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From: john.hubbard@gmail.com
To: Matthew Wilcox <willy@infradead.org>,
	Michal Hocko <mhocko@kernel.org>,
	Christopher Lameter <cl@linux.com>,
	Jason Gunthorpe <jgg@ziepe.ca>,
	Dan Williams <dan.j.williams@intel.com>, Jan Kara <jack@suse.cz>,
	Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
	linux-rdma <linux-rdma@vger.kernel.org>,
	linux-fsdevel@vger.kernel.org, John Hubbard <jhubbard@nvidia.com>
Subject: [PATCH 1/2] mm: introduce put_user_page(), placeholder version
Date: Mon,  9 Jul 2018 01:05:53 -0700
Message-ID: <20180709080554.21931-2-jhubbard@nvidia.com> (raw)
In-Reply-To: <20180709080554.21931-1-jhubbard@nvidia.com>

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


  reply index

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-09  8:05 [PATCH 0/2] mm/fs: put_user_page() proposal john.hubbard
2018-07-09  8:05 ` john.hubbard [this message]
2018-07-09 10:08   ` [PATCH 1/2] mm: introduce put_user_page(), placeholder version kbuild test robot
2018-07-09 18:48     ` John Hubbard
2018-07-09 15:53   ` Jason Gunthorpe
2018-07-09 16:11     ` Jan Kara
2018-07-09  8:05 ` [PATCH 2/2] goldfish_pipe/mm: convert to the new put_user_page() call john.hubbard
2018-07-09  8:49 ` [PATCH 0/2] mm/fs: put_user_page() proposal Nicholas Piggin
2018-07-09 16:08   ` Jan Kara
2018-07-09 17:16     ` Matthew Wilcox
2018-07-09 19:47       ` Jan Kara
2018-07-09 19:56         ` Jason Gunthorpe
2018-07-10  7:51           ` Jan Kara
2018-07-09 20:00         ` Matthew Wilcox
2018-07-10  8:21           ` Jan Kara
2018-07-09 16:27 ` Jan Kara

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