[PATCH 18/19] mm/gup: remove support for gup(FOLL_LONGTERM)

[John Hubbard <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 e51b3820a995..9a28935a2cb1 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1744,11 +1744,11 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
 		struct vm_area_struct **vmas)
 {
 	/*
-	 * As detailed above, 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:
+	 * As detailed above, 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 2bb0f5df4803..de6941855b7e 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]);
@@ -94,11 +93,6 @@ static int __gup_benchmark_ioctl(unsigned int cmd,
 			nr = get_user_pages_fast(addr, nr, gup->flags & 1,
 						 pages + i);
 			break;
-		case GUP_LONGTERM_BENCHMARK:
-			nr = get_user_pages(addr, nr,
-					    (gup->flags & 1) | FOLL_LONGTERM,
-					    pages + i, NULL);
-			break;
 		case GUP_BENCHMARK:
 			nr = get_user_pages(addr, nr, gup->flags & 1, pages + i,
 					    NULL);
@@ -157,7 +151,6 @@ 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 c5c934c0f402..5ef3cf8f3da5 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)
 
 /*
@@ -46,7 +46,7 @@ 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;
@@ -72,9 +72,6 @@ int main(int argc, char **argv)
 		case 'T':
 			thp = 0;
 			break;
-		case 'L':
-			cmd = GUP_LONGTERM_BENCHMARK;
-			break;
 		case 'U':
 			cmd = GUP_BENCHMARK;
 			break;
-- 
2.23.0