Use the maple tree iterator to duplicate the mm_struct trees.

Signed-off-by: Liam R. Howlett <redacted>
---
 include/linux/mm.h       |  2 --
 include/linux/sched/mm.h |  3 +++
 kernel/fork.c            | 24 +++++++++++++++++++-----
 mm/mmap.c                |  4 ----
 4 files changed, 22 insertions(+), 11 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index e89bacfa9145..7f7dff6ad884 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h

@@ -2498,8 +2498,6 @@ 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/sched/mm.h b/include/linux/sched/mm.h
index e24b1fe348e3..76cab3aea6ab 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h

@@ -8,6 +8,7 @@
 #include <linux/mm_types.h>
 #include <linux/gfp.h>
 #include <linux/sync_core.h>
+#include <linux/maple_tree.h>

 /*
  * Routines for handling mm_structs

@@ -67,11 +68,13 @@ static inline void mmdrop(struct mm_struct *mm)
  */
 static inline void mmget(struct mm_struct *mm)
 {
+       mt_set_in_rcu(&mm->mm_mt);
        atomic_inc(&mm->mm_users);
 }

 static inline bool mmget_not_zero(struct mm_struct *mm)
 {
+       mt_set_in_rcu(&mm->mm_mt);

        return atomic_inc_not_zero(&mm->mm_users);
 }

diff --git a/kernel/fork.c b/kernel/fork.c
index c37abaf28eb9..832416ff613e 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c

@@ -477,7 +477,9 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
        struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
        struct rb_node **rb_link, *rb_parent;
        int retval;
-       unsigned long charge;
+       unsigned long charge = 0;
+       MA_STATE(old_mas, &oldmm->mm_mt, 0, 0);
+       MA_STATE(mas, &mm->mm_mt, 0, 0);
        LIST_HEAD(uf);

        uprobe_start_dup_mmap();

@@ -511,7 +513,13 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
                goto out;

        prev = NULL;
-       for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
+
+       retval = mas_entry_count(&mas, oldmm->map_count);
+       if (retval)
+               goto fail_nomem;
+
+       rcu_read_lock();
+       mas_for_each(&old_mas, mpnt, ULONG_MAX) {
                struct file *file;

                if (mpnt->vm_flags & VM_DONTCOPY) {

@@ -525,7 +533,7 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
                 */
                if (fatal_signal_pending(current)) {
                        retval = -EINTR;
-                       goto out;
+                       goto loop_out;
                }
                if (mpnt->vm_flags & VM_ACCOUNT) {
                        unsigned long len = vma_pages(mpnt);

@@ -594,7 +602,9 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
                rb_parent = &tmp->vm_rb;

                /* Link the vma into the MT */
-               vma_store(mm, tmp);
+               mas.index = tmp->vm_start;
+               mas.last = tmp->vm_end - 1;
+               mas_store(&mas, tmp);

                mm->map_count++;
                if (!(tmp->vm_flags & VM_WIPEONFORK))

@@ -604,14 +614,17 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
                        tmp->vm_ops->open(tmp);

                if (retval)
-                       goto out;
+                       goto loop_out;
        }
        /* a new mm has just been created */
        retval = arch_dup_mmap(oldmm, mm);
+loop_out:
 out:
+       rcu_read_unlock();
        mmap_write_unlock(mm);
        flush_tlb_mm(oldmm);
        mmap_write_unlock(oldmm);
+       mas_destroy(&mas);
        dup_userfaultfd_complete(&uf);
 fail_uprobe_end:
        uprobe_end_dup_mmap();

@@ -1092,6 +1105,7 @@ static inline void __mmput(struct mm_struct *mm)
 {
        VM_BUG_ON(atomic_read(&mm->mm_users));

+       mt_clear_in_rcu(&mm->mm_mt);
        uprobe_clear_state(mm);
        exit_aio(mm);
        ksm_exit(mm);

diff --git a/mm/mmap.c b/mm/mmap.c
index 929c2f9eb3f5..1bd43f4db28e 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c

@@ -780,10 +780,6 @@ static inline void vma_mt_store(struct mm_struct *mm, struct vm_area_struct *vma
                GFP_KERNEL);
 }

-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,
--

2.30.2