From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>
Instead of moving (or leaving) the vma iterator pointing at the previous
vma, leave it pointing at the insert location. Pointing the vma
iterator at the insert location allows for a cleaner walk of the vma
tree for MAP_FIXED and the no expansion cases.
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
---
mm/mmap.c | 28 ++++++++++++++--------------
1 file changed, 14 insertions(+), 14 deletions(-)
diff --git a/mm/mmap.c b/mm/mmap.c
index f5b33de4e717..ecf55d32e804 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2963,11 +2963,12 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
vms_complete_munmap_vmas(&vms, &mas_detach);
next = vms.next;
prev = vms.prev;
- vma_prev(&vmi);
vma = NULL;
} else {
next = vma_next(&vmi);
prev = vma_prev(&vmi);
+ if (prev)
+ vma_iter_next_range(&vmi);
}
/*
@@ -2980,11 +2981,8 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
vm_flags |= VM_ACCOUNT;
}
- if (vm_flags & VM_SPECIAL) {
- if (prev)
- vma_iter_next_range(&vmi);
+ if (vm_flags & VM_SPECIAL)
goto cannot_expand;
- }
/* Attempt to expand an old mapping */
/* Check next */
@@ -3005,19 +3003,21 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
merge_start = prev->vm_start;
vma = prev;
vm_pgoff = prev->vm_pgoff;
- } else if (prev) {
- vma_iter_next_range(&vmi);
+ vma_prev(&vmi);
}
- /* Actually expand, if possible */
- if (vma &&
- !vma_expand(&vmi, vma, merge_start, merge_end, vm_pgoff, next)) {
- khugepaged_enter_vma(vma, vm_flags);
- goto expanded;
+ if (vma) {
+ /* Actually expand, if possible */
+ if (!vma_expand(&vmi, vma, merge_start, merge_end, vm_pgoff, next)) {
+ khugepaged_enter_vma(vma, vm_flags);
+ goto expanded;
+ }
+
+ /* If the expand fails, then reposition the vma iterator */
+ if (unlikely(vma == prev))
+ vma_iter_set(&vmi, addr);
}
- if (vma == prev)
- vma_iter_set(&vmi, addr);
cannot_expand:
/*
--
2.43.0
