mm: refactor the ZONE_DEVICE handling in migrate_vma_insert_page

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

Link: https://lkml.kernel.org/r/20220210072828.2930359-12-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 af0534de618ab25e9d74219b3d674c86bb5e7763..4246dca6c46944193666f8b91a66b2285ad90279 100644 (file)
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2674,26 +2674,25 @@ static void migrate_vma_insert_page(struct migrate_vma *migrate,
         */
        __SetPageUptodate(page);
 
-       if (is_zone_device_page(page)) {
-               if (is_device_private_page(page)) {
-                       swp_entry_t swp_entry;
+       if (is_device_private_page(page)) {
+               swp_entry_t swp_entry;
 
-                       if (vma->vm_flags & VM_WRITE)
-                               swp_entry = make_writable_device_private_entry(
-                                                       page_to_pfn(page));
-                       else
-                               swp_entry = make_readable_device_private_entry(
-                                                       page_to_pfn(page));
-                       entry = swp_entry_to_pte(swp_entry);
-               } else {
-                       /*
-                        * For now we only support migrating to un-addressable
-                        * device memory.
-                        */
+               if (vma->vm_flags & VM_WRITE)
+                       swp_entry = make_writable_device_private_entry(
+                                               page_to_pfn(page));
+               else
+                       swp_entry = make_readable_device_private_entry(
+                                               page_to_pfn(page));
+               entry = swp_entry_to_pte(swp_entry);
+       } else {
+               /*
+                * For now we only support migrating to un-addressable device
+                * memory.
+                */
+               if (is_zone_device_page(page)) {
                        pr_warn_once("Unsupported ZONE_DEVICE page type.\n");
                        goto abort;
                }
-       } else {
                entry = mk_pte(page, vma->vm_page_prot);
                if (vma->vm_flags & VM_WRITE)
                        entry = pte_mkwrite(pte_mkdirty(entry));