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From:   Liam Howlett <liam.howlett@oracle.com>
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CC:     "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        Liam Howlett <liam.howlett@oracle.com>
Subject: [PATCH v13 41/70] exec: use VMA iterator instead of linked list
Thread-Topic: [PATCH v13 41/70] exec: use VMA iterator instead of linked list
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Date:   Mon, 22 Aug 2022 15:06:25 +0000
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From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

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 55879fb1ce46..dbc61a4d4c62 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -683,6 +683,8 @@ static int shift_arg_pages(struct vm_area_struct *vma, =
unsigned long shift)
 	unsigned long length =3D old_end - old_start;
 	unsigned long new_start =3D old_start - shift;
 	unsigned long new_end =3D old_end - shift;
+	VMA_ITERATOR(vmi, mm, new_start);
+	struct vm_area_struct *next;
 	struct mmu_gather tlb;
=20
 	BUG_ON(new_start > new_end);
@@ -691,7 +693,7 @@ 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 !=3D find_vma(mm, new_start))
+	if (vma !=3D vma_next(&vmi))
 		return -EFAULT;
=20
 	/*
@@ -710,12 +712,13 @@ static int shift_arg_pages(struct vm_area_struct *vma=
, unsigned long shift)
=20
 	lru_add_drain();
 	tlb_gather_mmu(&tlb, mm);
+	next =3D 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
@@ -724,7 +727,7 @@ 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);
=20
--=20
2.35.1