[PATCH v7 42/70] exec: Use VMA iterator instead of linked list

Liam Howlett
2022-04-04T14:39:18Z

Remove a use of the vm_next list by doing the initial lookup with the
VMA iterator and then using it to find the next entry.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
---
fs/exec.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index 14e7278a1ab8..b5e3bfd52b53 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -686,6 +686,8 @@ static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
unsigned long length = old_end - old_start;
unsigned long new_start = old_start - shift;
unsigned long new_end = old_end - shift;
+ VMA_ITERATOR(vmi, mm, new_start);
+ struct vm_area_struct *next;
struct mmu_gather tlb;

BUG_ON(new_start > new_end);
@@ -694,7 +696,7 @@ static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
* ensure there are no vmas between where we want to go
* and where we are
*/
- if (vma != find_vma(mm, new_start))
+ if (vma != vma_next(&vmi))
return -EFAULT;

/*
@@ -713,12 +715,13 @@ static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)

lru_add_drain();
tlb_gather_mmu(&tlb, mm);
+ next = vma_next(&vmi);
if (new_end > old_start) {
/*
* when the old and new regions overlap clear from new_end.
*/
free_pgd_range(&tlb, new_end, old_end, new_end,
- vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
+ next ? next->vm_start : USER_PGTABLES_CEILING);
} else {
/*
* otherwise, clean from old_start; this is done to not touch
@@ -727,7 +730,7 @@ static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
* for the others its just a little faster.
*/
free_pgd_range(&tlb, old_start, old_end, new_end,
- vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
+ next ? next->vm_start : USER_PGTABLES_CEILING);
}
tlb_finish_mmu(&tlb);

--
2.34.1