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From:   Liam Howlett <liam.howlett@oracle.com>
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CC:     Yu Zhao <yuzhao@google.com>
Subject: [PATCH v12 41/69] exec: use VMA iterator instead of linked list
Thread-Topic: [PATCH v12 41/69] exec: use VMA iterator instead of linked list
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Date:   Wed, 20 Jul 2022 02:17:57 +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.

Link: https://lkml.kernel.org/r/20220504011345.662299-26-Liam.Howlett@oracl=
e.com
Link: https://lkml.kernel.org/r/20220621204632.3370049-42-Liam.Howlett@orac=
le.com
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 fs/exec.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index b97afa682ffe..9843cecd031a 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 =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);
@@ -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 !=3D find_vma(mm, new_start))
+	if (vma !=3D vma_next(&vmi))
 		return -EFAULT;
=20
 	/*
@@ -713,12 +715,13 @@ 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
@@ -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);
=20
--=20
2.35.1