Merge tag 'mm-stable-2023-04-27-15-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

 - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of
   switching from a user process to a kernel thread.

 - More folio conversions from Kefeng Wang, Zhang Peng and Pankaj
   Raghav.

 - zsmalloc performance improvements from Sergey Senozhatsky.

 - Yue Zhao has found and fixed some data race issues around the
   alteration of memcg userspace tunables.

 - VFS rationalizations from Christoph Hellwig:
     - removal of most of the callers of write_one_page()
     - make __filemap_get_folio()'s return value more useful

 - Luis Chamberlain has changed tmpfs so it no longer requires swap
   backing. Use `mount -o noswap'.

 - Qi Zheng has made the slab shrinkers operate locklessly, providing
   some scalability benefits.

 - Keith Busch has improved dmapool's performance, making part of its
   operations O(1) rather than O(n).

 - Peter Xu adds the UFFD_FEATURE_WP_UNPOPULATED feature to userfaultd,
   permitting userspace to wr-protect anon memory unpopulated ptes.

 - Kirill Shutemov has changed MAX_ORDER's meaning to be inclusive
   rather than exclusive, and has fixed a bunch of errors which were
   caused by its unintuitive meaning.

 - Axel Rasmussen give userfaultfd the UFFDIO_CONTINUE_MODE_WP feature,
   which causes minor faults to install a write-protected pte.

 - Vlastimil Babka has done some maintenance work on vma_merge():
   cleanups to the kernel code and improvements to our userspace test
   harness.

 - Cleanups to do_fault_around() by Lorenzo Stoakes.

 - Mike Rapoport has moved a lot of initialization code out of various
   mm/ files and into mm/mm_init.c.

 - Lorenzo Stoakes removd vmf_insert_mixed_prot(), which was added for
   DRM, but DRM doesn't use it any more.

 - Lorenzo has also coverted read_kcore() and vread() to use iterators
   and has thereby removed the use of bounce buffers in some cases.

 - Lorenzo has also contributed further cleanups of vma_merge().

 - Chaitanya Prakash provides some fixes to the mmap selftesting code.

 - Matthew Wilcox changes xfs and afs so they no longer take sleeping
   locks in ->map_page(), a step towards RCUification of pagefaults.

 - Suren Baghdasaryan has improved mmap_lock scalability by switching to
   per-VMA locking.

 - Frederic Weisbecker has reworked the percpu cache draining so that it
   no longer causes latency glitches on cpu isolated workloads.

 - Mike Rapoport cleans up and corrects the ARCH_FORCE_MAX_ORDER Kconfig
   logic.

 - Liu Shixin has changed zswap's initialization so we no longer waste a
   chunk of memory if zswap is not being used.

 - Yosry Ahmed has improved the performance of memcg statistics
   flushing.

 - David Stevens has fixed several issues involving khugepaged,
   userfaultfd and shmem.

 - Christoph Hellwig has provided some cleanup work to zram's IO-related
   code paths.

 - David Hildenbrand has fixed up some issues in the selftest code's
   testing of our pte state changing.

 - Pankaj Raghav has made page_endio() unneeded and has removed it.

 - Peter Xu contributed some rationalizations of the userfaultfd
   selftests.

 - Yosry Ahmed has fixed an issue around memcg's page recalim
   accounting.

 - Chaitanya Prakash has fixed some arm-related issues in the
   selftests/mm code.

 - Longlong Xia has improved the way in which KSM handles hwpoisoned
   pages.

 - Peter Xu fixes a few issues with uffd-wp at fork() time.

 - Stefan Roesch has changed KSM so that it may now be used on a
   per-process and per-cgroup basis.

* tag 'mm-stable-2023-04-27-15-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (369 commits)
  mm,unmap: avoid flushing TLB in batch if PTE is inaccessible
  shmem: restrict noswap option to initial user namespace
  mm/khugepaged: fix conflicting mods to collapse_file()
  sparse: remove unnecessary 0 values from rc
  mm: move 'mmap_min_addr' logic from callers into vm_unmapped_area()
  hugetlb: pte_alloc_huge() to replace huge pte_alloc_map()
  maple_tree: fix allocation in mas_sparse_area()
  mm: do not increment pgfault stats when page fault handler retries
  zsmalloc: allow only one active pool compaction context
  selftests/mm: add new selftests for KSM
  mm: add new KSM process and sysfs knobs
  mm: add new api to enable ksm per process
  mm: shrinkers: fix debugfs file permissions
  mm: don't check VMA write permissions if the PTE/PMD indicates write permissions
  migrate_pages_batch: fix statistics for longterm pin retry
  userfaultfd: use helper function range_in_vma()
  lib/show_mem.c: use for_each_populated_zone() simplify code
  mm: correct arg in reclaim_pages()/reclaim_clean_pages_from_list()
  fs/buffer: convert create_page_buffers to folio_create_buffers
  fs/buffer: add folio_create_empty_buffers helper
  ...

1 files changed, 171 insertions, 119 deletions

diff --git a/mm/mmap.c b/mm/mmap.c
index eefa6f0cda28e..5522130ae6065 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -46,6 +46,7 @@
 #include <linux/pkeys.h>
 #include <linux/oom.h>
 #include <linux/sched/mm.h>
+#include <linux/ksm.h>
 
 #include <linux/uaccess.h>
 #include <asm/cacheflush.h>
@@ -133,7 +134,7 @@ void unlink_file_vma(struct vm_area_struct *vma)
 /*
  * Close a vm structure and free it.
  */
-static void remove_vma(struct vm_area_struct *vma)
+static void remove_vma(struct vm_area_struct *vma, bool unreachable)
 {
 	might_sleep();
 	if (vma->vm_ops && vma->vm_ops->close)
@@ -141,7 +142,10 @@ static void remove_vma(struct vm_area_struct *vma)
 	if (vma->vm_file)
 		fput(vma->vm_file);
 	mpol_put(vma_policy(vma));
-	vm_area_free(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,
@@ -502,6 +506,15 @@ static inline void init_vma_prep(struct vma_prepare *vp,
  */
 static inline void vma_prepare(struct vma_prepare *vp)
 {
+	vma_start_write(vp->vma);
+	if (vp->adj_next)
+		vma_start_write(vp->adj_next);
+	/* vp->insert is always a newly created VMA, no need for locking */
+	if (vp->remove)
+		vma_start_write(vp->remove);
+	if (vp->remove2)
+		vma_start_write(vp->remove2);
+
 	if (vp->file) {
 		uprobe_munmap(vp->vma, vp->vma->vm_start, vp->vma->vm_end);
 
@@ -590,6 +603,7 @@ static inline void vma_complete(struct vma_prepare *vp,
 
 	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);
@@ -605,7 +619,7 @@ again:
 
 		/*
 		 * In mprotect's case 6 (see comments on vma_merge),
-		 * we must remove the one after next as well.
+		 * we are removing both mid and next vmas
 		 */
 		if (vp->remove2) {
 			vp->remove = vp->remove2;
@@ -683,12 +697,12 @@ int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma,
 	if (vma_iter_prealloc(vmi))
 		goto nomem;
 
+	vma_prepare(&vp);
 	vma_adjust_trans_huge(vma, start, end, 0);
 	/* VMA iterator points to previous, so set to start if necessary */
 	if (vma_iter_addr(vmi) != start)
 		vma_iter_set(vmi, start);
 
-	vma_prepare(&vp);
 	vma->vm_start = start;
 	vma->vm_end = end;
 	vma->vm_pgoff = pgoff;
@@ -723,8 +737,8 @@ int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma,
 		return -ENOMEM;
 
 	init_vma_prep(&vp, vma);
-	vma_adjust_trans_huge(vma, start, end, 0);
 	vma_prepare(&vp);
+	vma_adjust_trans_huge(vma, start, end, 0);
 
 	if (vma->vm_start < start)
 		vma_iter_clear(vmi, vma->vm_start, start);
@@ -742,12 +756,13 @@ int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma,
 
 /*
  * 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.
+ * 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 int 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)
+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
@@ -758,21 +773,20 @@ static inline int is_mergeable_vma(struct vm_area_struct *vma,
 	 * extended instead.
 	 */
 	if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
-		return 0;
+		return false;
 	if (vma->vm_file != file)
-		return 0;
-	if (vma->vm_ops && vma->vm_ops->close)
-		return 0;
+		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 0;
+		return false;
 	if (!anon_vma_name_eq(anon_vma_name(vma), anon_name))
-		return 0;
-	return 1;
+		return false;
+	return true;
 }
 
-static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
-					struct anon_vma *anon_vma2,
-					struct vm_area_struct *vma)
+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
@@ -780,7 +794,7 @@ static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
 	 */
 	if ((!anon_vma1 || !anon_vma2) && (!vma ||
 		list_is_singular(&vma->anon_vma_chain)))
-		return 1;
+		return true;
 	return anon_vma1 == anon_vma2;
 }
 
@@ -794,20 +808,21 @@ static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
  * 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 int
+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)
+		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) &&
+	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 1;
+			return true;
 	}
-	return 0;
+	return false;
 }
 
 /*
@@ -816,22 +831,23 @@ can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
  *
  * 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 int
+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)
+		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) &&
+	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 1;
+			return true;
 	}
-	return 0;
+	return false;
 }
 
 /*
@@ -846,42 +862,45 @@ can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
  * 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 AAAA is
+ * The following mprotect cases have to be considered, where **** is
  * the area passed down from mprotect_fixup, never extending beyond one
- * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
+ * 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 ****:
  *
- *     AAAA             AAAA                   AAAA
- *    PPPPPPNNNNNN    PPPPPPNNNNNN       PPPPPPNNNNNN
+ *     ****             ****                   ****
+ *    PPPPPPNNNNNN    PPPPPPNNNNNN       PPPPPPCCCCCC
  *    cannot merge    might become       might become
- *                    PPNNNNNNNNNN       PPPPPPPPPPNN
+ *                    PPNNNNNNNNNN       PPPPPPPPPPCC
  *    mmap, brk or    case 4 below       case 5 below
  *    mremap move:
- *                        AAAA               AAAA
- *                    PPPP    NNNN       PPPPNNNNXXXX
+ *                        ****               ****
+ *                    PPPP    NNNN       PPPPCCCCNNNN
  *                    might become       might become
  *                    PPPPPPPPPPPP 1 or  PPPPPPPPPPPP 6 or
- *                    PPPPPPPPNNNN 2 or  PPPPPPPPXXXX 7 or
- *                    PPPPNNNNNNNN 3     PPPPXXXXXXXX 8
+ *                    PPPPPPPPNNNN 2 or  PPPPPPPPNNNN 7 or
+ *                    PPPPNNNNNNNN 3     PPPPNNNNNNNN 8
  *
- * It is important for case 8 that the vma NNNN overlapping the
- * region AAAA is never going to extended over XXXX. Instead XXXX must
- * be extended in region AAAA and NNNN must be removed. This way in
+ * 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 XXXX would be removed and
- * NNNN would be extended over the XXXX range, remove_migration_ptes
+ * 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 NNNN
- * instead of the right permissions of XXXX.
+ * 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
- * NNNN is represented by *mid (and possibly equal to *next)
- * XXXX is represented by *next or not represented at all.
- * AAAA is not represented - it will be merged or the function will return NULL
+ * 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
  */
 struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm,
 			struct vm_area_struct *prev, unsigned long addr,
@@ -891,18 +910,18 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm,
 			struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
 			struct anon_vma_name *anon_name)
 {
-	pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
-	pgoff_t vma_pgoff;
-	struct vm_area_struct *mid, *next, *res = NULL;
+	struct vm_area_struct *curr, *next, *res;
 	struct vm_area_struct *vma, *adjust, *remove, *remove2;
-	int err = -1;
+	struct vma_prepare vp;
+	pgoff_t vma_pgoff;
+	int err = 0;
 	bool merge_prev = false;
 	bool merge_next = false;
 	bool vma_expanded = false;
-	struct vma_prepare vp;
-	unsigned long vma_end = end;
-	long adj_next = 0;
 	unsigned long vma_start = addr;
+	unsigned long vma_end = end;
+	pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
+	long adj_start = 0;
 
 	validate_mm(mm);
 	/*
@@ -912,94 +931,105 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm,
 	if (vm_flags & VM_SPECIAL)
 		return NULL;
 
-	next = find_vma(mm, prev ? prev->vm_end : 0);
-	mid = next;
-	if (next && next->vm_end == end)		/* cases 6, 7, 8 */
-		next = find_vma(mm, next->vm_end);
+	/* Does the input range span an existing VMA? (cases 5 - 8) */
+	curr = find_vma_intersection(mm, prev ? prev->vm_end : 0, end);
 
-	/* verify some invariant that must be enforced by the caller */
-	VM_WARN_ON(prev && addr <= prev->vm_start);
-	VM_WARN_ON(mid && end > mid->vm_end);
-	VM_WARN_ON(addr >= 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) {
-		res = prev;
-		vma = prev;
 		vma_start = prev->vm_start;
 		vma_pgoff = prev->vm_pgoff;
+
 		/* Can we merge the predecessor? */
-		if (prev->vm_end == addr && mpol_equal(vma_policy(prev), policy)
+		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)) {
+					   pgoff, vm_userfaultfd_ctx, anon_name)) {
 			merge_prev = true;
 			vma_prev(vmi);
 		}
 	}
+
 	/* Can we merge the successor? */
-	if (next && end == next->vm_start &&
-			mpol_equal(policy, vma_policy(next)) &&
-			can_vma_merge_before(next, vm_flags,
-					     anon_vma, file, pgoff+pglen,
-					     vm_userfaultfd_ctx, anon_name)) {
+	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;
 	}
 
+	if (!merge_prev && !merge_next)
+		return NULL; /* Not mergeable. */
+
+	res = vma = prev;
 	remove = remove2 = adjust = NULL;
+
+	/* 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);
+
 	/* 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)) {
-		remove = mid;				/* case 1 */
+		remove = next;				/* case 1 */
 		vma_end = next->vm_end;
-		err = dup_anon_vma(res, remove);
-		if (mid != next) {			/* case 6 */
+		err = dup_anon_vma(prev, next);
+		if (curr) {				/* case 6 */
+			remove = curr;
 			remove2 = next;
-			if (!remove->anon_vma)
-				err = dup_anon_vma(res, remove2);
+			if (!next->anon_vma)
+				err = dup_anon_vma(prev, curr);
 		}
-	} else if (merge_prev) {
-		err = 0;				/* case 2 */
-		if (mid && end > mid->vm_start) {
-			err = dup_anon_vma(res, mid);
-			if (end == mid->vm_end) {	/* case 7 */
-				remove = mid;
+	} else if (merge_prev) {			/* case 2 */
+		if (curr) {
+			err = dup_anon_vma(prev, curr);
+			if (end == curr->vm_end) {	/* case 7 */
+				remove = curr;
 			} else {			/* case 5 */
-				adjust = mid;
-				adj_next = (end - mid->vm_start);
+				adjust = curr;
+				adj_start = (end - curr->vm_start);
 			}
 		}
-	} else if (merge_next) {
+	} else { /* merge_next */
 		res = next;
 		if (prev && addr < prev->vm_end) {	/* case 4 */
 			vma_end = addr;
-			adjust = mid;
-			adj_next = -(vma->vm_end - addr);
-			err = dup_anon_vma(adjust, prev);
+			adjust = next;
+			adj_start = -(prev->vm_end - addr);
+			err = dup_anon_vma(next, prev);
 		} 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;
-			err = 0;
-			if (mid != next) {		/* case 8 */
-				remove = mid;
-				err = dup_anon_vma(res, remove);
+			if (curr) {			/* case 8 */
+				vma_pgoff = curr->vm_pgoff;
+				remove = curr;
+				err = dup_anon_vma(next, curr);
 			}
 		}
 	}
 
-	/* Cannot merge or error in anon_vma clone */
+	/* Error in anon_vma clone. */
 	if (err)
 		return NULL;
 
 	if (vma_iter_prealloc(vmi))
 		return NULL;
 
-	vma_adjust_trans_huge(vma, vma_start, vma_end, adj_next);
 	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);
 	if (vma_start < vma->vm_start || vma_end > vma->vm_end)
 		vma_expanded = true;
 
@@ -1010,10 +1040,10 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm,
 	if (vma_expanded)
 		vma_iter_store(vmi, vma);
 
-	if (adj_next) {
-		adjust->vm_start += adj_next;
-		adjust->vm_pgoff += adj_next >> PAGE_SHIFT;
-		if (adj_next < 0) {
+	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);
 		}
@@ -1518,7 +1548,8 @@ static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
  */
 static unsigned long unmapped_area(struct vm_unmapped_area_info *info)
 {
-	unsigned long length, gap, low_limit;
+	unsigned long length, gap;
+	unsigned long low_limit, high_limit;
 	struct vm_area_struct *tmp;
 
 	MA_STATE(mas, &current->mm->mm_mt, 0, 0);
@@ -1529,8 +1560,11 @@ static unsigned long unmapped_area(struct vm_unmapped_area_info *info)
 		return -ENOMEM;
 
 	low_limit = info->low_limit;
+	if (low_limit < mmap_min_addr)
+		low_limit = mmap_min_addr;
+	high_limit = info->high_limit;
 retry:
-	if (mas_empty_area(&mas, low_limit, info->high_limit - 1, length))
+	if (mas_empty_area(&mas, low_limit, high_limit - 1, length))
 		return -ENOMEM;
 
 	gap = mas.index;
@@ -1566,7 +1600,8 @@ retry:
  */
 static unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
 {
-	unsigned long length, gap, high_limit, gap_end;
+	unsigned long length, gap, gap_end;
+	unsigned long low_limit, high_limit;
 	struct vm_area_struct *tmp;
 
 	MA_STATE(mas, &current->mm->mm_mt, 0, 0);
@@ -1575,10 +1610,12 @@ static unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
 	if (length < info->length)
 		return -ENOMEM;
 
+	low_limit = info->low_limit;
+	if (low_limit < mmap_min_addr)
+		low_limit = mmap_min_addr;
 	high_limit = info->high_limit;
 retry:
-	if (mas_empty_area_rev(&mas, info->low_limit, high_limit - 1,
-				length))
+	if (mas_empty_area_rev(&mas, low_limit, high_limit - 1, length))
 		return -ENOMEM;
 
 	gap = mas.last + 1 - info->length;
@@ -1713,7 +1750,7 @@ generic_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
 
 	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
 	info.length = len;
-	info.low_limit = max(PAGE_SIZE, mmap_min_addr);
+	info.low_limit = PAGE_SIZE;
 	info.high_limit = arch_get_mmap_base(addr, mm->mmap_base);
 	info.align_mask = 0;
 	info.align_offset = 0;
@@ -2157,7 +2194,7 @@ static inline void remove_mt(struct mm_struct *mm, struct ma_state *mas)
 		if (vma->vm_flags & VM_ACCOUNT)
 			nr_accounted += nrpages;
 		vm_stat_account(mm, vma->vm_flags, -nrpages);
-		remove_vma(vma);
+		remove_vma(vma, false);
 	}
 	vm_unacct_memory(nr_accounted);
 	validate_mm(mm);
@@ -2180,7 +2217,8 @@ static void unmap_region(struct mm_struct *mm, struct maple_tree *mt,
 	update_hiwater_rss(mm);
 	unmap_vmas(&tlb, mt, vma, start, end, mm_wr_locked);
 	free_pgtables(&tlb, mt, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
-				 next ? next->vm_start : USER_PGTABLES_CEILING);
+				 next ? next->vm_start : USER_PGTABLES_CEILING,
+				 mm_wr_locked);
 	tlb_finish_mmu(&tlb);
 }
 
@@ -2236,10 +2274,10 @@ int __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
 	if (new->vm_ops && new->vm_ops->open)
 		new->vm_ops->open(new);
 
-	vma_adjust_trans_huge(vma, vma->vm_start, addr, 0);
 	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;
@@ -2283,10 +2321,12 @@ int split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
 static inline int munmap_sidetree(struct vm_area_struct *vma,
 				   struct ma_state *mas_detach)
 {
+	vma_start_write(vma);
 	mas_set_range(mas_detach, vma->vm_start, vma->vm_end - 1);
 	if (mas_store_gfp(mas_detach, vma, GFP_KERNEL))
 		return -ENOMEM;
 
+	vma_mark_detached(vma, true);
 	if (vma->vm_flags & VM_LOCKED)
 		vma->vm_mm->locked_vm -= vma_pages(vma);
 
@@ -2697,6 +2737,7 @@ unmap_writable:
 	if (file && vm_flags & VM_SHARED)
 		mapping_unmap_writable(file->f_mapping);
 	file = vma->vm_file;
+	ksm_add_vma(vma);
 expanded:
 	perf_event_mmap(vma);
 
@@ -2942,9 +2983,9 @@ static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma,
 		if (vma_iter_prealloc(vmi))
 			goto unacct_fail;
 
-		vma_adjust_trans_huge(vma, vma->vm_start, addr + len, 0);
 		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);
@@ -2969,6 +3010,7 @@ static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma,
 		goto mas_store_fail;
 
 	mm->map_count++;
+	ksm_add_vma(vma);
 out:
 	perf_event_mmap(vma);
 	mm->total_vm += len >> PAGE_SHIFT;
@@ -3077,7 +3119,7 @@ void exit_mmap(struct mm_struct *mm)
 	mmap_write_lock(mm);
 	mt_clear_in_rcu(&mm->mm_mt);
 	free_pgtables(&tlb, &mm->mm_mt, vma, FIRST_USER_ADDRESS,
-		      USER_PGTABLES_CEILING);
+		      USER_PGTABLES_CEILING, true);
 	tlb_finish_mmu(&tlb);
 
 	/*
@@ -3088,7 +3130,7 @@ void exit_mmap(struct mm_struct *mm)
 	do {
 		if (vma->vm_flags & VM_ACCOUNT)
 			nr_accounted += vma_pages(vma);
-		remove_vma(vma);
+		remove_vma(vma, true);
 		count++;
 		cond_resched();
 	} while ((vma = mas_find(&mas, ULONG_MAX)) != NULL);
@@ -3211,6 +3253,7 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
 			get_file(new_vma->vm_file);
 		if (new_vma->vm_ops && new_vma->vm_ops->open)
 			new_vma->vm_ops->open(new_vma);
+		vma_start_write(new_vma);
 		if (vma_link(mm, new_vma))
 			goto out_vma_link;
 		*need_rmap_locks = false;
@@ -3505,6 +3548,7 @@ static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
  * 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
  *
@@ -3530,6 +3574,13 @@ int mm_take_all_locks(struct mm_struct *mm)
 	mas_for_each(&mas, vma, ULONG_MAX) {
 		if (signal_pending(current))
 			goto out_unlock;
+		vma_start_write(vma);
+	}
+
+	mas_set(&mas, 0);
+	mas_for_each(&mas, vma, ULONG_MAX) {
+		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);
@@ -3616,6 +3667,7 @@ void mm_drop_all_locks(struct mm_struct *mm)
 		if (vma->vm_file && vma->vm_file->f_mapping)
 			vm_unlock_mapping(vma->vm_file->f_mapping);
 	}
+	vma_end_write_all(mm);
 
 	mutex_unlock(&mm_all_locks_mutex);
 }