[PATCH v2 3/5] mm/migrate.c: fix potential indeterminate pte entry in migrate_vma_insert_page()

[Miaohe Lin]

If the zone device page does not belong to un-addressable device memory,
the variable entry will be uninitialized and lead to indeterminate pte
entry ultimately. Fix this unexpected case and warn about it.

Fixes: df6ad69838fc ("mm/device-public-memory: device memory cache coherent 
with CPU")
Signed-off-by: Miaohe Lin <linmia...@huawei.com>
---
 mm/migrate.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/mm/migrate.c b/mm/migrate.c
index 97da1fabdf72..d372be3da9b2 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2972,6 +2972,13 @@ static void migrate_vma_insert_page(struct migrate_vma 
*migrate,
 
                        swp_entry = make_device_private_entry(page, 
vma->vm_flags & VM_WRITE);
                        entry = swp_entry_to_pte(swp_entry);
+               } else {
+                       /*
+                        * For now we only support migrating to un-addressable
+                        * device memory.
+                        */
+                       pr_warn_once("Unsupported ZONE_DEVICE page type.\n");
+                       goto abort;
                }
        } else {
                entry = mk_pte(page, vma->vm_page_prot);
-- 
2.19.1