[PATCH v10 67/69] mm: remove the vma linked list

From: Liam Howlett <liam.howlett@oracle.com>
To: "maple-tree@lists.infradead.org" <maple-tree@lists.infradead.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	"damon @ lists . linux . dev" <damon@lists.linux.dev>,
	SeongJae Park <sj@kernel.org>,
	David Hildenbrand <david@redhat.com>
Subject: [PATCH v10 67/69] mm: remove the vma linked list
Date: Tue, 21 Jun 2022 20:47:14 +0000	[thread overview]
Message-ID: <20220621204632.3370049-68-Liam.Howlett@oracle.com> (raw)
In-Reply-To: <20220621204632.3370049-1-Liam.Howlett@oracle.com>

From: "Liam R. Howlett" <Liam.Howlett@Oracle.com>

Replace any vm_next use with vma_find().

Update free_pgtables(), unmap_vmas(), and zap_page_range() to use the
maple tree.

Use the new free_pgtables() and unmap_vmas() in do_mas_align_munmap().  At
the same time, alter the loop to be more compact.

Now that free_pgtables() and unmap_vmas() take a maple tree as an
argument, rearrange do_mas_align_munmap() to use the new tree to hold the
vmas to remove.

Remove __vma_link_list() and __vma_unlink_list() as they are exclusively
used to update the linked list

Drop linked list update from __insert_vm_struct().

Rework validation of tree as it was depending on the linked list.

Link: https://lkml.kernel.org/r/20220504011345.662299-52-Liam.Howlett@oracle.com
Link: https://lkml.kernel.org/r/20220513141548.2019143-1-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: SeongJae Park <sj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 include/linux/mm.h       |   5 +-
 include/linux/mm_types.h |   4 -
 kernel/fork.c            |  19 +-
 mm/debug.c               |  14 +-
 mm/internal.h            |   8 +-
 mm/memory.c              |  33 ++-
 mm/mmap.c                | 447 +++++++++++++++++----------------------
 mm/nommu.c               |   6 -
 mm/util.c                |  40 ----
 9 files changed, 229 insertions(+), 347 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 890459c69f74..d2770a5bf578 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1873,8 +1873,9 @@ void zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
 		  unsigned long size);
 void zap_page_range(struct vm_area_struct *vma, unsigned long address,
 		    unsigned long size);
-void unmap_vmas(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
-		unsigned long start, unsigned long end);
+void unmap_vmas(struct mmu_gather *tlb, struct maple_tree *mt,
+		struct vm_area_struct *start_vma, unsigned long start,
+		unsigned long end);
 
 struct mmu_notifier_range;
 
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 070468f521dd..52e853e44a23 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -403,8 +403,6 @@ struct vm_area_struct {
 	unsigned long vm_end;		/* The first byte after our end address
 					   within vm_mm. */
 
-	/* linked list of VM areas per task, sorted by address */
-	struct vm_area_struct *vm_next, *vm_prev;
 	struct mm_struct *vm_mm;	/* The address space we belong to. */
 
 	/*
@@ -468,7 +466,6 @@ struct vm_area_struct {
 struct kioctx_table;
 struct mm_struct {
 	struct {
-		struct vm_area_struct *mmap;		/* list of VMAs */
 		struct maple_tree mm_mt;
 #ifdef CONFIG_MMU
 		unsigned long (*get_unmapped_area) (struct file *filp,
@@ -483,7 +480,6 @@ struct mm_struct {
 		unsigned long mmap_compat_legacy_base;
 #endif
 		unsigned long task_size;	/* size of task vm space */
-		unsigned long highest_vm_end;	/* highest vma end address */
 		pgd_t * pgd;
 
 #ifdef CONFIG_MEMBARRIER
diff --git a/kernel/fork.c b/kernel/fork.c
index 7fcefef4c84d..889f318db3c1 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -474,7 +474,6 @@ struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
 		 */
 		*new = data_race(*orig);
 		INIT_LIST_HEAD(&new->anon_vma_chain);
-		new->vm_next = new->vm_prev = NULL;
 		dup_anon_vma_name(orig, new);
 	}
 	return new;
@@ -579,7 +578,7 @@ static void dup_mm_exe_file(struct mm_struct *mm, struct mm_struct *oldmm)
 static __latent_entropy int dup_mmap(struct mm_struct *mm,
 					struct mm_struct *oldmm)
 {
-	struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
+	struct vm_area_struct *mpnt, *tmp;
 	int retval;
 	unsigned long charge = 0;
 	MA_STATE(old_mas, &oldmm->mm_mt, 0, 0);
@@ -606,18 +605,11 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
 	mm->exec_vm = oldmm->exec_vm;
 	mm->stack_vm = oldmm->stack_vm;
 
-	pprev = &mm->mmap;
 	retval = ksm_fork(mm, oldmm);
 	if (retval)
 		goto out;
 	khugepaged_fork(mm, oldmm);
 
-	retval = mas_expected_entries(&mas, oldmm->map_count);
-	if (retval)
-		goto out;
-
-	prev = NULL;
-
 	retval = mas_expected_entries(&mas, oldmm->map_count);
 	if (retval)
 		goto out;
@@ -689,14 +681,6 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
 		if (is_vm_hugetlb_page(tmp))
 			reset_vma_resv_huge_pages(tmp);
 
-		/*
-		 * Link in the new vma and copy the page table entries.
-		 */
-		*pprev = tmp;
-		pprev = &tmp->vm_next;
-		tmp->vm_prev = prev;
-		prev = tmp;
-
 		/* Link the vma into the MT */
 		mas.index = tmp->vm_start;
 		mas.last = tmp->vm_end - 1;
@@ -1119,7 +1103,6 @@ static void mm_init_uprobes_state(struct mm_struct *mm)
 static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
 	struct user_namespace *user_ns)
 {
-	mm->mmap = NULL;
 	mt_init_flags(&mm->mm_mt, MM_MT_FLAGS);
 	mt_set_external_lock(&mm->mm_mt, &mm->mmap_lock);
 	atomic_set(&mm->mm_users, 1);
diff --git a/mm/debug.c b/mm/debug.c
index 2d625ca0e326..0fd15ba70d16 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -139,13 +139,11 @@ EXPORT_SYMBOL(dump_page);
 
 void dump_vma(const struct vm_area_struct *vma)
 {
-	pr_emerg("vma %px start %px end %px\n"
-		"next %px prev %px mm %px\n"
+	pr_emerg("vma %px start %px end %px mm %px\n"
 		"prot %lx anon_vma %px vm_ops %px\n"
 		"pgoff %lx file %px private_data %px\n"
 		"flags: %#lx(%pGv)\n",
-		vma, (void *)vma->vm_start, (void *)vma->vm_end, vma->vm_next,
-		vma->vm_prev, vma->vm_mm,
+		vma, (void *)vma->vm_start, (void *)vma->vm_end, vma->vm_mm,
 		(unsigned long)pgprot_val(vma->vm_page_prot),
 		vma->anon_vma, vma->vm_ops, vma->vm_pgoff,
 		vma->vm_file, vma->vm_private_data,
@@ -155,11 +153,11 @@ EXPORT_SYMBOL(dump_vma);
 
 void dump_mm(const struct mm_struct *mm)
 {
-	pr_emerg("mm %px mmap %px task_size %lu\n"
+	pr_emerg("mm %px task_size %lu\n"
 #ifdef CONFIG_MMU
 		"get_unmapped_area %px\n"
 #endif
-		"mmap_base %lu mmap_legacy_base %lu highest_vm_end %lu\n"
+		"mmap_base %lu mmap_legacy_base %lu\n"
 		"pgd %px mm_users %d mm_count %d pgtables_bytes %lu map_count %d\n"
 		"hiwater_rss %lx hiwater_vm %lx total_vm %lx locked_vm %lx\n"
 		"pinned_vm %llx data_vm %lx exec_vm %lx stack_vm %lx\n"
@@ -183,11 +181,11 @@ void dump_mm(const struct mm_struct *mm)
 		"tlb_flush_pending %d\n"
 		"def_flags: %#lx(%pGv)\n",
 
-		mm, mm->mmap, mm->task_size,
+		mm, mm->task_size,
 #ifdef CONFIG_MMU
 		mm->get_unmapped_area,
 #endif
-		mm->mmap_base, mm->mmap_legacy_base, mm->highest_vm_end,
+		mm->mmap_base, mm->mmap_legacy_base,
 		mm->pgd, atomic_read(&mm->mm_users),
 		atomic_read(&mm->mm_count),
 		mm_pgtables_bytes(mm),
diff --git a/mm/internal.h b/mm/internal.h
index c0f8fbe0445b..7d6964e3ba01 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -84,8 +84,9 @@ void folio_rotate_reclaimable(struct folio *folio);
 bool __folio_end_writeback(struct folio *folio);
 void deactivate_file_folio(struct folio *folio);
 
-void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
-		unsigned long floor, unsigned long ceiling);
+void free_pgtables(struct mmu_gather *tlb, struct maple_tree *mt,
+		   struct vm_area_struct *start_vma, unsigned long floor,
+		   unsigned long ceiling);
 void pmd_install(struct mm_struct *mm, pmd_t *pmd, pgtable_t *pte);
 
 struct zap_details;
@@ -479,9 +480,6 @@ static inline bool is_data_mapping(vm_flags_t flags)
 }
 
 /* mm/util.c */
-void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
-		struct vm_area_struct *prev);
-void __vma_unlink_list(struct mm_struct *mm, struct vm_area_struct *vma);
 struct anon_vma *folio_anon_vma(struct folio *folio);
 
 #ifdef CONFIG_MMU
diff --git a/mm/memory.c b/mm/memory.c
index 7a089145cad4..eecfce0750ec 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -402,12 +402,21 @@ void free_pgd_range(struct mmu_gather *tlb,
 	} while (pgd++, addr = next, addr != end);
 }
 
-void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
-		unsigned long floor, unsigned long ceiling)
+void free_pgtables(struct mmu_gather *tlb, struct maple_tree *mt,
+		   struct vm_area_struct *vma, unsigned long floor,
+		   unsigned long ceiling)
 {
-	while (vma) {
-		struct vm_area_struct *next = vma->vm_next;
+	MA_STATE(mas, mt, vma->vm_end, vma->vm_end);
+
+	do {
 		unsigned long addr = vma->vm_start;
+		struct vm_area_struct *next;
+
+		/*
+		 * Note: USER_PGTABLES_CEILING may be passed as ceiling and may
+		 * be 0.  This will underflow and is okay.
+		 */
+		next = mas_find(&mas, ceiling - 1);
 
 		/*
 		 * Hide vma from rmap and truncate_pagecache before freeing
@@ -426,7 +435,7 @@ void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
 			while (next && next->vm_start <= vma->vm_end + PMD_SIZE
 			       && !is_vm_hugetlb_page(next)) {
 				vma = next;
-				next = vma->vm_next;
+				next = mas_find(&mas, ceiling - 1);
 				unlink_anon_vmas(vma);
 				unlink_file_vma(vma);
 			}
@@ -434,7 +443,7 @@ void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
 				floor, next ? next->vm_start : ceiling);
 		}
 		vma = next;
-	}
+	} while (vma);
 }
 
 void pmd_install(struct mm_struct *mm, pmd_t *pmd, pgtable_t *pte)
@@ -1705,7 +1714,7 @@ static void unmap_single_vma(struct mmu_gather *tlb,
  * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
  * drops the lock and schedules.
  */
-void unmap_vmas(struct mmu_gather *tlb,
+void unmap_vmas(struct mmu_gather *tlb, struct maple_tree *mt,
 		struct vm_area_struct *vma, unsigned long start_addr,
 		unsigned long end_addr)
 {
@@ -1715,12 +1724,14 @@ void unmap_vmas(struct mmu_gather *tlb,
 		/* Careful - we need to zap private pages too! */
 		.even_cows = true,
 	};
+	MA_STATE(mas, mt, vma->vm_end, vma->vm_end);
 
 	mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma, vma->vm_mm,
 				start_addr, end_addr);
 	mmu_notifier_invalidate_range_start(&range);
-	for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
+	do {
 		unmap_single_vma(tlb, vma, start_addr, end_addr, &details);
+	} while ((vma = mas_find(&mas, end_addr - 1)) != NULL);
 	mmu_notifier_invalidate_range_end(&range);
 }
 
@@ -1735,8 +1746,11 @@ void unmap_vmas(struct mmu_gather *tlb,
 void zap_page_range(struct vm_area_struct *vma, unsigned long start,
 		unsigned long size)
 {
+	struct maple_tree *mt = &vma->vm_mm->mm_mt;
+	unsigned long end = start + size;
 	struct mmu_notifier_range range;
 	struct mmu_gather tlb;
+	MA_STATE(mas, mt, vma->vm_end, vma->vm_end);
 
 	lru_add_drain();
 	mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
@@ -1744,8 +1758,9 @@ void zap_page_range(struct vm_area_struct *vma, unsigned long start,
 	tlb_gather_mmu(&tlb, vma->vm_mm);
 	update_hiwater_rss(vma->vm_mm);
 	mmu_notifier_invalidate_range_start(&range);
-	for ( ; vma && vma->vm_start < range.end; vma = vma->vm_next)
+	do {
 		unmap_single_vma(&tlb, vma, start, range.end, NULL);
+	} while ((vma = mas_find(&mas, end - 1)) != NULL);
 	mmu_notifier_invalidate_range_end(&range);
 	tlb_finish_mmu(&tlb);
 }
diff --git a/mm/mmap.c b/mm/mmap.c
index f5c2d46d17ec..507efa222b8a 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -75,9 +75,10 @@ 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,
+static void unmap_region(struct mm_struct *mm, struct maple_tree *mt,
 		struct vm_area_struct *vma, struct vm_area_struct *prev,
-		unsigned long start, unsigned long end);
+		struct vm_area_struct *next, unsigned long start,
+		unsigned long end);
 
 /* description of effects of mapping type and prot in current implementation.
  * this is due to the limited x86 page protection hardware.  The expected
@@ -177,12 +178,10 @@ void unlink_file_vma(struct vm_area_struct *vma)
 }
 
 /*
- * Close a vm structure and free it, returning the next.
+ * Close a vm structure and free it.
  */
-static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
+static void remove_vma(struct vm_area_struct *vma)
 {
-	struct vm_area_struct *next = vma->vm_next;
-
 	might_sleep();
 	if (vma->vm_ops && vma->vm_ops->close)
 		vma->vm_ops->close(vma);
@@ -190,7 +189,6 @@ static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
 		fput(vma->vm_file);
 	mpol_put(vma_policy(vma));
 	vm_area_free(vma);
-	return next;
 }
 
 /*
@@ -215,8 +213,7 @@ static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
 			 unsigned long newbrk, unsigned long oldbrk,
 			 struct list_head *uf);
 static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *brkvma,
-			unsigned long addr, unsigned long request,
-			unsigned long flags);
+		unsigned long addr, unsigned long request, unsigned long flags);
 SYSCALL_DEFINE1(brk, unsigned long, brk)
 {
 	unsigned long newbrk, oldbrk, origbrk;
@@ -285,7 +282,6 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
 		 * before calling do_brk_munmap().
 		 */
 		mm->brk = brk;
-		mas.last = oldbrk - 1;
 		ret = do_brk_munmap(&mas, brkvma, newbrk, oldbrk, &uf);
 		if (ret == 1)  {
 			downgraded = true;
@@ -340,42 +336,20 @@ extern void mt_dump(const struct maple_tree *mt);
 static void validate_mm_mt(struct mm_struct *mm)
 {
 	struct maple_tree *mt = &mm->mm_mt;
-	struct vm_area_struct *vma_mt, *vma = mm->mmap;
+	struct vm_area_struct *vma_mt;
 
 	MA_STATE(mas, mt, 0, 0);
-	mas_for_each(&mas, vma_mt, ULONG_MAX) {
-		if (xa_is_zero(vma_mt))
-			continue;
-
-		if (!vma)
-			break;
 
-		if ((vma != vma_mt) ||
-		    (vma->vm_start != vma_mt->vm_start) ||
-		    (vma->vm_end != vma_mt->vm_end) ||
-		    (vma->vm_start != mas.index) ||
-		    (vma->vm_end - 1 != mas.last)) {
+	mas_for_each(&mas, vma_mt, ULONG_MAX) {
+		if ((vma_mt->vm_start != mas.index) ||
+		    (vma_mt->vm_end - 1 != mas.last)) {
 			pr_emerg("issue in %s\n", current->comm);
 			dump_stack();
 			dump_vma(vma_mt);
-			pr_emerg("and vm_next\n");
-			dump_vma(vma->vm_next);
 			pr_emerg("mt piv: %px %lu - %lu\n", vma_mt,
 				 mas.index, mas.last);
 			pr_emerg("mt vma: %px %lu - %lu\n", vma_mt,
 				 vma_mt->vm_start, vma_mt->vm_end);
-			if (vma->vm_prev) {
-				pr_emerg("ll prev: %px %lu - %lu\n",
-					 vma->vm_prev, vma->vm_prev->vm_start,
-					 vma->vm_prev->vm_end);
-			}
-			pr_emerg("ll vma: %px %lu - %lu\n", vma,
-				 vma->vm_start, vma->vm_end);
-			if (vma->vm_next) {
-				pr_emerg("ll next: %px %lu - %lu\n",
-					 vma->vm_next, vma->vm_next->vm_start,
-					 vma->vm_next->vm_end);
-			}
 
 			mt_dump(mas.tree);
 			if (vma_mt->vm_end != mas.last + 1) {
@@ -392,11 +366,7 @@ static void validate_mm_mt(struct mm_struct *mm)
 			}
 			VM_BUG_ON_MM(vma_mt->vm_start != mas.index, mm);
 		}
-		VM_BUG_ON(vma != vma_mt);
-		vma = vma->vm_next;
-
 	}
-	VM_BUG_ON(vma);
 	mt_validate(&mm->mm_mt);
 }
 
@@ -404,12 +374,12 @@ static void validate_mm(struct mm_struct *mm)
 {
 	int bug = 0;
 	int i = 0;
-	unsigned long highest_address = 0;
-	struct vm_area_struct *vma = mm->mmap;
+	struct vm_area_struct *vma;
+	MA_STATE(mas, &mm->mm_mt, 0, 0);
 
 	validate_mm_mt(mm);
 
-	while (vma) {
+	mas_for_each(&mas, vma, ULONG_MAX) {
 #ifdef CONFIG_DEBUG_VM_RB
 		struct anon_vma *anon_vma = vma->anon_vma;
 		struct anon_vma_chain *avc;
@@ -421,18 +391,10 @@ static void validate_mm(struct mm_struct *mm)
 			anon_vma_unlock_read(anon_vma);
 		}
 #endif
-
-		highest_address = vm_end_gap(vma);
-		vma = vma->vm_next;
 		i++;
 	}
 	if (i != mm->map_count) {
-		pr_emerg("map_count %d vm_next %d\n", mm->map_count, i);
-		bug = 1;
-	}
-	if (highest_address != mm->highest_vm_end) {
-		pr_emerg("mm->highest_vm_end %lx, found %lx\n",
-			  mm->highest_vm_end, highest_address);
+		pr_emerg("map_count %d mas_for_each %d\n", mm->map_count, i);
 		bug = 1;
 	}
 	VM_BUG_ON_MM(bug, mm);
@@ -492,29 +454,13 @@ bool range_has_overlap(struct mm_struct *mm, unsigned long start,
 	struct vm_area_struct *existing;
 
 	MA_STATE(mas, &mm->mm_mt, start, start);
+	rcu_read_lock();
 	existing = mas_find(&mas, end - 1);
 	*pprev = mas_prev(&mas, 0);
+	rcu_read_unlock();
 	return existing ? true : false;
 }
 
-/*
- * __vma_next() - Get the next VMA.
- * @mm: The mm_struct.
- * @vma: The current vma.
- *
- * If @vma is NULL, return the first vma in the mm.
- *
- * Returns: The next VMA after @vma.
- */
-static inline struct vm_area_struct *__vma_next(struct mm_struct *mm,
-					 struct vm_area_struct *vma)
-{
-	if (!vma)
-		return mm->mmap;
-
-	return vma->vm_next;
-}
-
 static unsigned long count_vma_pages_range(struct mm_struct *mm,
 		unsigned long addr, unsigned long end)
 {
@@ -599,8 +545,7 @@ static inline void vma_mas_szero(struct ma_state *mas, unsigned long start,
 	mas_store_prealloc(mas, NULL);
 }
 
-static int vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
-			struct vm_area_struct *prev)
+static int vma_link(struct mm_struct *mm, struct vm_area_struct *vma)
 {
 	MA_STATE(mas, &mm->mm_mt, 0, 0);
 	struct address_space *mapping = NULL;
@@ -614,7 +559,6 @@ static int vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
 	}
 
 	vma_mas_store(vma, &mas);
-	__vma_link_list(mm, vma, prev);
 	__vma_link_file(vma);
 
 	if (mapping)
@@ -625,22 +569,6 @@ static int vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
 	return 0;
 }
 
-/*
- * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
- * mm's list and the mm tree.  It has already been inserted into the interval tree.
- */
-static void __insert_vm_struct(struct mm_struct *mm, struct ma_state *mas,
-		struct vm_area_struct *vma, unsigned long location)
-{
-	struct vm_area_struct *prev;
-
-	mas_set(mas, location);
-	prev = mas_prev(mas, 0);
-	vma_mas_store(vma, mas);
-	__vma_link_list(mm, vma, prev);
-	mm->map_count++;
-}
-
 /*
  * vma_expand - Expand an existing VMA
  *
@@ -719,15 +647,8 @@ inline int vma_expand(struct ma_state *mas, struct vm_area_struct *vma,
 	}
 
 	/* Expanding over the next vma */
-	if (remove_next) {
-		/* Remove from mm linked list - also updates highest_vm_end */
-		__vma_unlink_list(mm, next);
-
-		if (file)
-			__remove_shared_vm_struct(next, file, mapping);
-
-	} else if (!next) {
-		mm->highest_vm_end = vm_end_gap(vma);
+	if (remove_next && file) {
+		__remove_shared_vm_struct(next, file, mapping);
 	}
 
 	if (file) {
@@ -785,7 +706,6 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
 	int remove_next = 0;
 	MA_STATE(mas, &mm->mm_mt, 0, 0);
 	struct vm_area_struct *exporter = NULL, *importer = NULL;
-	unsigned long ll_prev = vma->vm_start; /* linked list prev. */
 
 	if (next && !insert) {
 		if (end >= next->vm_end) {
@@ -831,7 +751,7 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
 			 * next, if the vma overlaps with it.
 			 */
 			if (remove_next == 2 && !next->anon_vma)
-				exporter = next->vm_next;
+				exporter = find_vma(mm, next->vm_end);
 
 		} else if (end > next->vm_start) {
 			/*
@@ -930,17 +850,14 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
 		if (vma->vm_end > end) {
 			if (!insert || (insert->vm_start != end)) {
 				vma_mas_szero(&mas, end, vma->vm_end);
+				mas_reset(&mas);
 				VM_WARN_ON(insert &&
 					   insert->vm_end < vma->vm_end);
-			} else if (insert->vm_start == end) {
-				ll_prev = vma->vm_end;
 			}
 		} else {
 			vma_changed = true;
 		}
 		vma->vm_end = end;
-		if (!next)
-			mm->highest_vm_end = vm_end_gap(vma);
 	}
 
 	if (vma_changed)
@@ -960,17 +877,17 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
 		flush_dcache_mmap_unlock(mapping);
 	}
 
-	if (remove_next) {
-		__vma_unlink_list(mm, next);
-		if (file)
-			__remove_shared_vm_struct(next, file, mapping);
+	if (remove_next && file) {
+		__remove_shared_vm_struct(next, file, mapping);
 	} else if (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).
 		 */
-		__insert_vm_struct(mm, &mas, insert, ll_prev);
+		mas_reset(&mas);
+		vma_mas_store(insert, &mas);
+		mm->map_count++;
 	}
 
 	if (anon_vma) {
@@ -1009,8 +926,8 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
 			/*
 			 * If "next" was removed and vma->vm_end was
 			 * expanded (up) over it, in turn
-			 * "next->vm_prev->vm_end" changed and the
-			 * "vma->vm_next" gap must be updated.
+			 * "next->prev->vm_end" changed and the
+			 * "vma->next" gap must be updated.
 			 */
 			next = next_next;
 		} else {
@@ -1031,34 +948,15 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
 			remove_next = 1;
 			end = next->vm_end;
 			goto again;
-		} else if (!next) {
-			/*
-			 * If remove_next == 2 we obviously can't
-			 * reach this path.
-			 *
-			 * If remove_next == 3 we can't reach this
-			 * path because pre-swap() next is always not
-			 * NULL. pre-swap() "next" is not being
-			 * removed and its next->vm_end is not altered
-			 * (and furthermore "end" already matches
-			 * next->vm_end in remove_next == 3).
-			 *
-			 * We reach this only in the remove_next == 1
-			 * case if the "next" vma that was removed was
-			 * the highest vma of the mm. However in such
-			 * case next->vm_end == "end" and the extended
-			 * "vma" has vma->vm_end == next->vm_end so
-			 * mm->highest_vm_end doesn't need any update
-			 * in remove_next == 1 case.
-			 */
-			VM_WARN_ON(mm->highest_vm_end != vm_end_gap(vma));
 		}
 	}
-	if (insert && file)
+	if (insert && file) {
 		uprobe_mmap(insert);
+	}
 
 	mas_destroy(&mas);
 	validate_mm(mm);
+
 	return 0;
 }
 
@@ -1218,10 +1116,10 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
 	if (vm_flags & VM_SPECIAL)
 		return NULL;
 
-	next = __vma_next(mm, prev);
+	next = find_vma(mm, prev ? prev->vm_end : 0);
 	area = next;
 	if (area && area->vm_end == end)		/* cases 6, 7, 8 */
-		next = next->vm_next;
+		next = find_vma(mm, next->vm_end);
 
 	/* verify some invariant that must be enforced by the caller */
 	VM_WARN_ON(prev && addr <= prev->vm_start);
@@ -1355,18 +1253,24 @@ static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_
  */
 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
 {
+	MA_STATE(mas, &vma->vm_mm->mm_mt, vma->vm_end, vma->vm_end);
 	struct anon_vma *anon_vma = NULL;
+	struct vm_area_struct *prev, *next;
 
 	/* Try next first. */
-	if (vma->vm_next) {
-		anon_vma = reusable_anon_vma(vma->vm_next, vma, vma->vm_next);
+	next = mas_walk(&mas);
+	if (next) {
+		anon_vma = reusable_anon_vma(next, vma, next);
 		if (anon_vma)
 			return anon_vma;
 	}
 
+	prev = mas_prev(&mas, 0);
+	VM_BUG_ON_VMA(prev != vma, vma);
+	prev = mas_prev(&mas, 0);
 	/* Try prev next. */
-	if (vma->vm_prev)
-		anon_vma = reusable_anon_vma(vma->vm_prev, vma->vm_prev, vma);
+	if (prev)
+		anon_vma = reusable_anon_vma(prev, prev, vma);
 
 	/*
 	 * We might reach here with anon_vma == NULL if we can't find
@@ -2133,8 +2037,8 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
 	if (gap_addr < address || gap_addr > TASK_SIZE)
 		gap_addr = TASK_SIZE;
 
-	next = vma->vm_next;
-	if (next && next->vm_start < gap_addr && vma_is_accessible(next)) {
+	next = find_vma_intersection(mm, vma->vm_end, gap_addr);
+	if (next && vma_is_accessible(next)) {
 		if (!(next->vm_flags & VM_GROWSUP))
 			return -ENOMEM;
 		/* Check that both stack segments have the same anon_vma? */
@@ -2185,8 +2089,6 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
 				/* Overwrite old entry in mtree. */
 				vma_mas_store(vma, &mas);
 				anon_vma_interval_tree_post_update_vma(vma);
-				if (!vma->vm_next)
-					mm->highest_vm_end = vm_end_gap(vma);
 				spin_unlock(&mm->page_table_lock);
 
 				perf_event_mmap(vma);
@@ -2206,16 +2108,16 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
 int expand_downwards(struct vm_area_struct *vma, unsigned long address)
 {
 	struct mm_struct *mm = vma->vm_mm;
+	MA_STATE(mas, &mm->mm_mt, vma->vm_start, vma->vm_start);
 	struct vm_area_struct *prev;
 	int error = 0;
-	MA_STATE(mas, &mm->mm_mt, 0, 0);
 
 	address &= PAGE_MASK;
 	if (address < mmap_min_addr)
 		return -EPERM;
 
 	/* Enforce stack_guard_gap */
-	prev = vma->vm_prev;
+	prev = mas_prev(&mas, 0);
 	/* Check that both stack segments have the same anon_vma? */
 	if (prev && !(prev->vm_flags & VM_GROWSDOWN) &&
 			vma_is_accessible(prev)) {
@@ -2351,25 +2253,26 @@ find_extend_vma(struct mm_struct *mm, unsigned long addr)
 EXPORT_SYMBOL_GPL(find_extend_vma);
 
 /*
- * Ok - we have the memory areas we should free on the vma list,
- * so release them, and do the vma updates.
+ * 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 void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
+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);
-	do {
+	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);
-		vma = remove_vma(vma);
-	} while (vma);
+		remove_vma(vma);
+	}
 	vm_unacct_memory(nr_accounted);
 	validate_mm(mm);
 }
@@ -2379,18 +2282,18 @@ static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
  *
  * Called with the mm semaphore held.
  */
-static void unmap_region(struct mm_struct *mm,
+static void unmap_region(struct mm_struct *mm, struct maple_tree *mt,
 		struct vm_area_struct *vma, struct vm_area_struct *prev,
+		struct vm_area_struct *next,
 		unsigned long start, unsigned long end)
 {
-	struct vm_area_struct *next = __vma_next(mm, prev);
 	struct mmu_gather tlb;
 
 	lru_add_drain();
 	tlb_gather_mmu(&tlb, mm);
 	update_hiwater_rss(mm);
-	unmap_vmas(&tlb, vma, start, end);
-	free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
+	unmap_vmas(&tlb, mt, vma, start, end);
+	free_pgtables(&tlb, mt, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
 				 next ? next->vm_start : USER_PGTABLES_CEILING);
 	tlb_finish_mmu(&tlb);
 }
@@ -2474,24 +2377,17 @@ int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
 	return __split_vma(mm, vma, addr, new_below);
 }
 
-static inline int
-unlock_range(struct vm_area_struct *start, struct vm_area_struct **tail,
-	     unsigned long limit)
+static inline int munmap_sidetree(struct vm_area_struct *vma,
+				   struct ma_state *mas_detach)
 {
-	struct mm_struct *mm = start->vm_mm;
-	struct vm_area_struct *tmp = start;
-	int count = 0;
-
-	while (tmp && tmp->vm_start < limit) {
-		*tail = tmp;
-		count++;
-		if (tmp->vm_flags & VM_LOCKED)
-			mm->locked_vm -= vma_pages(tmp);
+	mas_set_range(mas_detach, vma->vm_start, vma->vm_end - 1);
+	if (mas_store_gfp(mas_detach, vma, GFP_KERNEL))
+		return -ENOMEM;
 
-		tmp = tmp->vm_next;
-	}
+	if (vma->vm_flags & VM_LOCKED)
+		vma->vm_mm->locked_vm -= vma_pages(vma);
 
-	return count;
+	return 0;
 }
 
 /*
@@ -2511,9 +2407,13 @@ do_mas_align_munmap(struct ma_state *mas, struct vm_area_struct *vma,
 		    struct mm_struct *mm, unsigned long start,
 		    unsigned long end, struct list_head *uf, bool downgrade)
 {
-	struct vm_area_struct *prev, *last;
+	struct vm_area_struct *prev, *next = NULL;
+	struct maple_tree mt_detach;
+	int count = 0;
 	int error = -ENOMEM;
-	/* we have start < vma->vm_end  */
+	MA_STATE(mas_detach, &mt_detach, 0, 0);
+	mt_init_flags(&mt_detach, MT_FLAGS_LOCK_EXTERN);
+	mt_set_external_lock(&mt_detach, &mm->mmap_lock);
 
 	if (mas_preallocate(mas, vma, GFP_KERNEL))
 		return -ENOMEM;
@@ -2526,6 +2426,8 @@ do_mas_align_munmap(struct ma_state *mas, struct vm_area_struct *vma,
 	 * 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) {
 
 		/*
@@ -2536,35 +2438,58 @@ do_mas_align_munmap(struct ma_state *mas, struct vm_area_struct *vma,
 		if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
 			goto map_count_exceeded;
 
+		/*
+		 * mas_pause() is not needed since mas->index needs to be set
+		 * differently than vma->vm_end anyways.
+		 */
 		error = __split_vma(mm, vma, start, 0);
 		if (error)
-			goto split_failed;
+			goto start_split_failed;
 
-		prev = vma;
-		vma = __vma_next(mm, prev);
-		mas->index = start;
-		mas_reset(mas);
-	} else {
-		prev = vma->vm_prev;
+		mas_set(mas, start);
+		vma = mas_walk(mas);
 	}
 
-	if (vma->vm_end >= end)
-		last = vma;
-	else
-		last = find_vma_intersection(mm, end - 1, end);
+	prev = mas_prev(mas, 0);
+	if (unlikely((!prev)))
+		mas_set(mas, start);
 
-	/* Does it split the last one? */
-	if (last && end < last->vm_end) {
-		error = __split_vma(mm, last, end, 1);
+	/*
+	 * Detach a range of VMAs from the mm. Using next as a temp variable as
+	 * it is always overwritten.
+	 */
+	mas_for_each(mas, next, end - 1) {
+		/* Does it split the end? */
+		if (next->vm_end > end) {
+			struct vm_area_struct *split;
 
-		if (error)
-			goto split_failed;
+			error = __split_vma(mm, next, end, 1);
+			if (error)
+				goto end_split_failed;
+
+			mas_set(mas, end);
+			split = mas_prev(mas, 0);
+			if (munmap_sidetree(split, &mas_detach))
+				goto munmap_sidetree_failed;
 
-		if (vma == last)
-			vma = __vma_next(mm, prev);
-		mas_reset(mas);
+			count++;
+			if (vma == next)
+				vma = split;
+			break;
+		}
+		if (munmap_sidetree(next, &mas_detach))
+			goto munmap_sidetree_failed;
+
+		count++;
+#ifdef CONFIG_DEBUG_VM_MAPLE_TREE
+		BUG_ON(next->vm_start < start);
+		BUG_ON(next->vm_start > end);
+#endif
 	}
 
+	if (!next)
+		next = mas_next(mas, ULONG_MAX);
+
 	if (unlikely(uf)) {
 		/*
 		 * If userfaultfd_unmap_prep returns an error the vmas
@@ -2581,35 +2506,36 @@ do_mas_align_munmap(struct ma_state *mas, struct vm_area_struct *vma,
 			goto userfaultfd_error;
 	}
 
-	/*
-	 * unlock any mlock()ed ranges before detaching vmas, count the number
-	 * of VMAs to be dropped, and return the tail entry of the affected
-	 * area.
-	 */
-	mm->map_count -= unlock_range(vma, &last, end);
-	/* Drop removed area from the tree */
+	/* Point of no return */
+	mas_set_range(mas, start, end - 1);
+#if defined(CONFIG_DEBUG_VM_MAPLE_TREE)
+	/* Make sure no VMAs are about to be lost. */
+	{
+		MA_STATE(test, &mt_detach, start, end - 1);
+		struct vm_area_struct *vma_mas, *vma_test;
+		int test_count = 0;
+
+		rcu_read_lock();
+		vma_test = mas_find(&test, end - 1);
+		mas_for_each(mas, vma_mas, end - 1) {
+			BUG_ON(vma_mas != vma_test);
+			test_count++;
+			vma_test = mas_next(&test, end - 1);
+		}
+		rcu_read_unlock();
+		BUG_ON(count != test_count);
+		mas_set_range(mas, start, end - 1);
+	}
+#endif
 	mas_store_prealloc(mas, NULL);
-
-	/* Detach vmas from the MM linked list */
-	vma->vm_prev = NULL;
-	if (prev)
-		prev->vm_next = last->vm_next;
-	else
-		mm->mmap = last->vm_next;
-
-	if (last->vm_next) {
-		last->vm_next->vm_prev = prev;
-		last->vm_next = NULL;
-	} else
-		mm->highest_vm_end = prev ? vm_end_gap(prev) : 0;
-
+	mm->map_count -= count;
 	/*
 	 * Do not downgrade mmap_lock if we are next to VM_GROWSDOWN or
 	 * VM_GROWSUP VMA. Such VMAs can change their size under
 	 * down_read(mmap_lock) and collide with the VMA we are about to unmap.
 	 */
 	if (downgrade) {
-		if (last && (last->vm_flags & VM_GROWSDOWN))
+		if (next && (next->vm_flags & VM_GROWSDOWN))
 			downgrade = false;
 		else if (prev && (prev->vm_flags & VM_GROWSUP))
 			downgrade = false;
@@ -2617,18 +2543,22 @@ do_mas_align_munmap(struct ma_state *mas, struct vm_area_struct *vma,
 			mmap_write_downgrade(mm);
 	}
 
-	unmap_region(mm, vma, prev, start, end);
-
-	/* Fix up all other VM information */
-	remove_vma_list(mm, vma);
+	unmap_region(mm, &mt_detach, vma, prev, next, start, end);
+	/* Statistics and freeing VMAs */
+	mas_set(&mas_detach, start);
+	remove_mt(mm, &mas_detach);
+	__mt_destroy(&mt_detach);
 
 
 	validate_mm(mm);
 	return downgrade ? 1 : 0;
 
-map_count_exceeded:
-split_failed:
 userfaultfd_error:
+munmap_sidetree_failed:
+end_split_failed:
+	__mt_destroy(&mt_detach);
+start_split_failed:
+map_count_exceeded:
 	mas_destroy(mas);
 	return error;
 }
@@ -2863,7 +2793,6 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 		i_mmap_lock_write(vma->vm_file->f_mapping);
 
 	vma_mas_store(vma, &mas);
-	__vma_link_list(mm, vma, prev);
 	mm->map_count++;
 	if (vma->vm_file) {
 		if (vma->vm_flags & VM_SHARED)
@@ -2921,7 +2850,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 	vma->vm_file = NULL;
 
 	/* Undo any partial mapping done by a device driver. */
-	unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
+	unmap_region(mm, mas.tree, vma, prev, next, vma->vm_start, vma->vm_end);
 	charged = 0;
 	if (vm_flags & VM_SHARED)
 		mapping_unmap_writable(file->f_mapping);
@@ -3010,11 +2939,12 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
 		goto out;
 
 	if (start + size > vma->vm_end) {
-		struct vm_area_struct *next;
+		VMA_ITERATOR(vmi, mm, vma->vm_end);
+		struct vm_area_struct *next, *prev = vma;
 
-		for (next = vma->vm_next; next; next = next->vm_next) {
+		for_each_vma_range(vmi, next, start + size) {
 			/* hole between vmas ? */
-			if (next->vm_start != next->vm_prev->vm_end)
+			if (next->vm_start != prev->vm_end)
 				goto out;
 
 			if (next->vm_file != vma->vm_file)
@@ -3023,8 +2953,7 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
 			if (next->vm_flags != vma->vm_flags)
 				goto out;
 
-			if (start + size <= next->vm_end)
-				break;
+			prev = next;
 		}
 
 		if (!next)
@@ -3070,7 +2999,7 @@ static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
 			 struct list_head *uf)
 {
 	struct mm_struct *mm = vma->vm_mm;
-	struct vm_area_struct unmap;
+	struct vm_area_struct unmap, *next;
 	unsigned long unmap_pages;
 	int ret;
 
@@ -3086,6 +3015,7 @@ static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
 	ret = userfaultfd_unmap_prep(mm, newbrk, oldbrk, uf);
 	if (ret)
 		return ret;
+
 	ret = 1;
 
 	/* Change the oldbrk of vma to the newbrk of the munmap area */
@@ -3107,6 +3037,7 @@ static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
 
 	vma_mas_remove(&unmap, mas);
 
+	vma->vm_end = newbrk;
 	if (vma->anon_vma) {
 		anon_vma_interval_tree_post_update_vma(vma);
 		anon_vma_unlock_write(vma->anon_vma);
@@ -3116,8 +3047,9 @@ static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
 	if (vma->vm_flags & VM_LOCKED)
 		mm->locked_vm -= unmap_pages;
 
+	next = mas_next(mas, ULONG_MAX);
 	mmap_write_downgrade(mm);
-	unmap_region(mm, &unmap, vma, newbrk, oldbrk);
+	unmap_region(mm, mas->tree, &unmap, vma, next, newbrk, oldbrk);
 	/* Statistics */
 	vm_stat_account(mm, vma->vm_flags, -unmap_pages);
 	if (vma->vm_flags & VM_ACCOUNT)
@@ -3141,11 +3073,9 @@ static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
  * do some brk-specific accounting here.
  */
 static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
-			unsigned long addr, unsigned long len,
-			unsigned long flags)
+		unsigned long addr, unsigned long len, unsigned long flags)
 {
 	struct mm_struct *mm = current->mm;
-	struct vm_area_struct *prev = NULL;
 	validate_mm_mt(mm);
 
 
@@ -3189,7 +3119,6 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
 		khugepaged_enter_vma(vma, flags);
 		goto out;
 	}
-	prev = vma;
 
 	/* create a vma struct for an anonymous mapping */
 	vma = vm_area_alloc(mm);
@@ -3207,12 +3136,6 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
 		goto mas_store_fail;
 
 	mm->map_count++;
-
-	if (!prev)
-		prev = mas_prev(mas, 0);
-
-	__vma_link_list(mm, vma, prev);
-	mm->map_count++;
 out:
 	perf_event_mmap(vma);
 	mm->total_vm += len >> PAGE_SHIFT;
@@ -3220,7 +3143,7 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
 	if (flags & VM_LOCKED)
 		mm->locked_vm += (len >> PAGE_SHIFT);
 	vma->vm_flags |= VM_SOFTDIRTY;
-	validate_mm_mt(mm);
+	validate_mm(mm);
 	return 0;
 
 mas_store_fail:
@@ -3294,6 +3217,8 @@ void exit_mmap(struct mm_struct *mm)
 	struct mmu_gather tlb;
 	struct vm_area_struct *vma;
 	unsigned long nr_accounted = 0;
+	MA_STATE(mas, &mm->mm_mt, 0, 0);
+	int count = 0;
 
 	/* mm's last user has gone, and its about to be pulled down */
 	mmu_notifier_release(mm);
@@ -3318,7 +3243,7 @@ void exit_mmap(struct mm_struct *mm)
 	mmap_write_lock(mm);
 	arch_exit_mmap(mm);
 
-	vma = mm->mmap;
+	vma = mas_find(&mas, ULONG_MAX);
 	if (!vma) {
 		/* Can happen if dup_mmap() received an OOM */
 		mmap_write_unlock(mm);
@@ -3329,22 +3254,29 @@ void exit_mmap(struct mm_struct *mm)
 	flush_cache_mm(mm);
 	tlb_gather_mmu_fullmm(&tlb, mm);
 	/* update_hiwater_rss(mm) here? but nobody should be looking */
-	/* Use -1 here to ensure all VMAs in the mm are unmapped */
-	unmap_vmas(&tlb, vma, 0, -1);
-	free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
+	/* Use ULONG_MAX here to ensure all VMAs in the mm are unmapped */
+	unmap_vmas(&tlb, &mm->mm_mt, vma, 0, ULONG_MAX);
+	free_pgtables(&tlb, &mm->mm_mt, vma, FIRST_USER_ADDRESS,
+		      USER_PGTABLES_CEILING);
 	tlb_finish_mmu(&tlb);
 
-	/* Walk the list again, actually closing and freeing it. */
-	while (vma) {
+	/*
+	 * Walk the list again, actually closing and freeing it, with preemption
+	 * enabled, without holding any MM locks besides the unreachable
+	 * mmap_write_lock.
+	 */
+	do {
 		if (vma->vm_flags & VM_ACCOUNT)
 			nr_accounted += vma_pages(vma);
-		vma = remove_vma(vma);
+		remove_vma(vma);
+		count++;
 		cond_resched();
-	}
+	} while ((vma = mas_find(&mas, ULONG_MAX)) != NULL);
+
+	BUG_ON(count != mm->map_count);
 
 	trace_exit_mmap(mm);
 	__mt_destroy(&mm->mm_mt);
-	mm->mmap = NULL;
 	mmap_write_unlock(mm);
 	vm_unacct_memory(nr_accounted);
 }
@@ -3381,7 +3313,7 @@ int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
 		vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
 	}
 
-	if (vma_link(mm, vma, prev))
+	if (vma_link(mm, vma))
 		return -ENOMEM;
 
 	return 0;
@@ -3411,7 +3343,8 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
 		faulted_in_anon_vma = false;
 	}
 
-	if (range_has_overlap(mm, addr, addr + len, &prev))
+	new_vma = find_vma_prev(mm, addr, &prev);
+	if (new_vma->vm_start < addr + len)
 		return NULL;	/* should never get here */
 
 	new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
@@ -3454,7 +3387,7 @@ 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);
-		if (vma_link(mm, new_vma, prev))
+		if (vma_link(mm, new_vma))
 			goto out_vma_link;
 		*need_rmap_locks = false;
 	}
@@ -3759,12 +3692,13 @@ int mm_take_all_locks(struct mm_struct *mm)
 {
 	struct vm_area_struct *vma;
 	struct anon_vma_chain *avc;
+	MA_STATE(mas, &mm->mm_mt, 0, 0);
 
 	mmap_assert_write_locked(mm);
 
 	mutex_lock(&mm_all_locks_mutex);
 
-	for (vma = mm->mmap; vma; vma = vma->vm_next) {
+	mas_for_each(&mas, vma, ULONG_MAX) {
 		if (signal_pending(current))
 			goto out_unlock;
 		if (vma->vm_file && vma->vm_file->f_mapping &&
@@ -3772,7 +3706,8 @@ int mm_take_all_locks(struct mm_struct *mm)
 			vm_lock_mapping(mm, vma->vm_file->f_mapping);
 	}
 
-	for (vma = mm->mmap; vma; vma = vma->vm_next) {
+	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 &&
@@ -3780,7 +3715,8 @@ int mm_take_all_locks(struct mm_struct *mm)
 			vm_lock_mapping(mm, vma->vm_file->f_mapping);
 	}
 
-	for (vma = mm->mmap; vma; vma = vma->vm_next) {
+	mas_set(&mas, 0);
+	mas_for_each(&mas, vma, ULONG_MAX) {
 		if (signal_pending(current))
 			goto out_unlock;
 		if (vma->anon_vma)
@@ -3839,11 +3775,12 @@ void mm_drop_all_locks(struct mm_struct *mm)
 {
 	struct vm_area_struct *vma;
 	struct anon_vma_chain *avc;
+	MA_STATE(mas, &mm->mm_mt, 0, 0);
 
 	mmap_assert_write_locked(mm);
 	BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
 
-	for (vma = mm->mmap; vma; vma = vma->vm_next) {
+	mas_for_each(&mas, vma, ULONG_MAX) {
 		if (vma->anon_vma)
 			list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
 				vm_unlock_anon_vma(avc->anon_vma);
diff --git a/mm/nommu.c b/mm/nommu.c
index f6b187090d95..7b3fad611895 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -584,17 +584,12 @@ static void setup_vma_to_mm(struct vm_area_struct *vma, struct mm_struct *mm)
 static void mas_add_vma_to_mm(struct ma_state *mas, struct mm_struct *mm,
 			      struct vm_area_struct *vma)
 {
-	struct vm_area_struct *prev;
-
 	BUG_ON(!vma->vm_region);
 
 	setup_vma_to_mm(vma, mm);
 
-	prev = mas_prev(mas, 0);
-	mas_reset(mas);
 	/* add the VMA to the tree */
 	vma_mas_store(vma, mas);
-	__vma_link_list(mm, vma, prev);
 }
 
 /*
@@ -647,7 +642,6 @@ static int delete_vma_from_mm(struct vm_area_struct *vma)
 
 	/* remove from the MM's tree and list */
 	vma_mas_remove(vma, &mas);
-	__vma_unlink_list(vma->vm_mm, vma);
 	return 0;
 }
 
diff --git a/mm/util.c b/mm/util.c
index 2ffc32294a97..331bc94423c0 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -272,46 +272,6 @@ void *memdup_user_nul(const void __user *src, size_t len)
 }
 EXPORT_SYMBOL(memdup_user_nul);
 
-void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
-		struct vm_area_struct *prev)
-{
-	struct vm_area_struct *next;
-
-	vma->vm_prev = prev;
-	if (prev) {
-		next = prev->vm_next;
-		prev->vm_next = vma;
-	} else {
-		next = mm->mmap;
-		mm->mmap = vma;
-	}
-	vma->vm_next = next;
-	if (next)
-		next->vm_prev = vma;
-	else
-		mm->highest_vm_end = vm_end_gap(vma);
-}
-
-void __vma_unlink_list(struct mm_struct *mm, struct vm_area_struct *vma)
-{
-	struct vm_area_struct *prev, *next;
-
-	next = vma->vm_next;
-	prev = vma->vm_prev;
-	if (prev)
-		prev->vm_next = next;
-	else
-		mm->mmap = next;
-	if (next) {
-		next->vm_prev = prev;
-	} else {
-		if (prev)
-			mm->highest_vm_end = vm_end_gap(prev);
-		else
-			mm->highest_vm_end = 0;
-	}
-}
-
 /* Check if the vma is being used as a stack by this task */
 int vma_is_stack_for_current(struct vm_area_struct *vma)
 {
-- 
2.35.1
