linux-kernel - [PATCH v4 39/49] mm/mmap: move anon_vma setting in __vma

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Date:   Fri, 20 Jan 2023 11:26:40 -0500
From:   "Liam R. Howlett" <Liam.Howlett@...cle.com>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        maple-tree@...ts.infradead.org
Cc:     "Liam R. Howlett" <Liam.Howlett@...cle.com>,
        "Liam R . Howlett" <Liam.Howlett@...cle.com>
Subject: [PATCH v4 39/49] mm/mmap: move anon_vma setting in __vma_adjust()

From: "Liam R. Howlett" <Liam.Howlett@...cle.com>

Move the anon_vma setting & warn_no up the function.  This is done to
clear up the locking later.

Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
---
 mm/mmap.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 56483b837ef9..b83c70c59a76 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -685,6 +685,14 @@ int __vma_adjust(struct vma_iterator *vmi, struct vm_area_struct *vma,
 	if (vma_iter_prealloc(vmi))
 		return -ENOMEM;
 
+	anon_vma = vma->anon_vma;
+	if (!anon_vma && adjust_next)
+		anon_vma = next->anon_vma;
+
+	if (anon_vma)
+		VM_WARN_ON(adjust_next && next->anon_vma &&
+			   anon_vma != next->anon_vma);
+
 	vma_adjust_trans_huge(orig_vma, start, end, adjust_next);
 	if (file) {
 		mapping = file->f_mapping;
@@ -706,12 +714,7 @@ int __vma_adjust(struct vma_iterator *vmi, struct vm_area_struct *vma,
 		}
 	}
 
-	anon_vma = vma->anon_vma;
-	if (!anon_vma && adjust_next)
-		anon_vma = next->anon_vma;
 	if (anon_vma) {
-		VM_WARN_ON(adjust_next && next->anon_vma &&
-			   anon_vma != next->anon_vma);
 		anon_vma_lock_write(anon_vma);
 		anon_vma_interval_tree_pre_update_vma(vma);
 		if (adjust_next)
-- 
2.35.1