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

John Hubbard
2019-10-30T22:50:48Z

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