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Subject[PATCH 1/2] mm: introduce put_user_page(), placeholder version
Date
From: John Hubbard <jhubbard@nvidia.com>

Introduces put_user_page(), which simply calls put_page().
This provides a safe way to update all get_user_pages*() callers,
so that they call put_user_page(), instead of put_page().

Also adds release_user_pages(), a drop-in replacement for
release_pages(). This is intended to be easily grep-able,
for later performance improvements, since release_user_pages
is not batched like release_pages is, and is significantly
slower.

Subsequent patches will add functionality to put_user_page().

Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
include/linux/mm.h | 14 ++++++++++++++
1 file changed, 14 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index a0fbb9ffe380..db4a211aad79 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -923,6 +923,20 @@ static inline void put_page(struct page *page)
__put_page(page);
}

+/* Placeholder version, until all get_user_pages*() callers are updated. */
+static inline void put_user_page(struct page *page)
+{
+ put_page(page);
+}
+
+/* A drop-in replacement for release_pages(): */
+static inline void release_user_pages(struct page **pages,
+ unsigned long npages)
+{
+ while (npages)
+ put_user_page(pages[--npages]);
+}
+
#if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)
#define SECTION_IN_PAGE_FLAGS
#endif
--
2.18.0
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