From dbde17041cbf26606436f844457b12f9a45b90d7 Mon Sep 17 00:00:00 2001
From: Lorenzo Stoakes <ljs@kernel.org>
Date: Fri, 10 Jul 2026 21:16:46 +0100
Subject: [PATCH] mm/rmap: update mm/interval_tree.c comments

Update the file comment to clarify that both file-backed and anonymous
interval trees are provided, referencing the relevant data types for
clarity.

Also add comments to indicate which parts of the file apply to each.

While we're here, convert the VM_BUG_ON_VMA() to VM_WARN_ON_ONCE_VMA().

Link: https://lore.kernel.org/20260710-b4-pre-scalable-cow-v2-5-2a5aa403d977@kernel.org
Signed-off-by: Lorenzo Stoakes <ljs@kernel.org>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Reviewed-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Ackerley Tng <ackerleytng@google.com>
Cc: David Hildenbrand (Arm) <david@kernel.org>
Cc: Kai Huang <kai.huang@intel.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: SJ Park <sj@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Liam R. Howlett (Oracle) <liam@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 mm/interval_tree.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/mm/interval_tree.c b/mm/interval_tree.c
index 344d1f5946c7..2d50bc6228c4 100644
--- a/mm/interval_tree.c
+++ b/mm/interval_tree.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * mm/interval_tree.c - interval tree for mapping->i_mmap
+ * mm/interval_tree.c - interval tree for address_space->i_mmap and
+ * anon_vma->rb_root
  *
  * Copyright (C) 2012, Michel Lespinasse <walken@google.com>
  */
@@ -10,6 +11,8 @@
 #include <linux/rmap.h>
 #include <linux/interval_tree_generic.h>
 
+/* File-backed interval tree (address_space->i_mmap) */
+
 INTERVAL_TREE_DEFINE(struct vm_area_struct, shared.rb,
 		     unsigned long, shared.rb_subtree_last,
 		     vma_start_pgoff, vma_last_pgoff, /* empty */, vma_interval_tree)
@@ -23,7 +26,7 @@ void vma_interval_tree_insert_after(struct vm_area_struct *node,
 	struct vm_area_struct *parent;
 	unsigned long last = vma_last_pgoff(node);
 
-	VM_BUG_ON_VMA(vma_start_pgoff(node) != vma_start_pgoff(prev), node);
+	VM_WARN_ON_ONCE_VMA(vma_start_pgoff(node) != vma_start_pgoff(prev), node);
 
 	if (!prev->shared.rb.rb_right) {
 		parent = prev;
@@ -48,6 +51,8 @@ void vma_interval_tree_insert_after(struct vm_area_struct *node,
 			    &vma_interval_tree_augment);
 }
 
+/* Anonymous interval tree (anon_vma->rb_root) */
+
 static inline unsigned long avc_start_pgoff(struct anon_vma_chain *avc)
 {
 	return vma_start_pgoff(avc->vma);