[HMM v13 05/18] mm/ZONE_DEVICE/devmem_pages_remove: allow early removal of device memory

[JÃrÃme Glisse]

HMM wants to remove device memory early before device tear down so add an
helper to do that.

Signed-off-by: JÃrÃme Glisse <jglisse@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
---
 include/linux/memremap.h |  7 +++++++
 kernel/memremap.c        | 14 ++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index 469c88d..b6f03e9 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -60,6 +60,7 @@ void *devm_memremap_pages(struct device *dev, struct resource *res,
 			  struct percpu_ref *ref, struct vmem_altmap *altmap,
 			  struct dev_pagemap **ppgmap, int flags);
 struct dev_pagemap *find_dev_pagemap(resource_size_t phys);
+int devm_memremap_pages_remove(struct device *dev, struct dev_pagemap *pgmap);
 
 static inline bool is_addressable_page(const struct page *page)
 {
@@ -88,6 +89,12 @@ static inline struct dev_pagemap *find_dev_pagemap(resource_size_t phys)
 	return NULL;
 }
 
+static inline int devm_memremap_pages_remove(struct device *dev,
+					     struct dev_pagemap *pgmap)
+{
+	return -EINVAL;
+}
+
 static inline bool is_addressable_page(const struct page *page)
 {
 	return true;
diff --git a/kernel/memremap.c b/kernel/memremap.c
index 3d28048..cf83928 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -401,6 +401,20 @@ void *devm_memremap_pages(struct device *dev, struct resource *res,
 }
 EXPORT_SYMBOL(devm_memremap_pages);
 
+static int devm_page_map_match(struct device *dev, void *data, void *match_data)
+{
+	struct page_map *page_map = data;
+
+	return &page_map->pgmap == match_data;
+}
+
+int devm_memremap_pages_remove(struct device *dev, struct dev_pagemap *pgmap)
+{
+	return devres_release(dev, &devm_memremap_pages_release,
+			      &devm_page_map_match, pgmap);
+}
+EXPORT_SYMBOL(devm_memremap_pages_remove);
+
 unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
 {
 	/* number of pfns from base where pfn_to_page() is valid */
-- 
2.4.3