[RFC PATCH 04/10] mm: update print_bad_page_map() to show virtual page index

[Lorenzo Stoakes]

This is potentially useful debugging information and matches the existing
page offset provided.

We only do so if the VMA is not a shared mapping, as shared mappings ignore
the virtual page offset.

We use __linear_virt_page_offset() as the VMA may be shared.

Signed-off-by: Lorenzo Stoakes <ljs@xxxxxxxxxx>
---
 mm/memory.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index f5eb06544ba4..7890e5200ecb 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -588,21 +588,23 @@ static void print_bad_page_map(struct vm_area_struct *vma,
 		enum pgtable_level level)
 {
 	struct address_space *mapping;
-	pgoff_t index;
+	pgoff_t index, virt_index;
 
 	if (is_bad_page_map_ratelimited())
 		return;
 
 	mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
 	index = linear_page_index(vma, addr);
+	virt_index = __linear_virt_page_index(vma, addr);
 
 	pr_alert("BUG: Bad page map in process %s  %s:%08llx", current->comm,
 		 pgtable_level_to_str(level), entry);
 	__print_bad_page_map_pgtable(vma->vm_mm, addr);
 	if (page)
 		dump_page(page, "bad page map");
-	pr_alert("addr:%px vm_flags:%08lx anon_vma:%px mapping:%px index:%lx\n",
-		 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
+	pr_alert("addr:%px vm_flags:%08lx anon_vma:%px mapping:%px index:%lx virt_index:%lx\n",
+		 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index,
+		 virt_index);
 	pr_alert("file:%pD fault:%ps mmap:%ps mmap_prepare: %ps read_folio:%ps\n",
 		 vma->vm_file,
 		 vma->vm_ops ? vma->vm_ops->fault : NULL,
-- 
2.54.0