Re: [PATCH v6 08/13] mm: call pgmap->ops->page_free for DEVICE_GENERIC pages

Am 2021-08-15 um 11:40 a.m. schrieb Christoph Hellwig:

On Fri, Aug 13, 2021 at 01:31:45AM -0500, Alex Sierra wrote:

quoted

Add MEMORY_DEVICE_GENERIC case to free_zone_device_page callback.
Device generic type memory case is now able to free its pages properly.

How is this going to work for the two existing MEMORY_DEVICE_GENERIC
that now change behavior?  And which don't have a ->page_free callback
at all?

That's a good catch. Existing drivers shouldn't need a page_free
callback if they didn't have one before. That means we need to add a
NULL-pointer check in free_device_page.

Regards,
  Felix

quoted

Signed-off-by: Alex Sierra <redacted>
---
 mm/memremap.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/mm/memremap.c b/mm/memremap.c
index 5aa8163fd948..5773e15b6ac9 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c

@@ -459,7 +459,7 @@ struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
 EXPORT_SYMBOL_GPL(get_dev_pagemap);
 
 #ifdef CONFIG_DEV_PAGEMAP_OPS
-static void free_device_private_page(struct page *page)
+static void free_device_page(struct page *page)
 {
 
 	__ClearPageWaiters(page);

@@ -498,7 +498,8 @@ void free_zone_device_page(struct page *page)
 		wake_up_var(&page->_refcount);
 		return;
 	case MEMORY_DEVICE_PRIVATE:
-		free_device_private_page(page);
+	case MEMORY_DEVICE_GENERIC:
+		free_device_page(page);
 		return;
 	default:
 		return;

-- 
2.32.0

---end quoted text---