From: Liam R. Howlett <Liam.Howlett@oracle.com>
Date: Mon, 24 Apr 2023 20:36:31 +0000 (-0400)
Subject: mm: Remove VMA Iterator reset from vma_expand()
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=933e673c4e566807fdfcbdc0cdbf92a88b1e9028;p=users%2Fjedix%2Flinux-maple.git

mm: Remove VMA Iterator reset from vma_expand()

Update callers to vma_expand() to set the vma iterator to the correct
position.  Detect the incorrect location with a MAS_WARN_ON() to debug
what is going on.

Update the caller in shift_arg_pages() to set the vma iterator
correctly.

Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---

diff --git a/fs/exec.c b/fs/exec.c
index 87cf3a2f0e9a1..8a9a529ba1805 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -696,6 +696,8 @@ static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 	if (vma != vma_next(&vmi))
 		return -EFAULT;
 
+	vma_iter_prev_range(&vmi);
+
 	/*
 	 * cover the whole range: [new_start, old_end)
 	 */
diff --git a/mm/mmap.c b/mm/mmap.c
index 4c7c0e2c8fab7..3e265c7deaeb0 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -680,8 +680,7 @@ int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma,
 
 	vma_prepare(&vp);
 	vma_adjust_trans_huge(vma, start, end, 0);
-	/* VMA iterator points to previous, so set to start if necessary */
-	if (vma_iter_addr(vmi) != start)
+	if (MAS_WARN_ON(&vmi->mas, vma_iter_addr(vmi) != start))
 		vma_iter_set(vmi, start);
 
 	vma->vm_start = start;