mm/init-mm, mm/mmap, kernel/fork: Start tracking VMAs with maple tree

Start tracking the VMAs with the new maple tree structure in parallel
with the rb_tree.  Add debug and trace events for maple tree operations
and duplicate the rb_tree that is created on forks into the maple tree.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

diff --git a/include/linux/mm.h b/include/linux/mm.h
index dc7b87310c1035c3e1cc02305e09d31fae7e2fb0..bbfb5cf28a7279ad156b4b64ab538fb8c6aafb80 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2472,6 +2472,8 @@ extern bool arch_has_descending_max_zone_pfns(void);
 /* nommu.c */
 extern atomic_long_t mmap_pages_allocated;
 extern int nommu_shrink_inode_mappings(struct inode *, size_t, size_t);
+/* maple_tree */
+void vma_store(struct mm_struct *mm, struct vm_area_struct *vma);
 
 /* interval_tree.c */
 void vma_interval_tree_insert(struct vm_area_struct *node,

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 64ede5f150dc5396c5877d8f1f1fa786a0b89e5d..90021d0c053095e450355d022e5b683f910d39fa 100644 (file)
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -8,6 +8,7 @@
 #include <linux/list.h>
 #include <linux/spinlock.h>
 #include <linux/rbtree.h>
+#include <linux/maple_tree.h>
 #include <linux/rwsem.h>
 #include <linux/completion.h>
 #include <linux/cpumask.h>
@@ -384,6 +385,7 @@ struct kioctx_table;
 struct mm_struct {
        struct {
                struct vm_area_struct *mmap;            /* list of VMAs */
+               struct maple_tree mm_mt;
                struct rb_root mm_rb;
                u64 vmacache_seqnum;                   /* per-thread vmacache */
 #ifdef CONFIG_MMU

diff --git a/include/trace/events/mm_mt.h b/include/trace/events/mm_mt.h
new file mode 100644 (file)
index 0000000..0daa69a
--- /dev/null
+++ b/include/trace/events/mm_mt.h
@@ -0,0 +1,125 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM mm_mt
+
+#if !defined(_TRACE_MM_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_MM_H
+
+
+#include <linux/tracepoint.h>
+
+struct mm_struct;
+struct vm_area_struct;
+
+/**
+ * vma_mt_erase - called to erase an entry from the mm_mt
+ *
+ * @mm:                the mm_struct which contains the mt
+ * @vma:       the vma that is to be erased.
+ *
+ */
+TRACE_EVENT(vma_mt_erase,
+
+       TP_PROTO(struct mm_struct *mm, struct vm_area_struct *vma),
+
+       TP_ARGS(mm, vma),
+
+       TP_STRUCT__entry(
+                       __field(struct mm_struct *, mm)
+                       __field(struct vm_area_struct *, vma)
+                       __field(unsigned long, vm_start)
+                       __field(unsigned long, vm_end)
+       ),
+
+       TP_fast_assign(
+                       __entry->mm             = mm;
+                       __entry->vma            = vma;
+                       __entry->vm_start       = vma->vm_start;
+                       __entry->vm_end         = vma->vm_end - 1;
+       ),
+
+       TP_printk("mt_mod %p, (%p), ERASE, %lu, %lu",
+                 __entry->mm, __entry->vma,
+                 (unsigned long) __entry->vm_start,
+                 (unsigned long) __entry->vm_end
+       )
+);
+
+/**
+ * vma_mt_szero - Called to set a range to NULL in the mm_mt
+ *
+ */
+TRACE_EVENT(vma_mt_szero,
+       TP_PROTO(struct mm_struct *mm, unsigned long start,
+                unsigned long end),
+
+       TP_ARGS(mm, start, end),
+
+       TP_STRUCT__entry(
+                       __field(struct mm_struct*, mm)
+                       __field(unsigned long, start)
+                       __field(unsigned long, end)
+       ),
+
+       TP_fast_assign(
+                       __entry->mm             = mm;
+                       __entry->start          = start;
+                       __entry->end            = end - 1;
+       ),
+
+       TP_printk("mt_mod %p, (NULL), SNULL, %lu, %lu",
+                 __entry->mm,
+                 (unsigned long) __entry->start,
+                 (unsigned long) __entry->end
+       )
+);
+
+TRACE_EVENT(vma_mt_store,
+       TP_PROTO(struct mm_struct *mm, struct vm_area_struct *vma),
+
+       TP_ARGS(mm, vma),
+
+       TP_STRUCT__entry(
+                       __field(struct mm_struct*, mm)
+                       __field(struct vm_area_struct*, vma)
+                       __field(unsigned long, vm_start)
+                       __field(unsigned long, vm_end)
+       ),
+
+       TP_fast_assign(
+                       __entry->mm             = mm;
+                       __entry->vma            = vma;
+                       __entry->vm_start       = vma->vm_start;
+                       __entry->vm_end         = vma->vm_end - 1;
+       ),
+
+       TP_printk("mt_mod %p, (%p), STORE, %lu, %lu",
+                 __entry->mm, __entry->vma,
+                 (unsigned long) __entry->vm_start,
+                 (unsigned long) __entry->vm_end - 1
+       )
+);
+
+
+TRACE_EVENT(exit_mmap,
+       TP_PROTO(struct mm_struct *mm),
+
+       TP_ARGS(mm),
+
+       TP_STRUCT__entry(
+                       __field(struct mm_struct*, mm)
+       ),
+
+       TP_fast_assign(
+                       __entry->mm             = mm;
+       ),
+
+       TP_printk("mt_mod %p, DESTROY\n",
+                 __entry->mm
+       )
+);
+
+#endif /* _TRACE_MM_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>

diff --git a/kernel/fork.c b/kernel/fork.c
index efc5493203ae0b744d0684ec10f531bb5c7b9557..8b38eebf7e106f390e7a195469b1c9ed723d0e8b 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -604,6 +604,9 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
                rb_link = &tmp->vm_rb.rb_right;
                rb_parent = &tmp->vm_rb;
 
+               /* Link the vma into the MT */
+               vma_store(mm, tmp);
+
                mm->map_count++;
                if (!(tmp->vm_flags & VM_WIPEONFORK))
                        retval = copy_page_range(mm, oldmm, mpnt);
@@ -1019,6 +1022,7 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
 {
        mm->mmap = NULL;
        mm->mm_rb = RB_ROOT;
+       mt_init_flags(&mm->mm_mt, MAPLE_ALLOC_RANGE);
        mm->vmacache_seqnum = 0;
        atomic_set(&mm->mm_users, 1);
        atomic_set(&mm->mm_count, 1);

diff --git a/mm/init-mm.c b/mm/init-mm.c
index 3a613c85f9ede21e197ec7cf00d249b4085d4df4..27229044a070211f08e930c1070d8a6cc6d26572 100644 (file)
--- a/mm/init-mm.c
+++ b/mm/init-mm.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <linux/mm_types.h>
 #include <linux/rbtree.h>
+#include <linux/maple_tree.h>
 #include <linux/rwsem.h>
 #include <linux/spinlock.h>
 #include <linux/list.h>
@@ -28,6 +29,7 @@
  */
 struct mm_struct init_mm = {
        .mm_rb          = RB_ROOT,
+       .mm_mt          = MTREE_INIT(mm_mt, MAPLE_ALLOC_RANGE),
        .pgd            = swapper_pg_dir,
        .mm_users       = ATOMIC_INIT(2),
        .mm_count       = ATOMIC_INIT(1),

diff --git a/mm/mmap.c b/mm/mmap.c
index 7c442fd04c189aa395ef50b265be2df98f5cdb0a..3e786a44a7f4a748253c2978a3d0d5258d22e753 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -57,6 +57,9 @@
 #include <trace/events/mmap.h>
 
 #include "internal.h"
+#define CREATE_TRACE_POINTS
+#include <trace/events/mm_mt.h>
+extern void mt_validate(struct maple_tree *mt);
 
 #ifndef arch_mmap_check
 #define arch_mmap_check(addr, len, flags)      (0)
@@ -373,7 +376,70 @@ static int browse_rb(struct mm_struct *mm)
        }
        return bug ? -1 : i;
 }
+#if defined(CONFIG_DEBUG_MAPLE_TREE)
+extern void mt_dump(const struct maple_tree *mt);
+
+/* Validate the maple tree */
+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;
 
+       MA_STATE(mas, mt, 0, 0);
+       rcu_read_lock();
+       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)) {
+                       pr_emerg("issue in %s\n", current->comm);
+                       dump_stack();
+#ifdef CONFIG_DEBUG_VM
+                       dump_vma(vma_mt);
+                       pr_emerg("and next in rb\n");
+                       dump_vma(vma->vm_next);
+#endif
+                       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);
+                       pr_emerg("rb vma: %px %lu - %lu\n", vma,
+                                vma->vm_start, vma->vm_end);
+                       pr_emerg("rb->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) {
+                               pr_err("vma: %px vma_mt %lu-%lu\tmt %lu-%lu\n",
+                                               mm, vma_mt->vm_start, vma_mt->vm_end,
+                                               mas.index, mas.last);
+                               mt_dump(mas.tree);
+                       }
+                       VM_BUG_ON_MM(vma_mt->vm_end != mas.last + 1, mm);
+                       if (vma_mt->vm_start != mas.index) {
+                               pr_err("vma: %px vma_mt %px %lu - %lu doesn't match\n",
+                                               mm, vma_mt, vma_mt->vm_start, vma_mt->vm_end);
+                               mt_dump(mas.tree);
+                       }
+                       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);
+
+       rcu_read_unlock();
+       mt_validate(&mm->mm_mt);
+}
+#endif
 static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore)
 {
        struct rb_node *nd;
@@ -428,6 +494,7 @@ static void validate_mm(struct mm_struct *mm)
 }
 #else
 #define validate_mm_rb(root, ignore) do { } while (0)
+#define validate_mm_mt(root) do { } while (0)
 #define validate_mm(mm) do { } while (0)
 #endif
 
@@ -609,6 +676,7 @@ static unsigned long count_vma_pages_range(struct mm_struct *mm,
                unsigned long addr, unsigned long end)
 {
        unsigned long nr_pages = 0;
+       unsigned long nr_mt_pages = 0;
        struct vm_area_struct *vma;
 
        /* Find first overlaping mapping */
@@ -630,6 +698,13 @@ static unsigned long count_vma_pages_range(struct mm_struct *mm,
                nr_pages += overlap_len >> PAGE_SHIFT;
        }
 
+       mt_for_each(&mm->mm_mt, vma, addr, end) {
+               nr_mt_pages +=
+                       (min(end, vma->vm_end) - vma->vm_start) >> PAGE_SHIFT;
+       }
+
+       VM_BUG_ON_MM(nr_pages != nr_mt_pages, mm);
+
        return nr_pages;
 }
 
@@ -675,12 +750,59 @@ static void __vma_link_file(struct vm_area_struct *vma)
                flush_dcache_mmap_unlock(mapping);
        }
 }
+/* Private
+ * vma_mt_erase() - erase a VMA entry from the maple tree.
+ *
+ * @mm: The struct_mm
+ * @vma: The vm_area_struct to erase from the maple tree.
+ */
+static inline void vma_mt_erase(struct mm_struct *mm, struct vm_area_struct *vma)
+{
+       trace_vma_mt_erase(mm, vma);
+       mtree_erase(&mm->mm_mt, vma->vm_start);
+}
+/* Private
+ * vma_mt_szero() - Set a given range to zero.  Used when modifying a
+ * vm_area_struct start or end.
+ *
+ * @mm: The struct_mm
+ * @start: The start address to zero
+ * @end: The end address to zero.
+ */
+static inline void vma_mt_szero(struct mm_struct *mm, unsigned long start,
+               unsigned long end)
+{
+       trace_vma_mt_szero(mm, start, end);
+       mtree_store_range(&mm->mm_mt, start, end - 1, NULL, GFP_KERNEL);
+}
+/* Private
+ * vma_mt_store() - Store a given vm_area_struct in the maple tree.
+ *
+ * @mm: The struct_mm
+ * @vma: The vm_area_struct to store in the maple tree.
+ */
+static inline void vma_mt_store(struct mm_struct *mm, struct vm_area_struct *vma)
+{
+       trace_vma_mt_store(mm, vma);
+       mtree_store_range(&mm->mm_mt, vma->vm_start, vma->vm_end - 1, vma,
+               GFP_KERNEL);
+}
+/* External interface to store a vma into an @mm.  Used in fork.
+ *
+ * @mm: The struct_mm
+ * @vma: The vm_area_struct to store in the maple tree.
+ */
+void vma_store(struct mm_struct *mm, struct vm_area_struct *vma)
+{
+       vma_mt_store(mm, vma);
+}
 
 static void
 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
        struct vm_area_struct *prev, struct rb_node **rb_link,
        struct rb_node *rb_parent)
 {
+       vma_mt_store(mm, vma);
        __vma_link_list(mm, vma, prev);
        __vma_link_rb(mm, vma, rb_link, rb_parent);
 }
@@ -753,6 +875,9 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
        long adjust_next = 0;
        int remove_next = 0;
 
+       validate_mm(mm);
+       validate_mm_mt(mm);
+
        if (next && !insert) {
                struct vm_area_struct *exporter = NULL, *importer = NULL;
 
@@ -878,17 +1003,31 @@ again:
        }
 
        if (start != vma->vm_start) {
+               unsigned long old_start = vma->vm_start;
                vma->vm_start = start;
+               if (old_start < start)
+                       vma_mt_szero(mm, old_start, start);
                start_changed = true;
        }
        if (end != vma->vm_end) {
+               unsigned long old_end = vma->vm_end;
                vma->vm_end = end;
+               if (old_end > end)
+                       vma_mt_szero(mm, end - 1, old_end);
                end_changed = true;
        }
+
+       if (end_changed || start_changed)
+               vma_mt_store(mm, vma);
+
        vma->vm_pgoff = pgoff;
        if (adjust_next) {
                next->vm_start += adjust_next << PAGE_SHIFT;
                next->vm_pgoff += adjust_next;
+               /* the vma_store is necessary as the adjust_next may be
+                * negative and expand backwards.
+                */
+               vma_mt_store(mm, next);
        }
 
        if (root) {
@@ -902,6 +1041,8 @@ again:
                /*
                 * vma_merge has merged next into vma, and needs
                 * us to remove next before dropping the locks.
+                * Since we have expanded over this vma, the maple tree will
+                * have overwritten by storing the value
                 */
                if (remove_next != 3)
                        __vma_unlink_common(mm, next, next);
@@ -1022,6 +1163,7 @@ again:
                uprobe_mmap(insert);
 
        validate_mm(mm);
+       validate_mm_mt(mm);
 
        return 0;
 }
@@ -1169,6 +1311,7 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
        struct vm_area_struct *area, *next;
        int err;
 
+       validate_mm_mt(mm);
        /*
         * We later require that vma->vm_flags == vm_flags,
         * so this tests vma->vm_flags & VM_SPECIAL, too.
@@ -1244,6 +1387,7 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
                khugepaged_enter_vma_merge(area, vm_flags);
                return area;
        }
+       validate_mm_mt(mm);
 
        return NULL;
 }
@@ -1736,6 +1880,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
        struct rb_node **rb_link, *rb_parent;
        unsigned long charged = 0;
 
+       validate_mm_mt(mm);
        /* Check against address space limit. */
        if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) {
                unsigned long nr_pages;
@@ -1866,6 +2011,7 @@ out:
 
        vma_set_page_prot(vma);
 
+       validate_mm_mt(mm);
        return addr;
 
 unmap_and_free_vma:
@@ -1885,6 +2031,7 @@ free_vma:
 unacct_error:
        if (charged)
                vm_unacct_memory(charged);
+       validate_mm_mt(mm);
        return error;
 }
 
@@ -1901,12 +2048,24 @@ static unsigned long unmapped_area(struct vm_unmapped_area_info *info)
        struct mm_struct *mm = current->mm;
        struct vm_area_struct *vma;
        unsigned long length, low_limit, high_limit, gap_start, gap_end;
+       unsigned long gap;
 
+       MA_STATE(mas, &mm->mm_mt, 0, 0);
        /* Adjust search length to account for worst case alignment overhead */
        length = info->length + info->align_mask;
        if (length < info->length)
                return -ENOMEM;
 
+
+       /* Maple tree is self contained. */
+       rcu_read_lock();
+       if (mas_get_unmapped_area(&mas, info->low_limit,
+                               info->high_limit - 1, length))
+               return -ENOMEM;
+       rcu_read_unlock();
+       gap = mas.index;
+       gap += (info->align_offset - gap) & info->align_mask;
+
        /* Adjust search limits by the desired length */
        if (info->high_limit < length)
                return -ENOMEM;
@@ -1988,20 +2147,33 @@ found:
 
        VM_BUG_ON(gap_start + info->length > info->high_limit);
        VM_BUG_ON(gap_start + info->length > gap_end);
+
+       VM_BUG_ON(gap != gap_start);
        return gap_start;
 }
 
 static unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
 {
        struct mm_struct *mm = current->mm;
-       struct vm_area_struct *vma;
+       struct vm_area_struct *vma = NULL;
        unsigned long length, low_limit, high_limit, gap_start, gap_end;
+       unsigned long gap;
 
+       MA_STATE(mas, &mm->mm_mt, 0, 0);
+       validate_mm_mt(mm);
        /* Adjust search length to account for worst case alignment overhead */
        length = info->length + info->align_mask;
        if (length < info->length)
                return -ENOMEM;
 
+       rcu_read_lock();
+       if (mas_get_unmapped_area_rev(&mas, info->low_limit, info->high_limit,
+                               length))
+               return -ENOMEM;
+
+       rcu_read_unlock();
+       gap = (mas.index + info->align_mask) & ~info->align_mask;
+       gap -= info->align_offset & info->align_mask;
        /*
         * Adjust search limits by the desired length.
         * See implementation comment at top of unmapped_area().
@@ -2087,6 +2259,32 @@ found_highest:
 
        VM_BUG_ON(gap_end < info->low_limit);
        VM_BUG_ON(gap_end < gap_start);
+
+       if (gap != gap_end) {
+               pr_err("%s: %px Gap was found: mt %lu gap_end %lu\n", __func__,
+                               mm, gap, gap_end);
+               pr_err("window was %lu - %lu size %lu\n", info->high_limit,
+                               info->low_limit, length);
+               pr_err("mas.min %lu max %lu mas.last %lu\n", mas.min, mas.max,
+                               mas.last);
+               pr_err("mas.index %lu align mask %lu offset %lu\n", mas.index,
+                               info->align_mask, info->align_offset);
+               pr_err("rb_find_vma find on %lu => %px (%px)\n", mas.index,
+                               find_vma(mm, mas.index), vma);
+#if defined(CONFIG_DEBUG_MAPLE_TREE)
+               mt_dump(&mm->mm_mt);
+#endif
+               {
+                       struct vm_area_struct *dv = mm->mmap;
+
+                       while (dv) {
+                               printk("vma %px %lu-%lu\n", dv, dv->vm_start, dv->vm_end);
+                               dv = dv->vm_next;
+                       }
+               }
+               VM_BUG_ON(gap != gap_end);
+       }
+
        return gap_end;
 }
 
@@ -2299,7 +2497,6 @@ struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
                vmacache_update(addr, vma);
        return vma;
 }
-
 EXPORT_SYMBOL(find_vma);
 
 /*
@@ -2380,6 +2577,7 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
        unsigned long gap_addr;
        int error = 0;
 
+       validate_mm_mt(mm);
        if (!(vma->vm_flags & VM_GROWSUP))
                return -EFAULT;
 
@@ -2456,6 +2654,7 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
        anon_vma_unlock_write(vma->anon_vma);
        khugepaged_enter_vma_merge(vma, vma->vm_flags);
        validate_mm(mm);
+       validate_mm_mt(mm);
        return error;
 }
 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
@@ -2470,6 +2669,7 @@ int expand_downwards(struct vm_area_struct *vma,
        struct vm_area_struct *prev;
        int error = 0;
 
+       validate_mm(mm);
        address &= PAGE_MASK;
        if (address < mmap_min_addr)
                return -EPERM;
@@ -2523,6 +2723,8 @@ int expand_downwards(struct vm_area_struct *vma,
                                anon_vma_interval_tree_pre_update_vma(vma);
                                vma->vm_start = address;
                                vma->vm_pgoff -= grow;
+                               /* Overwrite old entry in mtree. */
+                               vma_mt_store(mm, vma);
                                anon_vma_interval_tree_post_update_vma(vma);
                                vma_gap_update(vma);
                                spin_unlock(&mm->page_table_lock);
@@ -2669,6 +2871,7 @@ detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
        vma->vm_prev = NULL;
        do {
                vma_rb_erase(vma, &mm->mm_rb);
+               vma_mt_erase(mm, vma);
                mm->map_count--;
                tail_vma = vma;
                vma = vma->vm_next;
@@ -2694,6 +2897,7 @@ int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
 {
        struct vm_area_struct *new;
        int err;
+       validate_mm_mt(mm);
 
        if (vma->vm_ops && vma->vm_ops->split) {
                err = vma->vm_ops->split(vma, addr);
@@ -2746,6 +2950,7 @@ int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
        mpol_put(vma_policy(new));
  out_free_vma:
        vm_area_free(new);
+       validate_mm_mt(mm);
        return err;
 }
 
@@ -3033,6 +3238,7 @@ static int do_brk_flags(unsigned long addr, unsigned long len, unsigned long fla
        pgoff_t pgoff = addr >> PAGE_SHIFT;
        int error;
        unsigned long mapped_addr;
+       validate_mm_mt(mm);
 
        /* Until we need other flags, refuse anything except VM_EXEC. */
        if ((flags & (~VM_EXEC)) != 0)
@@ -3090,6 +3296,7 @@ out:
        if (flags & VM_LOCKED)
                mm->locked_vm += (len >> PAGE_SHIFT);
        vma->vm_flags |= VM_SOFTDIRTY;
+       validate_mm_mt(mm);
        return 0;
 }
 
@@ -3193,6 +3400,9 @@ void exit_mmap(struct mm_struct *mm)
                        nr_accounted += vma_pages(vma);
                vma = remove_vma(vma);
        }
+
+       trace_exit_mmap(mm);
+       mtree_destroy(&mm->mm_mt);
        vm_unacct_memory(nr_accounted);
 }
 
@@ -3204,10 +3414,25 @@ int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
 {
        struct vm_area_struct *prev;
        struct rb_node **rb_link, *rb_parent;
+       unsigned long start = vma->vm_start;
+       struct vm_area_struct *overlap = NULL;
 
        if (find_vma_links(mm, vma->vm_start, vma->vm_end,
                           &prev, &rb_link, &rb_parent))
                return -ENOMEM;
+
+       overlap = mt_find(&mm->mm_mt, &start, vma->vm_end - 1);
+       if (overlap) {
+
+               pr_err("Found vma ending at %lu\n", start - 1);
+               pr_err("vma : %lu => %lu-%lu\n", (unsigned long)overlap,
+                               overlap->vm_start, overlap->vm_end - 1);
+#if defined(CONFIG_DEBUG_MAPLE_TREE)
+               mt_dump(&mm->mm_mt);
+#endif
+               BUG();
+       }
+
        if ((vma->vm_flags & VM_ACCOUNT) &&
             security_vm_enough_memory_mm(mm, vma_pages(vma)))
                return -ENOMEM;
@@ -3247,7 +3472,9 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
        struct vm_area_struct *new_vma, *prev;
        struct rb_node **rb_link, *rb_parent;
        bool faulted_in_anon_vma = true;
+       unsigned long index = addr;
 
+       validate_mm_mt(mm);
        /*
         * If anonymous vma has not yet been faulted, update new pgoff
         * to match new location, to increase its chance of merging.
@@ -3259,6 +3486,8 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
 
        if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent))
                return NULL;    /* should never get here */
+       if (mt_find(&mm->mm_mt, &index, addr+len - 1))
+               BUG();
        new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
                            vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
                            vma->vm_userfaultfd_ctx);
@@ -3302,6 +3531,7 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
                vma_link(mm, new_vma, prev, rb_link, rb_parent);
                *need_rmap_locks = false;
        }
+       validate_mm_mt(mm);
        return new_vma;
 
 out_free_mempol:
@@ -3309,6 +3539,7 @@ out_free_mempol:
 out_free_vma:
        vm_area_free(new_vma);
 out:
+       validate_mm_mt(mm);
        return NULL;
 }
 
@@ -3433,6 +3664,7 @@ static struct vm_area_struct *__install_special_mapping(
        int ret;
        struct vm_area_struct *vma;
 
+       validate_mm_mt(mm);
        vma = vm_area_alloc(mm);
        if (unlikely(vma == NULL))
                return ERR_PTR(-ENOMEM);
@@ -3454,10 +3686,12 @@ static struct vm_area_struct *__install_special_mapping(
 
        perf_event_mmap(vma);
 
+       validate_mm_mt(mm);
        return vma;
 
 out:
        vm_area_free(vma);
+       validate_mm_mt(mm);
        return ERR_PTR(ret);
 }