[PATCH v4 23/23] mm/gup: remove support for gup(FOLL_LONGTERM)

From: John Hubbard <jhubbard@nvidia.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Al Viro" <viro@zeniv.linux.org.uk>,
	"Alex Williamson" <alex.williamson@redhat.com>,
	"Benjamin Herrenschmidt" <benh@kernel.crashing.org>,
	"Björn Töpel" <bjorn.topel@intel.com>,
	"Christoph Hellwig" <hch@infradead.org>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Daniel Vetter" <daniel@ffwll.ch>,
	"Dave Chinner" <david@fromorbit.com>,
	"David Airlie" <airlied@linux.ie>,
	"David S . Miller" <davem@davemloft.net>,
	"Ira Weiny" <ira.weiny@intel.com>, "Jan Kara" <jack@suse.cz>,
	"Jason Gunthorpe" <jgg@ziepe.ca>, "Jens Axboe" <axboe@kernel.dk>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Magnus Karlsson" <magnus.karlsson@intel.com>,
	"Mauro Carvalho Chehab" <mchehab@kernel.org>,
	"Michael Ellerman" <mpe@ellerman.id.au>,
	"Michal Hocko" <mhocko@suse.com>,
	"Mike Kravetz" <mike.kravetz@oracle.com>,
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	"Shuah Khan" <shuah@kernel.org>,
	"Vlastimil Babka" <vbabka@suse.cz>,
	bpf@vger.kernel.org, dri-devel@lists.freedesktop.org,
	kvm@vger.kernel.org, linux-block@vger.kernel.org,
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	LKML <linux-kernel@vger.kernel.org>,
	"John Hubbard" <jhubbard@nvidia.com>
Subject: [PATCH v4 23/23] mm/gup: remove support for gup(FOLL_LONGTERM)
Date: Tue, 12 Nov 2019 20:27:10 -0800	[thread overview]
Message-ID: <20191113042710.3997854-24-jhubbard@nvidia.com> (raw)
In-Reply-To: <20191113042710.3997854-1-jhubbard@nvidia.com>

Now that all other kernel callers of get_user_pages(FOLL_LONGTERM)
have been converted to pin_longterm_pages(), lock it down:

1) Add an assertion to get_user_pages(), preventing callers from
   passing FOLL_LONGTERM (in addition to the existing assertion that
   prevents FOLL_PIN).

2) Remove the associated GUP_LONGTERM_BENCHMARK test.

Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
 mm/gup.c                                   | 8 ++++----
 mm/gup_benchmark.c                         | 9 +--------
 tools/testing/selftests/vm/gup_benchmark.c | 7 ++-----
 3 files changed, 7 insertions(+), 17 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 82e7e4ce5027..90f5f95ee7ac 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1756,11 +1756,11 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
 		struct vm_area_struct **vmas)
 {
 	/*
-	 * FOLL_PIN must only be set internally by the pin_user_page*() and
-	 * pin_longterm_*() APIs, never directly by the caller, so enforce that
-	 * with an assertion:
+	 * FOLL_PIN and FOLL_LONGTERM must only be set internally by the
+	 * pin_user_page*() and pin_longterm_*() APIs, never directly by the
+	 * caller, so enforce that with an assertion:
 	 */
-	if (WARN_ON_ONCE(gup_flags & FOLL_PIN))
+	if (WARN_ON_ONCE(gup_flags & (FOLL_PIN | FOLL_LONGTERM)))
 		return -EINVAL;
 
 	return __gup_longterm_locked(current, current->mm, start, nr_pages,
diff --git a/mm/gup_benchmark.c b/mm/gup_benchmark.c
index 8f980d91dbf5..679f0e6a0adb 100644
--- a/mm/gup_benchmark.c
+++ b/mm/gup_benchmark.c
@@ -6,7 +6,7 @@
 #include <linux/debugfs.h>
 
 #define GUP_FAST_BENCHMARK	_IOWR('g', 1, struct gup_benchmark)
-#define GUP_LONGTERM_BENCHMARK	_IOWR('g', 2, struct gup_benchmark)
+/* Command 2 has been deleted. */
 #define GUP_BENCHMARK		_IOWR('g', 3, struct gup_benchmark)
 #define PIN_FAST_BENCHMARK	_IOWR('g', 4, struct gup_benchmark)
 #define PIN_LONGTERM_BENCHMARK	_IOWR('g', 5, struct gup_benchmark)
@@ -28,7 +28,6 @@ static void put_back_pages(int cmd, struct page **pages, unsigned long nr_pages)
 
 	switch (cmd) {
 	case GUP_FAST_BENCHMARK:
-	case GUP_LONGTERM_BENCHMARK:
 	case GUP_BENCHMARK:
 		for (i = 0; i < nr_pages; i++)
 			put_page(pages[i]);
@@ -97,11 +96,6 @@ static int __gup_benchmark_ioctl(unsigned int cmd,
 			nr = get_user_pages_fast(addr, nr, gup->flags,
 						 pages + i);
 			break;
-		case GUP_LONGTERM_BENCHMARK:
-			nr = get_user_pages(addr, nr,
-					    gup->flags | FOLL_LONGTERM,
-					    pages + i, NULL);
-			break;
 		case GUP_BENCHMARK:
 			nr = get_user_pages(addr, nr, gup->flags, pages + i,
 					    NULL);
@@ -159,7 +153,6 @@ static long gup_benchmark_ioctl(struct file *filep, unsigned int cmd,
 
 	switch (cmd) {
 	case GUP_FAST_BENCHMARK:
-	case GUP_LONGTERM_BENCHMARK:
 	case GUP_BENCHMARK:
 	case PIN_FAST_BENCHMARK:
 	case PIN_LONGTERM_BENCHMARK:
diff --git a/tools/testing/selftests/vm/gup_benchmark.c b/tools/testing/selftests/vm/gup_benchmark.c
index 03928e47a86f..836b7082db13 100644
--- a/tools/testing/selftests/vm/gup_benchmark.c
+++ b/tools/testing/selftests/vm/gup_benchmark.c
@@ -15,7 +15,7 @@
 #define PAGE_SIZE sysconf(_SC_PAGESIZE)
 
 #define GUP_FAST_BENCHMARK	_IOWR('g', 1, struct gup_benchmark)
-#define GUP_LONGTERM_BENCHMARK	_IOWR('g', 2, struct gup_benchmark)
+/* Command 2 has been deleted. */
 #define GUP_BENCHMARK		_IOWR('g', 3, struct gup_benchmark)
 
 /*
@@ -49,7 +49,7 @@ int main(int argc, char **argv)
 	char *file = "/dev/zero";
 	char *p;
 
-	while ((opt = getopt(argc, argv, "m:r:n:f:abctTLUuwSH")) != -1) {
+	while ((opt = getopt(argc, argv, "m:r:n:f:abctTUuwSH")) != -1) {
 		switch (opt) {
 		case 'a':
 			cmd = PIN_FAST_BENCHMARK;
@@ -75,9 +75,6 @@ int main(int argc, char **argv)
 		case 'T':
 			thp = 0;
 			break;
-		case 'L':
-			cmd = GUP_LONGTERM_BENCHMARK;
-			break;
 		case 'U':
 			cmd = GUP_BENCHMARK;
 			break;
-- 
2.24.0

