diff mbox series

[RFC,5/5] mm: changes to unref pages with Generic type

Message ID 20210527230809.3701-6-Felix.Kuehling@amd.com (mailing list archive)
State New, archived
Headers show
Series Support DEVICE_GENERIC memory in migrate_vma_* | expand

Commit Message

Felix Kuehling May 27, 2021, 11:08 p.m. UTC 
From: Alex Sierra <alex.sierra@amd.com>

pages in device mapping refcounts are 1-based, instead
of 0-based. If refcount 1, means it can be freed.
This logic is not set for Generic memory type. Therefore,
its release is threated as a normal page, instead of
the callback device driver release it.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
---
 include/linux/mm.h | 1 +
 mm/memremap.c      | 5 ++++-
 2 files changed, 5 insertions(+), 1 deletion(-)

Comments

Christoph Hellwig May 29, 2021, 6:42 a.m. UTC | #1 
On Thu, May 27, 2021 at 07:08:09PM -0400, Felix Kuehling wrote:
> From: Alex Sierra <alex.sierra@amd.com>
> 
> pages in device mapping refcounts are 1-based, instead
> of 0-based. If refcount 1, means it can be freed.
> This logic is not set for Generic memory type. Therefore,
> its release is threated as a normal page, instead of
> the callback device driver release it.

So we really need to stop this magic one off refcount.  We had a WIP
patchset to do that, and we need to finish that off instad of piling on
more hacks.
Felix Kuehling May 29, 2021, 6:44 p.m. UTC | #2 
Am 2021-05-29 um 2:42 a.m. schrieb Christoph Hellwig:
> On Thu, May 27, 2021 at 07:08:09PM -0400, Felix Kuehling wrote:
>> From: Alex Sierra <alex.sierra@amd.com>
>>
>> pages in device mapping refcounts are 1-based, instead
>> of 0-based. If refcount 1, means it can be freed.
>> This logic is not set for Generic memory type. Therefore,
>> its release is threated as a normal page, instead of
>> the callback device driver release it.
> So we really need to stop this magic one off refcount.  We had a WIP
> patchset to do that, and we need to finish that off instad of piling on
> more hacks.

Sure. I'll be happy to help with that, if I can.

Thanks,
  Felix
diff mbox series

Patch

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 1af7b9b76948..83bd2f3e111b 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1130,6 +1130,7 @@  static inline bool page_is_devmap_managed(struct page *page)
 	switch (page->pgmap->type) {
 	case MEMORY_DEVICE_PRIVATE:
 	case MEMORY_DEVICE_FS_DAX:
+	case MEMORY_DEVICE_GENERIC:
 		return true;
 	default:
 		break;
diff --git a/mm/memremap.c b/mm/memremap.c
index 16b2fb482da1..d2563fbcf987 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -44,6 +44,7 @@  EXPORT_SYMBOL(devmap_managed_key);
 static void devmap_managed_enable_put(struct dev_pagemap *pgmap)
 {
 	if (pgmap->type == MEMORY_DEVICE_PRIVATE ||
+	    pgmap->type == MEMORY_DEVICE_GENERIC ||
 	    pgmap->type == MEMORY_DEVICE_FS_DAX)
 		static_branch_dec(&devmap_managed_key);
 }
@@ -51,6 +52,7 @@  static void devmap_managed_enable_put(struct dev_pagemap *pgmap)
 static void devmap_managed_enable_get(struct dev_pagemap *pgmap)
 {
 	if (pgmap->type == MEMORY_DEVICE_PRIVATE ||
+	    pgmap->type == MEMORY_DEVICE_GENERIC ||
 	    pgmap->type == MEMORY_DEVICE_FS_DAX)
 		static_branch_inc(&devmap_managed_key);
 }
@@ -480,7 +482,8 @@  EXPORT_SYMBOL_GPL(get_dev_pagemap);
 void free_devmap_managed_page(struct page *page)
 {
 	/* notify page idle for dax */
-	if (!is_device_private_page(page)) {
+	if (!(is_device_private_page(page) ||
+	    is_device_generic_page(page))) {
 		wake_up_var(&page->_refcount);
 		return;
 	}