SOFTDIRTY should not prevent from VMA merging, if we
-	 * match the flags but dirty bit -- the caller should mark
-	 * merged VMA as dirty. If dirty bit won't be excluded from
-	 * comparison, we increase pressure on the memory system forcing
-	 * the kernel to generate new VMAs when old one could be
-	 * extended instead.
-	 */
-	if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
-		return false;
-	if (vma->vm_file != file)
-		return false;
-	if (may_remove_vma && vma->vm_ops && vma->vm_ops->close)
-		return false;
-	if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx))
-		return false;
-	if (!anon_vma_name_eq(anon_vma_name(vma), anon_name))
-		return false;
-	return true;
-}
-
-static inline bool is_mergeable_anon_vma(struct anon_vma *anon_vma1,
-		 struct anon_vma *anon_vma2, struct vm_area_struct *vma)
-{
-	/*
-	 * The list_is_singular() test is to avoid merging VMA cloned from
-	 * parents. This can improve scalability caused by anon_vma lock.
-	 */
-	if ((!anon_vma1 || !anon_vma2) && (!vma ||
-		list_is_singular(&vma->anon_vma_chain)))
-		return true;
-	return anon_vma1 == anon_vma2;
-}
-
-/*
- * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
- * in front of (at a lower virtual address and file offset than) the vma.
- *
- * We cannot merge two vmas if they have differently assigned (non-NULL)
- * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
- *
- * We don't check here for the merged mmap wrapping around the end of pagecache
- * indices (16TB on ia32) because do_mmap() does not permit mmap's which
- * wrap, nor mmaps which cover the final page at index -1UL.
- *
- * We assume the vma may be removed as part of the merge.
- */
-static bool
-can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
-		struct anon_vma *anon_vma, struct file *file,
-		pgoff_t vm_pgoff, struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
-		struct anon_vma_name *anon_name)
-{
-	if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name, true) &&
-	    is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
-		if (vma->vm_pgoff == vm_pgoff)
-			return true;
-	}
-	return false;
-}
-
-/*
- * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
- * beyond (at a higher virtual address and file offset than) the vma.
- *
- * We cannot merge two vmas if they have differently assigned (non-NULL)
- * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
- *
- * We assume that vma is not removed as part of the merge.
- */
-static bool
-can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
-		struct anon_vma *anon_vma, struct file *file,
-		pgoff_t vm_pgoff, struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
-		struct anon_vma_name *anon_name)
-{
-	if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name, false) &&
-	    is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
-		pgoff_t vm_pglen;
-		vm_pglen = vma_pages(vma);
-		if (vma->vm_pgoff + vm_pglen == vm_pgoff)
-			return true;
-	}
-	return false;
-}
-
-/*
- * Given a mapping request (addr,end,vm_flags,file,pgoff,anon_name),
- * figure out whether that can be merged with its predecessor or its
- * successor.  Or both (it neatly fills a hole).
- *
- * In most cases - when called for mmap, brk or mremap - [addr,end) is
- * certain not to be mapped by the time vma_merge is called; but when
- * called for mprotect, it is certain to be already mapped (either at
- * an offset within prev, or at the start of next), and the flags of
- * this area are about to be changed to vm_flags - and the no-change
- * case has already been eliminated.
- *
- * The following mprotect cases have to be considered, where **** is
- * the area passed down from mprotect_fixup, never extending beyond one
- * vma, PPPP is the previous vma, CCCC is a concurrent vma that starts
- * at the same address as **** and is of the same or larger span, and
- * NNNN the next vma after ****:
- *
- *     ****             ****                   ****
- *    PPPPPPNNNNNN    PPPPPPNNNNNN       PPPPPPCCCCCC
- *    cannot merge    might become       might become
- *                    PPNNNNNNNNNN       PPPPPPPPPPCC
- *    mmap, brk or    case 4 below       case 5 below
- *    mremap move:
- *                        ****               ****
- *                    PPPP    NNNN       PPPPCCCCNNNN
- *                    might become       might become
- *                    PPPPPPPPPPPP 1 or  PPPPPPPPPPPP 6 or
- *                    PPPPPPPPNNNN 2 or  PPPPPPPPNNNN 7 or
- *                    PPPPNNNNNNNN 3     PPPPNNNNNNNN 8
- *
- * It is important for case 8 that the vma CCCC overlapping the
- * region **** is never going to extended over NNNN. Instead NNNN must
- * be extended in region **** and CCCC must be removed. This way in
- * all cases where vma_merge succeeds, the moment vma_merge drops the
- * rmap_locks, the properties of the merged vma will be already
- * correct for the whole merged range. Some of those properties like
- * vm_page_prot/vm_flags may be accessed by rmap_walks and they must
- * be correct for the whole merged range immediately after the
- * rmap_locks are released. Otherwise if NNNN would be removed and
- * CCCC would be extended over the NNNN range, remove_migration_ptes
- * or other rmap walkers (if working on addresses beyond the "end"
- * parameter) may establish ptes with the wrong permissions of CCCC
- * instead of the right permissions of NNNN.
- *
- * In the code below:
- * PPPP is represented by *prev
- * CCCC is represented by *curr or not represented at all (NULL)
- * NNNN is represented by *next or not represented at all (NULL)
- * **** is not represented - it will be merged and the vma containing the
- *      area is returned, or the function will return NULL
- */
-static struct vm_area_struct
-*vma_merge(struct vma_iterator *vmi, struct vm_area_struct *prev,
-	   struct vm_area_struct *src, unsigned long addr, unsigned long end,
-	   unsigned long vm_flags, pgoff_t pgoff, struct mempolicy *policy,
-	   struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
-	   struct anon_vma_name *anon_name)
-{
-	struct mm_struct *mm = src->vm_mm;
-	struct anon_vma *anon_vma = src->anon_vma;
-	struct file *file = src->vm_file;
-	struct vm_area_struct *curr, *next, *res;
-	struct vm_area_struct *vma, *adjust, *remove, *remove2;
-	struct vm_area_struct *anon_dup = NULL;
-	struct vma_prepare vp;
-	pgoff_t vma_pgoff;
-	int err = 0;
-	bool merge_prev = false;
-	bool merge_next = false;
-	bool vma_expanded = false;
-	unsigned long vma_start = addr;
-	unsigned long vma_end = end;
-	pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
-	long adj_start = 0;
-
-	/*
-	 * We later require that vma->vm_flags == vm_flags,
-	 * so this tests vma->vm_flags & VM_SPECIAL, too.
-	 */
-	if (vm_flags & VM_SPECIAL)
-		return NULL;
-
-	/* Does the input range span an existing VMA? (cases 5 - 8) */
-	curr = find_vma_intersection(mm, prev ? prev->vm_end : 0, end);
-
-	if (!curr ||			/* cases 1 - 4 */
-	    end == curr->vm_end)	/* cases 6 - 8, adjacent VMA */
-		next = vma_lookup(mm, end);
-	else
-		next = NULL;		/* case 5 */
-
-	if (prev) {
-		vma_start = prev->vm_start;
-		vma_pgoff = prev->vm_pgoff;
-
-		/* Can we merge the predecessor? */
-		if (addr == prev->vm_end && mpol_equal(vma_policy(prev), policy)
-		    && can_vma_merge_after(prev, vm_flags, anon_vma, file,
-					   pgoff, vm_userfaultfd_ctx, anon_name)) {
-			merge_prev = true;
-			vma_prev(vmi);
-		}
-	}
-
-	/* Can we merge the successor? */
-	if (next && mpol_equal(policy, vma_policy(next)) &&
-	    can_vma_merge_before(next, vm_flags, anon_vma, file, pgoff+pglen,
-				 vm_userfaultfd_ctx, anon_name)) {
-		merge_next = true;
-	}
-
-	/* Verify some invariant that must be enforced by the caller. */
-	VM_WARN_ON(prev && addr <= prev->vm_start);
-	VM_WARN_ON(curr && (addr != curr->vm_start || end > curr->vm_end));
-	VM_WARN_ON(addr >= end);
-
-	if (!merge_prev && !merge_next)
-		return NULL; /* Not mergeable. */
-
-	if (merge_prev)
-		vma_start_write(prev);
-
-	res = vma = prev;
-	remove = remove2 = adjust = NULL;
-
-	/* Can we merge both the predecessor and the successor? */
-	if (merge_prev && merge_next &&
-	    is_mergeable_anon_vma(prev->anon_vma, next->anon_vma, NULL)) {
-		vma_start_write(next);
-		remove = next;				/* case 1 */
-		vma_end = next->vm_end;
-		err = dup_anon_vma(prev, next, &anon_dup);
-		if (curr) {				/* case 6 */
-			vma_start_write(curr);
-			remove = curr;
-			remove2 = next;
-			/*
-			 * Note that the dup_anon_vma below cannot overwrite err
-			 * since the first caller would do nothing unless next
-			 * has an anon_vma.
-			 */
-			if (!next->anon_vma)
-				err = dup_anon_vma(prev, curr, &anon_dup);
-		}
-	} else if (merge_prev) {			/* case 2 */
-		if (curr) {
-			vma_start_write(curr);
-			if (end == curr->vm_end) {	/* case 7 */
-				/*
-				 * can_vma_merge_after() assumed we would not be
-				 * removing prev vma, so it skipped the check
-				 * for vm_ops->close, but we are removing curr
-				 */
-				if (curr->vm_ops && curr->vm_ops->close)
-					err = -EINVAL;
-				remove = curr;
-			} else {			/* case 5 */
-				adjust = curr;
-				adj_start = (end - curr->vm_start);
-			}
-			if (!err)
-				err = dup_anon_vma(prev, curr, &anon_dup);
-		}
-	} else { /* merge_next */
-		vma_start_write(next);
-		res = next;
-		if (prev && addr < prev->vm_end) {	/* case 4 */
-			vma_start_write(prev);
-			vma_end = addr;
-			adjust = next;
-			adj_start = -(prev->vm_end - addr);
-			err = dup_anon_vma(next, prev, &anon_dup);
-		} else {
-			/*
-			 * Note that cases 3 and 8 are the ONLY ones where prev
-			 * is permitted to be (but is not necessarily) NULL.
-			 */
-			vma = next;			/* case 3 */
-			vma_start = addr;
-			vma_end = next->vm_end;
-			vma_pgoff = next->vm_pgoff - pglen;
-			if (curr) {			/* case 8 */
-				vma_pgoff = curr->vm_pgoff;
-				vma_start_write(curr);
-				remove = curr;
-				err = dup_anon_vma(next, curr, &anon_dup);
-			}
-		}
-	}
-
-	/* Error in anon_vma clone. */
-	if (err)
-		goto anon_vma_fail;
-
-	if (vma_start < vma->vm_start || vma_end > vma->vm_end)
-		vma_expanded = true;
-
-	if (vma_expanded) {
-		vma_iter_config(vmi, vma_start, vma_end);
-	} else {
-		vma_iter_config(vmi, adjust->vm_start + adj_start,
-				adjust->vm_end);
-	}
-
-	if (vma_iter_prealloc(vmi, vma))
-		goto prealloc_fail;
-
-	init_multi_vma_prep(&vp, vma, adjust, remove, remove2);
-	VM_WARN_ON(vp.anon_vma && adjust && adjust->anon_vma &&
-		   vp.anon_vma != adjust->anon_vma);
-
-	vma_prepare(&vp);
-	vma_adjust_trans_huge(vma, vma_start, vma_end, adj_start);
-	vma_set_range(vma, vma_start, vma_end, vma_pgoff);
-
-	if (vma_expanded)
-		vma_iter_store(vmi, vma);
-
-	if (adj_start) {
-		adjust->vm_start += adj_start;
-		adjust->vm_pgoff += adj_start >> PAGE_SHIFT;
-		if (adj_start < 0) {
-			WARN_ON(vma_expanded);
-			vma_iter_store(vmi, next);
-		}
-	}
-
-	vma_complete(&vp, vmi, mm);
-	khugepaged_enter_vma(res, vm_flags);
-	return res;
-
-prealloc_fail:
-	if (anon_dup)
-		unlink_anon_vmas(anon_dup);
-
-anon_vma_fail:
-	vma_iter_set(vmi, addr);
-	vma_iter_load(vmi);
-	return NULL;
-}
-
-/*
- * Rough compatibility check to quickly see if it's even worth looking
- * at sharing an anon_vma.
- *
- * They need to have the same vm_file, and the flags can only differ
- * in things that mprotect may change.
- *
- * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
- * we can merge the two vma's. For example, we refuse to merge a vma if
- * there is a vm_ops->close() function, because that indicates that the
- * driver is doing some kind of reference counting. But that doesn't
- * really matter for the anon_vma sharing case.
- */
-static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
-{
-	return a->vm_end == b->vm_start &&
-		mpol_equal(vma_policy(a), vma_policy(b)) &&
-		a->vm_file == b->vm_file &&
-		!((a->vm_flags ^ b->vm_flags) & ~(VM_ACCESS_FLAGS | VM_SOFTDIRTY)) &&
-		b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
-}
-
-/*
- * Do some basic sanity checking to see if we can re-use the anon_vma
- * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
- * the same as 'old', the other will be the new one that is trying
- * to share the anon_vma.
- *
- * NOTE! This runs with mmap_lock held for reading, so it is possible that
- * the anon_vma of 'old' is concurrently in the process of being set up
- * by another page fault trying to merge _that_. But that's ok: if it
- * is being set up, that automatically means that it will be a singleton
- * acceptable for merging, so we can do all of this optimistically. But
- * we do that READ_ONCE() to make sure that we never re-load the pointer.
- *
- * IOW: that the "list_is_singular()" test on the anon_vma_chain only
- * matters for the 'stable anon_vma' case (ie the thing we want to avoid
- * is to return an anon_vma that is "complex" due to having gone through
- * a fork).
- *
- * We also make sure that the two vma's are compatible (adjacent,
- * and with the same memory policies). That's all stable, even with just
- * a read lock on the mmap_lock.
- */
-static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
-{
-	if (anon_vma_compatible(a, b)) {
-		struct anon_vma *anon_vma = READ_ONCE(old->anon_vma);
-
-		if (anon_vma && list_is_singular(&old->anon_vma_chain))
-			return anon_vma;
-	}
-	return NULL;
-}
-
-/*
- * find_mergeable_anon_vma is used by anon_vma_prepare, to check
- * neighbouring vmas for a suitable anon_vma, before it goes off
- * to allocate a new anon_vma.  It checks because a repetitive
- * sequence of mprotects and faults may otherwise lead to distinct
- * anon_vmas being allocated, preventing vma merge in subsequent
- * mprotect.
- */
-struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
-{
-	struct anon_vma *anon_vma = NULL;
-	struct vm_area_struct *prev, *next;
-	VMA_ITERATOR(vmi, vma->vm_mm, vma->vm_end);
-
-	/* Try next first. */
-	next = vma_iter_load(&vmi);
-	if (next) {
-		anon_vma = reusable_anon_vma(next, vma, next);
-		if (anon_vma)
-			return anon_vma;
-	}
-
-	prev = vma_prev(&vmi);
-	VM_BUG_ON_VMA(prev != vma, vma);
-	prev = vma_prev(&vmi);
-	/* Try prev next. */
-	if (prev)
-		anon_vma = reusable_anon_vma(prev, prev, vma);
-
-	/*
-	 * We might reach here with anon_vma == NULL if we can't find
-	 * any reusable anon_vma.
-	 * There's no absolute need to look only at touching neighbours:
-	 * we could search further afield for "compatible" anon_vmas.
-	 * But it would probably just be a waste of time searching,
-	 * or lead to too many vmas hanging off the same anon_vma.
-	 * We're trying to allow mprotect remerging later on,
-	 * not trying to minimize memory used for anon_vmas.
-	 */
-	return anon_vma;
-}
-
 /*
  * If a hint addr is less than mmap_min_addr change hint to be as
  * low as possible but still greater than mmap_min_addr
@@ -1549,85 +577,6 @@ SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
 }
 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
 
-static bool vm_ops_needs_writenotify(const struct vm_operations_struct *vm_ops)
-{
-	return vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite);
-}
-
-static bool vma_is_shared_writable(struct vm_area_struct *vma)
-{
-	return (vma->vm_flags & (VM_WRITE | VM_SHARED)) ==
-		(VM_WRITE | VM_SHARED);
-}
-
-static bool vma_fs_can_writeback(struct vm_area_struct *vma)
-{
-	/* No managed pages to writeback. */
-	if (vma->vm_flags & VM_PFNMAP)
-		return false;
-
-	return vma->vm_file && vma->vm_file->f_mapping &&
-		mapping_can_writeback(vma->vm_file->f_mapping);
-}
-
-/*
- * Does this VMA require the underlying folios to have their dirty state
- * tracked?
- */
-bool vma_needs_dirty_tracking(struct vm_area_struct *vma)
-{
-	/* Only shared, writable VMAs require dirty tracking. */
-	if (!vma_is_shared_writable(vma))
-		return false;
-
-	/* Does the filesystem need to be notified? */
-	if (vm_ops_needs_writenotify(vma->vm_ops))
-		return true;
-
-	/*
-	 * Even if the filesystem doesn't indicate a need for writenotify, if it
-	 * can writeback, dirty tracking is still required.
-	 */
-	return vma_fs_can_writeback(vma);
-}
-
-/*
- * Some shared mappings will want the pages marked read-only
- * to track write events. If so, we'll downgrade vm_page_prot
- * to the private version (using protection_map[] without the
- * VM_SHARED bit).
- */
-bool vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot)
-{
-	/* If it was private or non-writable, the write bit is already clear */
-	if (!vma_is_shared_writable(vma))
-		return false;
-
-	/* The backer wishes to know when pages are first written to? */
-	if (vm_ops_needs_writenotify(vma->vm_ops))
-		return true;
-
-	/* The open routine did something to the protections that pgprot_modify
-	 * won't preserve? */
-	if (pgprot_val(vm_page_prot) !=
-	    pgprot_val(vm_pgprot_modify(vm_page_prot, vma->vm_flags)))
-		return false;
-
-	/*
-	 * Do we need to track softdirty? hugetlb does not support softdirty
-	 * tracking yet.
-	 */
-	if (vma_soft_dirty_enabled(vma) && !is_vm_hugetlb_page(vma))
-		return true;
-
-	/* Do we need write faults for uffd-wp tracking? */
-	if (userfaultfd_wp(vma))
-		return true;
-
-	/* Can the mapping track the dirty pages? */
-	return vma_fs_can_writeback(vma);
-}
-
 /*
  * We account for memory if it's a private writeable mapping,
  * not hugepages and VM_NORESERVE wasn't set.
@@ -1754,6 +703,18 @@ retry:
 }
 
 /*
+ * Determine if the allocation needs to ensure that there is no
+ * existing mapping within it's guard gaps, for use as start_gap.
+ */
+static inline unsigned long stack_guard_placement(vm_flags_t vm_flags)
+{
+	if (vm_flags & VM_SHADOW_STACK)
+		return PAGE_SIZE;
+
+	return 0;
+}
+
+/*
  * Search for an unmapped address range.
  *
  * We are looking for a range that:
@@ -1789,7 +750,7 @@ unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info)
 unsigned long
 generic_get_unmapped_area(struct file *filp, unsigned long addr,
 			  unsigned long len, unsigned long pgoff,
-			  unsigned long flags)
+			  unsigned long flags, vm_flags_t vm_flags)
 {
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma, *prev;
@@ -1814,6 +775,7 @@ generic_get_unmapped_area(struct file *filp, unsigned long addr,
 	info.length = len;
 	info.low_limit = mm->mmap_base;
 	info.high_limit = mmap_end;
+	info.start_gap = stack_guard_placement(vm_flags);
 	return vm_unmapped_area(&info);
 }
 
@@ -1821,9 +783,10 @@ generic_get_unmapped_area(struct file *filp, unsigned long addr,
 unsigned long
 arch_get_unmapped_area(struct file *filp, unsigned long addr,
 		       unsigned long len, unsigned long pgoff,
-		       unsigned long flags)
+		       unsigned long flags, vm_flags_t vm_flags)
 {
-	return generic_get_unmapped_area(filp, addr, len, pgoff, flags);
+	return generic_get_unmapped_area(filp, addr, len, pgoff, flags,
+					 vm_flags);
 }
 #endif
 
@@ -1834,7 +797,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 unsigned long
 generic_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
 				  unsigned long len, unsigned long pgoff,
-				  unsigned long flags)
+				  unsigned long flags, vm_flags_t vm_flags)
 {
 	struct vm_area_struct *vma, *prev;
 	struct mm_struct *mm = current->mm;
@@ -1862,6 +825,7 @@ generic_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
 	info.length = len;
 	info.low_limit = PAGE_SIZE;
 	info.high_limit = arch_get_mmap_base(addr, mm->mmap_base);
+	info.start_gap = stack_guard_placement(vm_flags);
 	addr = vm_unmapped_area(&info);
 
 	/*
@@ -1885,26 +849,10 @@ generic_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
 unsigned long
 arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
 			       unsigned long len, unsigned long pgoff,
-			       unsigned long flags)
+			       unsigned long flags, vm_flags_t vm_flags)
 {
-	return generic_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
-}
-#endif
-
-#ifndef HAVE_ARCH_UNMAPPED_AREA_VMFLAGS
-unsigned long
-arch_get_unmapped_area_vmflags(struct file *filp, unsigned long addr, unsigned long len,
-			       unsigned long pgoff, unsigned long flags, vm_flags_t vm_flags)
-{
-	return arch_get_unmapped_area(filp, addr, len, pgoff, flags);
-}
-
-unsigned long
-arch_get_unmapped_area_topdown_vmflags(struct file *filp, unsigned long addr,
-				       unsigned long len, unsigned long pgoff,
-				       unsigned long flags, vm_flags_t vm_flags)
-{
-	return arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
+	return generic_get_unmapped_area_topdown(filp, addr, len, pgoff, flags,
+						 vm_flags);
 }
 #endif
 
@@ -1914,9 +862,9 @@ unsigned long mm_get_unmapped_area_vmflags(struct mm_struct *mm, struct file *fi
 					   vm_flags_t vm_flags)
 {
 	if (test_bit(MMF_TOPDOWN, &mm->flags))
-		return arch_get_unmapped_area_topdown_vmflags(filp, addr, len, pgoff,
-							      flags, vm_flags);
-	return arch_get_unmapped_area_vmflags(filp, addr, len, pgoff, flags, vm_flags);
+		return arch_get_unmapped_area_topdown(filp, addr, len, pgoff,
+						      flags, vm_flags);
+	return arch_get_unmapped_area(filp, addr, len, pgoff, flags, vm_flags);
 }
 
 unsigned long
@@ -1978,8 +926,8 @@ mm_get_unmapped_area(struct mm_struct *mm, struct file *file,
 		     unsigned long pgoff, unsigned long flags)
 {
 	if (test_bit(MMF_TOPDOWN, &mm->flags))
-		return arch_get_unmapped_area_topdown(file, addr, len, pgoff, flags);
-	return arch_get_unmapped_area(file, addr, len, pgoff, flags);
+		return arch_get_unmapped_area_topdown(file, addr, len, pgoff, flags, 0);
+	return arch_get_unmapped_area(file, addr, len, pgoff, flags, 0);
 }
 EXPORT_SYMBOL(mm_get_unmapped_area);
 
@@ -2393,443 +1341,6 @@ success:
 	return vma;
 }
 
-/*
- * Ok - we have the memory areas we should free on a maple tree so release them,
- * and do the vma updates.
- *
- * Called with the mm semaphore held.
- */
-static inline void remove_mt(struct mm_struct *mm, struct ma_state *mas)
-{
-	unsigned long nr_accounted = 0;
-	struct vm_area_struct *vma;
-
-	/* Update high watermark before we lower total_vm */
-	update_hiwater_vm(mm);
-	mas_for_each(mas, vma, ULONG_MAX) {
-		long nrpages = vma_pages(vma);
-
-		if (vma->vm_flags & VM_ACCOUNT)
-			nr_accounted += nrpages;
-		vm_stat_account(mm, vma->vm_flags, -nrpages);
-		remove_vma(vma, false);
-	}
-	vm_unacct_memory(nr_accounted);
-}
-
-/*
- * Get rid of page table information in the indicated region.
- *
- * Called with the mm semaphore held.
- */
-static void unmap_region(struct mm_struct *mm, struct ma_state *mas,
-		struct vm_area_struct *vma, struct vm_area_struct *prev,
-		struct vm_area_struct *next, unsigned long start,
-		unsigned long end, unsigned long tree_end, bool mm_wr_locked)
-{
-	struct mmu_gather tlb;
-	unsigned long mt_start = mas->index;
-
-	lru_add_drain();
-	tlb_gather_mmu(&tlb, mm);
-	update_hiwater_rss(mm);
-	unmap_vmas(&tlb, mas, vma, start, end, tree_end, mm_wr_locked);
-	mas_set(mas, mt_start);
-	free_pgtables(&tlb, mas, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
-				 next ? next->vm_start : USER_PGTABLES_CEILING,
-				 mm_wr_locked);
-	tlb_finish_mmu(&tlb);
-}
-
-/*
- * __split_vma() bypasses sysctl_max_map_count checking.  We use this where it
- * has already been checked or doesn't make sense to fail.
- * VMA Iterator will point to the end VMA.
- */
-static int __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
-		       unsigned long addr, int new_below)
-{
-	struct vma_prepare vp;
-	struct vm_area_struct *new;
-	int err;
-
-	WARN_ON(vma->vm_start >= addr);
-	WARN_ON(vma->vm_end <= addr);
-
-	if (vma->vm_ops && vma->vm_ops->may_split) {
-		err = vma->vm_ops->may_split(vma, addr);
-		if (err)
-			return err;
-	}
-
-	new = vm_area_dup(vma);
-	if (!new)
-		return -ENOMEM;
-
-	if (new_below) {
-		new->vm_end = addr;
-	} else {
-		new->vm_start = addr;
-		new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
-	}
-
-	err = -ENOMEM;
-	vma_iter_config(vmi, new->vm_start, new->vm_end);
-	if (vma_iter_prealloc(vmi, new))
-		goto out_free_vma;
-
-	err = vma_dup_policy(vma, new);
-	if (err)
-		goto out_free_vmi;
-
-	err = anon_vma_clone(new, vma);
-	if (err)
-		goto out_free_mpol;
-
-	if (new->vm_file)
-		get_file(new->vm_file);
-
-	if (new->vm_ops && new->vm_ops->open)
-		new->vm_ops->open(new);
-
-	vma_start_write(vma);
-	vma_start_write(new);
-
-	init_vma_prep(&vp, vma);
-	vp.insert = new;
-	vma_prepare(&vp);
-	vma_adjust_trans_huge(vma, vma->vm_start, addr, 0);
-
-	if (new_below) {
-		vma->vm_start = addr;
-		vma->vm_pgoff += (addr - new->vm_start) >> PAGE_SHIFT;
-	} else {
-		vma->vm_end = addr;
-	}
-
-	/* vma_complete stores the new vma */
-	vma_complete(&vp, vmi, vma->vm_mm);
-
-	/* Success. */
-	if (new_below)
-		vma_next(vmi);
-	return 0;
-
-out_free_mpol:
-	mpol_put(vma_policy(new));
-out_free_vmi:
-	vma_iter_free(vmi);
-out_free_vma:
-	vm_area_free(new);
-	return err;
-}
-
-/*
- * Split a vma into two pieces at address 'addr', a new vma is allocated
- * either for the first part or the tail.
- */
-static int split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
-		     unsigned long addr, int new_below)
-{
-	if (vma->vm_mm->map_count >= sysctl_max_map_count)
-		return -ENOMEM;
-
-	return __split_vma(vmi, vma, addr, new_below);
-}
-
-/*
- * We are about to modify one or multiple of a VMA's flags, policy, userfaultfd
- * context and anonymous VMA name within the range [start, end).
- *
- * As a result, we might be able to merge the newly modified VMA range with an
- * adjacent VMA with identical properties.
- *
- * If no merge is possible and the range does not span the entirety of the VMA,
- * we then need to split the VMA to accommodate the change.
- *
- * The function returns either the merged VMA, the original VMA if a split was
- * required instead, or an error if the split failed.
- */
-struct vm_area_struct *vma_modify(struct vma_iterator *vmi,
-				  struct vm_area_struct *prev,
-				  struct vm_area_struct *vma,
-				  unsigned long start, unsigned long end,
-				  unsigned long vm_flags,
-				  struct mempolicy *policy,
-				  struct vm_userfaultfd_ctx uffd_ctx,
-				  struct anon_vma_name *anon_name)
-{
-	pgoff_t pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
-	struct vm_area_struct *merged;
-
-	merged = vma_merge(vmi, prev, vma, start, end, vm_flags,
-			   pgoff, policy, uffd_ctx, anon_name);
-	if (merged)
-		return merged;
-
-	if (vma->vm_start < start) {
-		int err = split_vma(vmi, vma, start, 1);
-
-		if (err)
-			return ERR_PTR(err);
-	}
-
-	if (vma->vm_end > end) {
-		int err = split_vma(vmi, vma, end, 0);
-
-		if (err)
-			return ERR_PTR(err);
-	}
-
-	return vma;
-}
-
-/*
- * Attempt to merge a newly mapped VMA with those adjacent to it. The caller
- * must ensure that [start, end) does not overlap any existing VMA.
- */
-static struct vm_area_struct
-*vma_merge_new_vma(struct vma_iterator *vmi, struct vm_area_struct *prev,
-		   struct vm_area_struct *vma, unsigned long start,
-		   unsigned long end, pgoff_t pgoff)
-{
-	return vma_merge(vmi, prev, vma, start, end, vma->vm_flags, pgoff,
-			 vma_policy(vma), vma->vm_userfaultfd_ctx, anon_vma_name(vma));
-}
-
-/*
- * Expand vma by delta bytes, potentially merging with an immediately adjacent
- * VMA with identical properties.
- */
-struct vm_area_struct *vma_merge_extend(struct vma_iterator *vmi,
-					struct vm_area_struct *vma,
-					unsigned long delta)
-{
-	pgoff_t pgoff = vma->vm_pgoff + vma_pages(vma);
-
-	/* vma is specified as prev, so case 1 or 2 will apply. */
-	return vma_merge(vmi, vma, vma, vma->vm_end, vma->vm_end + delta,
-			 vma->vm_flags, pgoff, vma_policy(vma),
-			 vma->vm_userfaultfd_ctx, anon_vma_name(vma));
-}
-
-/*
- * do_vmi_align_munmap() - munmap the aligned region from @start to @end.
- * @vmi: The vma iterator
- * @vma: The starting vm_area_struct
- * @mm: The mm_struct
- * @start: The aligned start address to munmap.
- * @end: The aligned end address to munmap.
- * @uf: The userfaultfd list_head
- * @unlock: Set to true to drop the mmap_lock.  unlocking only happens on
- * success.
- *
- * Return: 0 on success and drops the lock if so directed, error and leaves the
- * lock held otherwise.
- */
-static int
-do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
-		    struct mm_struct *mm, unsigned long start,
-		    unsigned long end, struct list_head *uf, bool unlock)
-{
-	struct vm_area_struct *prev, *next = NULL;
-	struct maple_tree mt_detach;
-	int count = 0;
-	int error = -ENOMEM;
-	unsigned long locked_vm = 0;
-	MA_STATE(mas_detach, &mt_detach, 0, 0);
-	mt_init_flags(&mt_detach, vmi->mas.tree->ma_flags & MT_FLAGS_LOCK_MASK);
-	mt_on_stack(mt_detach);
-
-	/*
-	 * If we need to split any vma, do it now to save pain later.
-	 *
-	 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
-	 * unmapped vm_area_struct will remain in use: so lower split_vma
-	 * places tmp vma above, and higher split_vma places tmp vma below.
-	 */
-
-	/* Does it split the first one? */
-	if (start > vma->vm_start) {
-
-		/*
-		 * Make sure that map_count on return from munmap() will
-		 * not exceed its limit; but let map_count go just above
-		 * its limit temporarily, to help free resources as expected.
-		 */
-		if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
-			goto map_count_exceeded;
-
-		error = __split_vma(vmi, vma, start, 1);
-		if (error)
-			goto start_split_failed;
-	}
-
-	/*
-	 * Detach a range of VMAs from the mm. Using next as a temp variable as
-	 * it is always overwritten.
-	 */
-	next = vma;
-	do {
-		/* Does it split the end? */
-		if (next->vm_end > end) {
-			error = __split_vma(vmi, next, end, 0);
-			if (error)
-				goto end_split_failed;
-		}
-		vma_start_write(next);
-		mas_set(&mas_detach, count);
-		error = mas_store_gfp(&mas_detach, next, GFP_KERNEL);
-		if (error)
-			goto munmap_gather_failed;
-		vma_mark_detached(next, true);
-		if (next->vm_flags & VM_LOCKED)
-			locked_vm += vma_pages(next);
-
-		count++;
-		if (unlikely(uf)) {
-			/*
-			 * If userfaultfd_unmap_prep returns an error the vmas
-			 * will remain split, but userland will get a
-			 * highly unexpected error anyway. This is no
-			 * different than the case where the first of the two
-			 * __split_vma fails, but we don't undo the first
-			 * split, despite we could. This is unlikely enough
-			 * failure that it's not worth optimizing it for.
-			 */
-			error = userfaultfd_unmap_prep(next, start, end, uf);
-
-			if (error)
-				goto userfaultfd_error;
-		}
-#ifdef CONFIG_DEBUG_VM_MAPLE_TREE
-		BUG_ON(next->vm_start < start);
-		BUG_ON(next->vm_start > end);
-#endif
-	} for_each_vma_range(*vmi, next, end);
-
-#if defined(CONFIG_DEBUG_VM_MAPLE_TREE)
-	/* Make sure no VMAs are about to be lost. */
-	{
-		MA_STATE(test, &mt_detach, 0, 0);
-		struct vm_area_struct *vma_mas, *vma_test;
-		int test_count = 0;
-
-		vma_iter_set(vmi, start);
-		rcu_read_lock();
-		vma_test = mas_find(&test, count - 1);
-		for_each_vma_range(*vmi, vma_mas, end) {
-			BUG_ON(vma_mas != vma_test);
-			test_count++;
-			vma_test = mas_next(&test, count - 1);
-		}
-		rcu_read_unlock();
-		BUG_ON(count != test_count);
-	}
-#endif
-
-	while (vma_iter_addr(vmi) > start)
-		vma_iter_prev_range(vmi);
-
-	error = vma_iter_clear_gfp(vmi, start, end, GFP_KERNEL);
-	if (error)
-		goto clear_tree_failed;
-
-	/* Point of no return */
-	mm->locked_vm -= locked_vm;
-	mm->map_count -= count;
-	if (unlock)
-		mmap_write_downgrade(mm);
-
-	prev = vma_iter_prev_range(vmi);
-	next = vma_next(vmi);
-	if (next)
-		vma_iter_prev_range(vmi);
-
-	/*
-	 * We can free page tables without write-locking mmap_lock because VMAs
-	 * were isolated before we downgraded mmap_lock.
-	 */
-	mas_set(&mas_detach, 1);
-	unmap_region(mm, &mas_detach, vma, prev, next, start, end, count,
-		     !unlock);
-	/* Statistics and freeing VMAs */
-	mas_set(&mas_detach, 0);
-	remove_mt(mm, &mas_detach);
-	validate_mm(mm);
-	if (unlock)
-		mmap_read_unlock(mm);
-
-	__mt_destroy(&mt_detach);
-	return 0;
-
-clear_tree_failed:
-userfaultfd_error:
-munmap_gather_failed:
-end_split_failed:
-	mas_set(&mas_detach, 0);
-	mas_for_each(&mas_detach, next, end)
-		vma_mark_detached(next, false);
-
-	__mt_destroy(&mt_detach);
-start_split_failed:
-map_count_exceeded:
-	validate_mm(mm);
-	return error;
-}
-
-/*
- * do_vmi_munmap() - munmap a given range.
- * @vmi: The vma iterator
- * @mm: The mm_struct
- * @start: The start address to munmap
- * @len: The length of the range to munmap
- * @uf: The userfaultfd list_head
- * @unlock: set to true if the user wants to drop the mmap_lock on success
- *
- * This function takes a @mas that is either pointing to the previous VMA or set
- * to MA_START and sets it up to remove the mapping(s).  The @len will be
- * aligned and any arch_unmap work will be preformed.
- *
- * Return: 0 on success and drops the lock if so directed, error and leaves the
- * lock held otherwise.
- */
-int do_vmi_munmap(struct vma_iterator *vmi, struct mm_struct *mm,
-		  unsigned long start, size_t len, struct list_head *uf,
-		  bool unlock)
-{
-	unsigned long end;
-	struct vm_area_struct *vma;
-
-	if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start)
-		return -EINVAL;
-
-	end = start + PAGE_ALIGN(len);
-	if (end == start)
-		return -EINVAL;
-
-	/*
-	 * Check if memory is sealed before arch_unmap.
-	 * Prevent unmapping a sealed VMA.
-	 * can_modify_mm assumes we have acquired the lock on MM.
-	 */
-	if (unlikely(!can_modify_mm(mm, start, end)))
-		return -EPERM;
-
-	 /* arch_unmap() might do unmaps itself.  */
-	arch_unmap(mm, start, end);
-
-	/* Find the first overlapping VMA */
-	vma = vma_find(vmi, end);
-	if (!vma) {
-		if (unlock)
-			mmap_write_unlock(mm);
-		return 0;
-	}
-
-	return do_vmi_align_munmap(vmi, vma, mm, start, end, uf, unlock);
-}
-
 /* do_munmap() - Wrapper function for non-maple tree aware do_munmap() calls.
  * @mm: The mm_struct
  * @start: The start address to munmap
@@ -2852,100 +1363,67 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 {
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma = NULL;
-	struct vm_area_struct *next, *prev, *merge;
-	pgoff_t pglen = len >> PAGE_SHIFT;
+	pgoff_t pglen = PHYS_PFN(len);
+	struct vm_area_struct *merge;
 	unsigned long charged = 0;
+	struct vma_munmap_struct vms;
+	struct ma_state mas_detach;
+	struct maple_tree mt_detach;
 	unsigned long end = addr + len;
-	unsigned long merge_start = addr, merge_end = end;
 	bool writable_file_mapping = false;
-	pgoff_t vm_pgoff;
-	int error;
+	int error = -ENOMEM;
 	VMA_ITERATOR(vmi, mm, addr);
+	VMG_STATE(vmg, mm, &vmi, addr, end, vm_flags, pgoff);
 
-	/* Check against address space limit. */
-	if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) {
-		unsigned long nr_pages;
-
-		/*
-		 * MAP_FIXED may remove pages of mappings that intersects with
-		 * requested mapping. Account for the pages it would unmap.
-		 */
-		nr_pages = count_vma_pages_range(mm, addr, end);
+	vmg.file = file;
+	/* Find the first overlapping VMA */
+	vma = vma_find(&vmi, end);
+	init_vma_munmap(&vms, &vmi, vma, addr, end, uf, /* unlock = */ false);
+	if (vma) {
+		mt_init_flags(&mt_detach, vmi.mas.tree->ma_flags & MT_FLAGS_LOCK_MASK);
+		mt_on_stack(mt_detach);
+		mas_init(&mas_detach, &mt_detach, /* addr = */ 0);
+		/* Prepare to unmap any existing mapping in the area */
+		error = vms_gather_munmap_vmas(&vms, &mas_detach);
+		if (error)
+			goto gather_failed;
 
-		if (!may_expand_vm(mm, vm_flags,
-					(len >> PAGE_SHIFT) - nr_pages))
-			return -ENOMEM;
+		vmg.next = vms.next;
+		vmg.prev = vms.prev;
+		vma = NULL;
+	} else {
+		vmg.next = vma_iter_next_rewind(&vmi, &vmg.prev);
 	}
 
-	/* Unmap any existing mapping in the area */
-	error = do_vmi_munmap(&vmi, mm, addr, len, uf, false);
-	if (error == -EPERM)
-		return error;
-	else if (error)
-		return -ENOMEM;
+	/* Check against address space limit. */
+	if (!may_expand_vm(mm, vm_flags, pglen - vms.nr_pages))
+		goto abort_munmap;
 
 	/*
 	 * Private writable mapping: check memory availability
 	 */
 	if (accountable_mapping(file, vm_flags)) {
-		charged = len >> PAGE_SHIFT;
-		if (security_vm_enough_memory_mm(mm, charged))
-			return -ENOMEM;
-		vm_flags |= VM_ACCOUNT;
-	}
-
-	next = vma_next(&vmi);
-	prev = vma_prev(&vmi);
-	if (vm_flags & VM_SPECIAL) {
-		if (prev)
-			vma_iter_next_range(&vmi);
-		goto cannot_expand;
-	}
-
-	/* Attempt to expand an old mapping */
-	/* Check next */
-	if (next && next->vm_start == end && !vma_policy(next) &&
-	    can_vma_merge_before(next, vm_flags, NULL, file, pgoff+pglen,
-				 NULL_VM_UFFD_CTX, NULL)) {
-		merge_end = next->vm_end;
-		vma = next;
-		vm_pgoff = next->vm_pgoff - pglen;
-	}
+		charged = pglen;
+		charged -= vms.nr_accounted;
+		if (charged && security_vm_enough_memory_mm(mm, charged))
+			goto abort_munmap;
 
-	/* Check prev */
-	if (prev && prev->vm_end == addr && !vma_policy(prev) &&
-	    (vma ? can_vma_merge_after(prev, vm_flags, vma->anon_vma, file,
-				       pgoff, vma->vm_userfaultfd_ctx, NULL) :
-		   can_vma_merge_after(prev, vm_flags, NULL, file, pgoff,
-				       NULL_VM_UFFD_CTX, NULL))) {
-		merge_start = prev->vm_start;
-		vma = prev;
-		vm_pgoff = prev->vm_pgoff;
-	} else if (prev) {
-		vma_iter_next_range(&vmi);
+		vms.nr_accounted = 0;
+		vm_flags |= VM_ACCOUNT;
+		vmg.flags = vm_flags;
 	}
 
-	/* Actually expand, if possible */
-	if (vma &&
-	    !vma_expand(&vmi, vma, merge_start, merge_end, vm_pgoff, next)) {
-		khugepaged_enter_vma(vma, vm_flags);
+	vma = vma_merge_new_range(&vmg);
+	if (vma)
 		goto expanded;
-	}
-
-	if (vma == prev)
-		vma_iter_set(&vmi, addr);
-cannot_expand:
-
 	/*
 	 * Determine the object being mapped and call the appropriate
 	 * specific mapper. the address has already been validated, but
 	 * not unmapped, but the maps are removed from the list.
 	 */
 	vma = vm_area_alloc(mm);
-	if (!vma) {
-		error = -ENOMEM;
+	if (!vma)
 		goto unacct_error;
-	}
 
 	vma_iter_config(&vmi, addr, end);
 	vma_set_range(vma, addr, end, pgoff);
@@ -2954,6 +1432,11 @@ cannot_expand:
 
 	if (file) {
 		vma->vm_file = get_file(file);
+		/*
+		 * call_mmap() may map PTE, so ensure there are no existing PTEs
+		 * and call the vm_ops close function if one exists.
+		 */
+		vms_clean_up_area(&vms, &mas_detach);
 		error = call_mmap(file, vma);
 		if (error)
 			goto unmap_and_free_vma;
@@ -2979,10 +1462,11 @@ cannot_expand:
 		 * If vm_flags changed after call_mmap(), we should try merge
 		 * vma again as we may succeed this time.
 		 */
-		if (unlikely(vm_flags != vma->vm_flags && prev)) {
-			merge = vma_merge_new_vma(&vmi, prev, vma,
-						  vma->vm_start, vma->vm_end,
-						  vma->vm_pgoff);
+		if (unlikely(vm_flags != vma->vm_flags && vmg.prev)) {
+			vmg.flags = vma->vm_flags;
+			/* If this fails, state is reset ready for a reattempt. */
+			merge = vma_merge_new_range(&vmg);
+
 			if (merge) {
 				/*
 				 * ->mmap() can change vma->vm_file and fput
@@ -2998,6 +1482,7 @@ cannot_expand:
 				vm_flags = vma->vm_flags;
 				goto unmap_writable;
 			}
+			vma_iter_config(&vmi, addr, end);
 		}
 
 		vm_flags = vma->vm_flags;
@@ -3030,7 +1515,7 @@ cannot_expand:
 	vma_link_file(vma);
 
 	/*
-	 * vma_merge() calls khugepaged_enter_vma() either, the below
+	 * vma_merge_new_range() calls khugepaged_enter_vma() too, the below
 	 * call covers the non-merge case.
 	 */
 	khugepaged_enter_vma(vma, vma->vm_flags);
@@ -3044,14 +1529,17 @@ unmap_writable:
 expanded:
 	perf_event_mmap(vma);
 
-	vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT);
+	/* Unmap any existing mapping in the area */
+	vms_complete_munmap_vmas(&vms, &mas_detach);
+
+	vm_stat_account(mm, vm_flags, pglen);
 	if (vm_flags & VM_LOCKED) {
 		if ((vm_flags & VM_SPECIAL) || vma_is_dax(vma) ||
 					is_vm_hugetlb_page(vma) ||
 					vma == get_gate_vma(current->mm))
 			vm_flags_clear(vma, VM_LOCKED_MASK);
 		else
-			mm->locked_vm += (len >> PAGE_SHIFT);
+			mm->locked_vm += pglen;
 	}
 
 	if (file)
@@ -3072,7 +1560,7 @@ expanded:
 	return addr;
 
 close_and_free_vma:
-	if (file && vma->vm_ops && vma->vm_ops->close)
+	if (file && !vms.closed_vm_ops && vma->vm_ops && vma->vm_ops->close)
 		vma->vm_ops->close(vma);
 
 	if (file || vma->vm_file) {
@@ -3082,8 +1570,7 @@ unmap_and_free_vma:
 
 		vma_iter_set(&vmi, vma->vm_end);
 		/* Undo any partial mapping done by a device driver. */
-		unmap_region(mm, &vmi.mas, vma, prev, next, vma->vm_start,
-			     vma->vm_end, vma->vm_end, true);
+		unmap_region(&vmi.mas, vma, vmg.prev, vmg.next);
 	}
 	if (writable_file_mapping)
 		mapping_unmap_writable(file->f_mapping);
@@ -3092,6 +1579,10 @@ free_vma:
 unacct_error:
 	if (charged)
 		vm_unacct_memory(charged);
+
+abort_munmap:
+	vms_abort_munmap_vmas(&vms, &mas_detach);
+gather_failed:
 	validate_mm(mm);
 	return error;
 }
@@ -3211,39 +1702,6 @@ out:
 }
 
 /*
- * do_vma_munmap() - Unmap a full or partial vma.
- * @vmi: The vma iterator pointing at the vma
- * @vma: The first vma to be munmapped
- * @start: the start of the address to unmap
- * @end: The end of the address to unmap
- * @uf: The userfaultfd list_head
- * @unlock: Drop the lock on success
- *
- * unmaps a VMA mapping when the vma iterator is already in position.
- * Does not handle alignment.
- *
- * Return: 0 on success drops the lock of so directed, error on failure and will
- * still hold the lock.
- */
-int do_vma_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
-		unsigned long start, unsigned long end, struct list_head *uf,
-		bool unlock)
-{
-	struct mm_struct *mm = vma->vm_mm;
-
-	/*
-	 * Check if memory is sealed before arch_unmap.
-	 * Prevent unmapping a sealed VMA.
-	 * can_modify_mm assumes we have acquired the lock on MM.
-	 */
-	if (unlikely(!can_modify_mm(mm, start, end)))
-		return -EPERM;
-
-	arch_unmap(mm, start, end);
-	return do_vmi_align_munmap(vmi, vma, mm, start, end, uf, unlock);
-}
-
-/*
  * do_brk_flags() - Increase the brk vma if the flags match.
  * @vmi: The vma iterator
  * @addr: The start address
@@ -3259,7 +1717,6 @@ static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma,
 		unsigned long addr, unsigned long len, unsigned long flags)
 {
 	struct mm_struct *mm = current->mm;
-	struct vma_prepare vp;
 
 	/*
 	 * Check against address space limits by the changed size
@@ -3279,25 +1736,16 @@ static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma,
 	 * Expand the existing vma if possible; Note that singular lists do not
 	 * occur after forking, so the expand will only happen on new VMAs.
 	 */
-	if (vma && vma->vm_end == addr && !vma_policy(vma) &&
-	    can_vma_merge_after(vma, flags, NULL, NULL,
-				addr >> PAGE_SHIFT, NULL_VM_UFFD_CTX, NULL)) {
-		vma_iter_config(vmi, vma->vm_start, addr + len);
-		if (vma_iter_prealloc(vmi, vma))
-			goto unacct_fail;
+	if (vma && vma->vm_end == addr) {
+		VMG_STATE(vmg, mm, vmi, addr, addr + len, flags, PHYS_PFN(addr));
 
-		vma_start_write(vma);
-
-		init_vma_prep(&vp, vma);
-		vma_prepare(&vp);
-		vma_adjust_trans_huge(vma, vma->vm_start, addr + len, 0);
-		vma->vm_end = addr + len;
-		vm_flags_set(vma, VM_SOFTDIRTY);
-		vma_iter_store(vmi, vma);
+		vmg.prev = vma;
+		vma_iter_next_range(vmi);
 
-		vma_complete(&vp, vmi, mm);
-		khugepaged_enter_vma(vma, flags);
-		goto out;
+		if (vma_merge_new_range(&vmg))
+			goto out;
+		else if (vmg_nomem(&vmg))
+			goto unacct_fail;
 	}
 
 	if (vma)
@@ -3433,7 +1881,7 @@ void exit_mmap(struct mm_struct *mm)
 	do {
 		if (vma->vm_flags & VM_ACCOUNT)
 			nr_accounted += vma_pages(vma);
-		remove_vma(vma, true);
+		remove_vma(vma, /* unreachable = */ true, /* closed = */ false);
 		count++;
 		cond_resched();
 		vma = vma_next(&vmi);
@@ -3491,92 +1939,6 @@ int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
 }
 
 /*
- * Copy the vma structure to a new location in the same mm,
- * prior to moving page table entries, to effect an mremap move.
- */
-struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
-	unsigned long addr, unsigned long len, pgoff_t pgoff,
-	bool *need_rmap_locks)
-{
-	struct vm_area_struct *vma = *vmap;
-	unsigned long vma_start = vma->vm_start;
-	struct mm_struct *mm = vma->vm_mm;
-	struct vm_area_struct *new_vma, *prev;
-	bool faulted_in_anon_vma = true;
-	VMA_ITERATOR(vmi, mm, addr);
-
-	/*
-	 * If anonymous vma has not yet been faulted, update new pgoff
-	 * to match new location, to increase its chance of merging.
-	 */
-	if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) {
-		pgoff = addr >> PAGE_SHIFT;
-		faulted_in_anon_vma = false;
-	}
-
-	new_vma = find_vma_prev(mm, addr, &prev);
-	if (new_vma && new_vma->vm_start < addr + len)
-		return NULL;	/* should never get here */
-
-	new_vma = vma_merge_new_vma(&vmi, prev, vma, addr, addr + len, pgoff);
-	if (new_vma) {
-		/*
-		 * Source vma may have been merged into new_vma
-		 */
-		if (unlikely(vma_start >= new_vma->vm_start &&
-			     vma_start < new_vma->vm_end)) {
-			/*
-			 * The only way we can get a vma_merge with
-			 * self during an mremap is if the vma hasn't
-			 * been faulted in yet and we were allowed to
-			 * reset the dst vma->vm_pgoff to the
-			 * destination address of the mremap to allow
-			 * the merge to happen. mremap must change the
-			 * vm_pgoff linearity between src and dst vmas
-			 * (in turn preventing a vma_merge) to be
-			 * safe. It is only safe to keep the vm_pgoff
-			 * linear if there are no pages mapped yet.
-			 */
-			VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma);
-			*vmap = vma = new_vma;
-		}
-		*need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
-	} else {
-		new_vma = vm_area_dup(vma);
-		if (!new_vma)
-			goto out;
-		vma_set_range(new_vma, addr, addr + len, pgoff);
-		if (vma_dup_policy(vma, new_vma))
-			goto out_free_vma;
-		if (anon_vma_clone(new_vma, vma))
-			goto out_free_mempol;
-		if (new_vma->vm_file)
-			get_file(new_vma->vm_file);
-		if (new_vma->vm_ops && new_vma->vm_ops->open)
-			new_vma->vm_ops->open(new_vma);
-		if (vma_link(mm, new_vma))
-			goto out_vma_link;
-		*need_rmap_locks = false;
-	}
-	return new_vma;
-
-out_vma_link:
-	if (new_vma->vm_ops && new_vma->vm_ops->close)
-		new_vma->vm_ops->close(new_vma);
-
-	if (new_vma->vm_file)
-		fput(new_vma->vm_file);
-
-	unlink_anon_vmas(new_vma);
-out_free_mempol:
-	mpol_put(vma_policy(new_vma));
-out_free_vma:
-	vm_area_free(new_vma);
-out:
-	return NULL;
-}
-
-/*
  * Return true if the calling process may expand its vm space by the passed
  * number of pages
  */
@@ -3620,10 +1982,16 @@ void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages)
 static vm_fault_t special_mapping_fault(struct vm_fault *vmf);
 
 /*
+ * Close hook, called for unmap() and on the old vma for mremap().
+ *
  * Having a close hook prevents vma merging regardless of flags.
  */
 static void special_mapping_close(struct vm_area_struct *vma)
 {
+	const struct vm_special_mapping *sm = vma->vm_private_data;
+
+	if (sm->close)
+		sm->close(sm, vma);
 }
 
 static const char *special_mapping_name(struct vm_area_struct *vma)
@@ -3665,27 +2033,17 @@ static const struct vm_operations_struct special_mapping_vmops = {
 	.may_split = special_mapping_split,
 };
 
-static const struct vm_operations_struct legacy_special_mapping_vmops = {
-	.close = special_mapping_close,
-	.fault = special_mapping_fault,
-};
-
 static vm_fault_t special_mapping_fault(struct vm_fault *vmf)
 {
 	struct vm_area_struct *vma = vmf->vma;
 	pgoff_t pgoff;
 	struct page **pages;
+	struct vm_special_mapping *sm = vma->vm_private_data;
 
-	if (vma->vm_ops == &legacy_special_mapping_vmops) {
-		pages = vma->vm_private_data;
-	} else {
-		struct vm_special_mapping *sm = vma->vm_private_data;
-
-		if (sm->fault)
-			return sm->fault(sm, vmf->vma, vmf);
+	if (sm->fault)
+		return sm->fault(sm, vmf->vma, vmf);
 
-		pages = sm->pages;
-	}
+	pages = sm->pages;
 
 	for (pgoff = vmf->pgoff; pgoff && *pages; ++pages)
 		pgoff--;
@@ -3740,8 +2098,7 @@ bool vma_is_special_mapping(const struct vm_area_struct *vma,
 	const struct vm_special_mapping *sm)
 {
 	return vma->vm_private_data == sm &&
-		(vma->vm_ops == &special_mapping_vmops ||
-		 vma->vm_ops == &legacy_special_mapping_vmops);
+		vma->vm_ops == &special_mapping_vmops;
 }
 
 /*
@@ -3762,214 +2119,6 @@ struct vm_area_struct *_install_special_mapping(
 					&special_mapping_vmops);
 }
 
-int install_special_mapping(struct mm_struct *mm,
-			    unsigned long addr, unsigned long len,
-			    unsigned long vm_flags, struct page **pages)
-{
-	struct vm_area_struct *vma = __install_special_mapping(
-		mm, addr, len, vm_flags, (void *)pages,
-		&legacy_special_mapping_vmops);
-
-	return PTR_ERR_OR_ZERO(vma);
-}
-
-static DEFINE_MUTEX(mm_all_locks_mutex);
-
-static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
-{
-	if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) {
-		/*
-		 * The LSB of head.next can't change from under us
-		 * because we hold the mm_all_locks_mutex.
-		 */
-		down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_lock);
-		/*
-		 * We can safely modify head.next after taking the
-		 * anon_vma->root->rwsem. If some other vma in this mm shares
-		 * the same anon_vma we won't take it again.
-		 *
-		 * No need of atomic instructions here, head.next
-		 * can't change from under us thanks to the
-		 * anon_vma->root->rwsem.
-		 */
-		if (__test_and_set_bit(0, (unsigned long *)
-				       &anon_vma->root->rb_root.rb_root.rb_node))
-			BUG();
-	}
-}
-
-static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
-{
-	if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
-		/*
-		 * AS_MM_ALL_LOCKS can't change from under us because
-		 * we hold the mm_all_locks_mutex.
-		 *
-		 * Operations on ->flags have to be atomic because
-		 * even if AS_MM_ALL_LOCKS is stable thanks to the
-		 * mm_all_locks_mutex, there may be other cpus
-		 * changing other bitflags in parallel to us.
-		 */
-		if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
-			BUG();
-		down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_lock);
-	}
-}
-
-/*
- * This operation locks against the VM for all pte/vma/mm related
- * operations that could ever happen on a certain mm. This includes
- * vmtruncate, try_to_unmap, and all page faults.
- *
- * The caller must take the mmap_lock in write mode before calling
- * mm_take_all_locks(). The caller isn't allowed to release the
- * mmap_lock until mm_drop_all_locks() returns.
- *
- * mmap_lock in write mode is required in order to block all operations
- * that could modify pagetables and free pages without need of
- * altering the vma layout. It's also needed in write mode to avoid new
- * anon_vmas to be associated with existing vmas.
- *
- * A single task can't take more than one mm_take_all_locks() in a row
- * or it would deadlock.
- *
- * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
- * mapping->flags avoid to take the same lock twice, if more than one
- * vma in this mm is backed by the same anon_vma or address_space.
- *
- * We take locks in following order, accordingly to comment at beginning
- * of mm/rmap.c:
- *   - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for
- *     hugetlb mapping);
- *   - all vmas marked locked
- *   - all i_mmap_rwsem locks;
- *   - all anon_vma->rwseml
- *
- * We can take all locks within these types randomly because the VM code
- * doesn't nest them and we protected from parallel mm_take_all_locks() by
- * mm_all_locks_mutex.
- *
- * mm_take_all_locks() and mm_drop_all_locks are expensive operations
- * that may have to take thousand of locks.
- *
- * mm_take_all_locks() can fail if it's interrupted by signals.
- */
-int mm_take_all_locks(struct mm_struct *mm)
-{
-	struct vm_area_struct *vma;
-	struct anon_vma_chain *avc;
-	VMA_ITERATOR(vmi, mm, 0);
-
-	mmap_assert_write_locked(mm);
-
-	mutex_lock(&mm_all_locks_mutex);
-
-	/*
-	 * vma_start_write() does not have a complement in mm_drop_all_locks()
-	 * because vma_start_write() is always asymmetrical; it marks a VMA as
-	 * being written to until mmap_write_unlock() or mmap_write_downgrade()
-	 * is reached.
-	 */
-	for_each_vma(vmi, vma) {
-		if (signal_pending(current))
-			goto out_unlock;
-		vma_start_write(vma);
-	}
-
-	vma_iter_init(&vmi, mm, 0);
-	for_each_vma(vmi, vma) {
-		if (signal_pending(current))
-			goto out_unlock;
-		if (vma->vm_file && vma->vm_file->f_mapping &&
-				is_vm_hugetlb_page(vma))
-			vm_lock_mapping(mm, vma->vm_file->f_mapping);
-	}
-
-	vma_iter_init(&vmi, mm, 0);
-	for_each_vma(vmi, vma) {
-		if (signal_pending(current))
-			goto out_unlock;
-		if (vma->vm_file && vma->vm_file->f_mapping &&
-				!is_vm_hugetlb_page(vma))
-			vm_lock_mapping(mm, vma->vm_file->f_mapping);
-	}
-
-	vma_iter_init(&vmi, mm, 0);
-	for_each_vma(vmi, vma) {
-		if (signal_pending(current))
-			goto out_unlock;
-		if (vma->anon_vma)
-			list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
-				vm_lock_anon_vma(mm, avc->anon_vma);
-	}
-
-	return 0;
-
-out_unlock:
-	mm_drop_all_locks(mm);
-	return -EINTR;
-}
-
-static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
-{
-	if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) {
-		/*
-		 * The LSB of head.next can't change to 0 from under
-		 * us because we hold the mm_all_locks_mutex.
-		 *
-		 * We must however clear the bitflag before unlocking
-		 * the vma so the users using the anon_vma->rb_root will
-		 * never see our bitflag.
-		 *
-		 * No need of atomic instructions here, head.next
-		 * can't change from under us until we release the
-		 * anon_vma->root->rwsem.
-		 */
-		if (!__test_and_clear_bit(0, (unsigned long *)
-					  &anon_vma->root->rb_root.rb_root.rb_node))
-			BUG();
-		anon_vma_unlock_write(anon_vma);
-	}
-}
-
-static void vm_unlock_mapping(struct address_space *mapping)
-{
-	if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
-		/*
-		 * AS_MM_ALL_LOCKS can't change to 0 from under us
-		 * because we hold the mm_all_locks_mutex.
-		 */
-		i_mmap_unlock_write(mapping);
-		if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
-					&mapping->flags))
-			BUG();
-	}
-}
-
-/*
- * The mmap_lock cannot be released by the caller until
- * mm_drop_all_locks() returns.
- */
-void mm_drop_all_locks(struct mm_struct *mm)
-{
-	struct vm_area_struct *vma;
-	struct anon_vma_chain *avc;
-	VMA_ITERATOR(vmi, mm, 0);
-
-	mmap_assert_write_locked(mm);
-	BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
-
-	for_each_vma(vmi, vma) {
-		if (vma->anon_vma)
-			list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
-				vm_unlock_anon_vma(avc->anon_vma);
-		if (vma->vm_file && vma->vm_file->f_mapping)
-			vm_unlock_mapping(vma->vm_file->f_mapping);
-	}
-
-	mutex_unlock(&mm_all_locks_mutex);
-}
-
 /*
  * initialise the percpu counter for VM
  */
@@ -4088,3 +2237,86 @@ static int __meminit init_reserve_notifier(void)
 	return 0;
 }
 subsys_initcall(init_reserve_notifier);
+
+/*
+ * Relocate a VMA downwards by shift bytes. There cannot be any VMAs between
+ * this VMA and its relocated range, which will now reside at [vma->vm_start -
+ * shift, vma->vm_end - shift).
+ *
+ * This function is almost certainly NOT what you want for anything other than
+ * early executable temporary stack relocation.
+ */
+int relocate_vma_down(struct vm_area_struct *vma, unsigned long shift)
+{
+	/*
+	 * The process proceeds as follows:
+	 *
+	 * 1) Use shift to calculate the new vma endpoints.
+	 * 2) Extend vma to cover both the old and new ranges.  This ensures the
+	 *    arguments passed to subsequent functions are consistent.
+	 * 3) Move vma's page tables to the new range.
+	 * 4) Free up any cleared pgd range.
+	 * 5) Shrink the vma to cover only the new range.
+	 */
+
+	struct mm_struct *mm = vma->vm_mm;
+	unsigned long old_start = vma->vm_start;
+	unsigned long old_end = vma->vm_end;
+	unsigned long length = old_end - old_start;
+	unsigned long new_start = old_start - shift;
+	unsigned long new_end = old_end - shift;
+	VMA_ITERATOR(vmi, mm, new_start);
+	VMG_STATE(vmg, mm, &vmi, new_start, old_end, 0, vma->vm_pgoff);
+	struct vm_area_struct *next;
+	struct mmu_gather tlb;
+
+	BUG_ON(new_start > new_end);
+
+	/*
+	 * ensure there are no vmas between where we want to go
+	 * and where we are
+	 */
+	if (vma != vma_next(&vmi))
+		return -EFAULT;
+
+	vma_iter_prev_range(&vmi);
+	/*
+	 * cover the whole range: [new_start, old_end)
+	 */
+	vmg.vma = vma;
+	if (vma_expand(&vmg))
+		return -ENOMEM;
+
+	/*
+	 * move the page tables downwards, on failure we rely on
+	 * process cleanup to remove whatever mess we made.
+	 */
+	if (length != move_page_tables(vma, old_start,
+				       vma, new_start, length, false, true))
+		return -ENOMEM;
+
+	lru_add_drain();
+	tlb_gather_mmu(&tlb, mm);
+	next = vma_next(&vmi);
+	if (new_end > old_start) {
+		/*
+		 * when the old and new regions overlap clear from new_end.
+		 */
+		free_pgd_range(&tlb, new_end, old_end, new_end,
+			next ? next->vm_start : USER_PGTABLES_CEILING);
+	} else {
+		/*
+		 * otherwise, clean from old_start; this is done to not touch
+		 * the address space in [new_end, old_start) some architectures
+		 * have constraints on va-space that make this illegal (IA64) -
+		 * for the others its just a little faster.
+		 */
+		free_pgd_range(&tlb, old_start, old_end, new_end,
+			next ? next->vm_start : USER_PGTABLES_CEILING);
+	}
+	tlb_finish_mmu(&tlb);
+
+	vma_prev(&vmi);
+	/* Shrink the vma to just the new range */
+	return vma_shrink(&vmi, vma, new_start, new_end, vma->vm_pgoff);
+}