From: Christoph Hellwig <hch@lst.de>
Date: Wed, 16 Feb 2022 15:31:37 +1100
Subject: mm: refactor the ZONE_DEVICE handling in migrate_vma_insert_page
Git-commit: 1776c0d102482d4aeccd56e404285bc47a481be8
Patch-mainline: v5.18-rc1
References: jsc#PED-1294

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>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
 mm/migrate.c |   31 +++++++++++++++----------------
 1 file changed, 15 insertions(+), 16 deletions(-)

--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2768,26 +2768,25 @@ static void migrate_vma_insert_page(stru
 	 */
 	__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));