Re: [PATCH v6 07/13] mm: add generic type support to migrate_vma helpers

[Christoph Hellwig]

On Fri, Aug 13, 2021 at 01:31:44AM -0500, Alex Sierra wrote:
> Device generic type case added for migrate_vma_pages and
> migrate_vma_check_page helpers.
> Both, generic and private device types have the same
> conditions to decide to migrate pages from/to device
> memory.

This reas a little weird mostly because it doesn't use up the line
length nicely:

Add the device generic type case to the migrate_vma_pages and
migrate_vma_check_page helpers.  This new case is handled identically
to the existing device private case.

> +  * We support migrating to private and generic types 
> for device
> +  * zone memory.

Don't spill comments over 80 characters.

Otherwise looks good:

Reviewed-by: Christoph Hellwig 

[PATCH v6 07/13] mm: add generic type support to migrate_vma helpers

[Alex Sierra]

Device generic type case added for migrate_vma_pages and
migrate_vma_check_page helpers.
Both, generic and private device types have the same
conditions to decide to migrate pages from/to device
memory.

Signed-off-by: Alex Sierra 
---
 mm/migrate.c | 18 +++---
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index e3a10e2a1bb3..f9e6bfa2867c 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2565,7 +2565,7 @@ static bool migrate_vma_check_page(struct page *page)
 * FIXME proper solution is to rework migration_entry_wait() so
 * it does not need to take a reference on page.
 */
-   return is_device_private_page(page);
+   return is_device_page(page);
}
 
/* For file back page */
@@ -2854,7 +2854,7 @@ EXPORT_SYMBOL(migrate_vma_setup);
  * handle_pte_fault()
  *   do_anonymous_page()
  * to map in an anonymous zero page but the struct page will be a ZONE_DEVICE
- * private page.
+ * private or generic page.
  */
 static void migrate_vma_insert_page(struct migrate_vma *migrate,
unsigned long addr,
@@ -2925,10 +2925,14 @@ 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 if (is_device_page(page)) {
+   entry = mk_pte(page, vma->vm_page_prot);
+   if (vma->vm_flags & VM_WRITE)
+   entry = pte_mkwrite(pte_mkdirty(entry));
} else {
/*
-* For now we only support migrating to un-addressable
-* device memory.
+* We support migrating to private and generic types 
for device
+* zone memory.
 */
pr_warn_once("Unsupported ZONE_DEVICE page type.\n");
goto abort;
@@ -3034,10 +3038,10 @@ void migrate_vma_pages(struct migrate_vma *migrate)
mapping = page_mapping(page);
 
if (is_zone_device_page(newpage)) {
-   if (is_device_private_page(newpage)) {
+   if (is_device_page(newpage)) {
/*
-* For now only support private anonymous when
-* migrating to un-addressable device memory.
+* For now only support private and generic
+* anonymous when migrating to device memory.
 */
if (mapping) {
migrate->src[i] &= ~MIGRATE_PFN_MIGRATE;
-- 
2.32.0