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SubjectRe: [PATCH v4 23/23] mm/gup: remove support for gup(FOLL_LONGTERM)
On Tue, Nov 12, 2019 at 08:27:10PM -0800, John Hubbard wrote:
> 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)))

Don't we want to block FOLL_LONGTERM in get_user_pages_fast() as well after all
this?

Ira

> 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
>

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