mm: refactor the ZONE_DEVICE handling in migrate_vma_pages

Make the flow a little more clear and prepare for adding a new
ZONE_DEVICE memory type.

Link: https://lkml.kernel.org/r/20220210072828.2930359-13-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Tested-by: "Sierra Guiza, Alejandro (Alex)" <alex.sierra@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Chaitanya Kulkarni <kch@nvidia.com>
Cc: Christian Knig <christian.koenig@amd.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Karol Herbst <kherbst@redhat.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: "Pan, Xinhui" <Xinhui.Pan@amd.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

diff --git a/mm/migrate.c b/mm/migrate.c
index 4246dca..7dffd5f 100644 (file)
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2792,24 +2792,21 @@ void migrate_vma_pages(struct migrate_vma *migrate)
 
                mapping = page_mapping(page);
 
-               if (is_zone_device_page(newpage)) {
-                       if (is_device_private_page(newpage)) {
-                               /*
-                                * For now only support private anonymous when
-                                * migrating to un-addressable device memory.
-                                */
-                               if (mapping) {
-                                       migrate->src[i] &= ~MIGRATE_PFN_MIGRATE;
-                                       continue;
-                               }
-                       } else {
-                               /*
-                                * Other types of ZONE_DEVICE page are not
-                                * supported.
-                                */
+               if (is_device_private_page(newpage)) {
+                       /*
+                        * For now only support private anonymous when migrating
+                        * to un-addressable device memory.
+                        */
+                       if (mapping) {
                                migrate->src[i] &= ~MIGRATE_PFN_MIGRATE;
                                continue;
                        }
+               } else if (is_zone_device_page(newpage)) {
+                       /*
+                        * Other types of ZONE_DEVICE page are not supported.
+                        */
+                       migrate->src[i] &= ~MIGRATE_PFN_MIGRATE;
+                       continue;
                }
 
                r = migrate_page(mapping, newpage, page, MIGRATE_SYNC_NO_COPY);