mm/gup_benchmark: use pin_user_pages for FOLL_LONGTERM flag

According to Documentation/core-api/pin_user_pages.rst, FOLL_PIN is a
prerequisite to FOLL_LONGTERM.  Another way of saying that is,
FOLL_LONGTERM is a specific case, more restrictive case of FOLL_PIN.

Almost all kernel modules are using pin_user_pages() with FOLL_LONGTERM,
mm/gup_benchmark.c seems to the only exception in which FOLL_PIN is not a
prerequisite to FOLL_LONGTERM.

Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Link: http://lkml.kernel.org/r/20200815122056.29508-1-song.bao.hua@hisilicon.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/gup_benchmark.c b/mm/gup_benchmark.c
index be690fa..464cae1 100644 (file)
--- a/mm/gup_benchmark.c
+++ b/mm/gup_benchmark.c
@@ -6,10 +6,10 @@
 #include <linux/debugfs.h>
 
 #define GUP_FAST_BENCHMARK     _IOWR('g', 1, struct gup_benchmark)
-#define GUP_LONGTERM_BENCHMARK _IOWR('g', 2, struct gup_benchmark)
-#define GUP_BENCHMARK          _IOWR('g', 3, struct gup_benchmark)
-#define PIN_FAST_BENCHMARK     _IOWR('g', 4, struct gup_benchmark)
-#define PIN_BENCHMARK          _IOWR('g', 5, struct gup_benchmark)
+#define GUP_BENCHMARK          _IOWR('g', 2, struct gup_benchmark)
+#define PIN_FAST_BENCHMARK     _IOWR('g', 3, struct gup_benchmark)
+#define PIN_BENCHMARK          _IOWR('g', 4, struct gup_benchmark)
+#define PIN_LONGTERM_BENCHMARK _IOWR('g', 5, struct gup_benchmark)
 
 struct gup_benchmark {
        __u64 get_delta_usec;
@@ -28,7 +28,6 @@ static void put_back_pages(unsigned int cmd, struct page **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]);
@@ -36,6 +35,7 @@ static void put_back_pages(unsigned int cmd, struct page **pages,
 
        case PIN_FAST_BENCHMARK:
        case PIN_BENCHMARK:
+       case PIN_LONGTERM_BENCHMARK:
                unpin_user_pages(pages, nr_pages);
                break;
        }
@@ -50,6 +50,7 @@ static void verify_dma_pinned(unsigned int cmd, struct page **pages,
        switch (cmd) {
        case PIN_FAST_BENCHMARK:
        case PIN_BENCHMARK:
+       case PIN_LONGTERM_BENCHMARK:
                for (i = 0; i < nr_pages; i++) {
                        page = pages[i];
                        if (WARN(!page_maybe_dma_pinned(page),
@@ -101,11 +102,6 @@ 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);
@@ -118,6 +114,11 @@ static int __gup_benchmark_ioctl(unsigned int cmd,
                        nr = pin_user_pages(addr, nr, gup->flags, pages + i,
                                            NULL);
                        break;
+               case PIN_LONGTERM_BENCHMARK:
+                       nr = pin_user_pages(addr, nr,
+                                           gup->flags | FOLL_LONGTERM,
+                                           pages + i, NULL);
+                       break;
                default:
                        kvfree(pages);
                        ret = -EINVAL;
@@ -162,10 +163,10 @@ 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_BENCHMARK:
+       case PIN_LONGTERM_BENCHMARK:
                break;
        default:
                return -EINVAL;

diff --git a/tools/testing/selftests/vm/gup_benchmark.c b/tools/testing/selftests/vm/gup_benchmark.c
index 43b4dfe..31f8bb0 100644 (file)
--- a/tools/testing/selftests/vm/gup_benchmark.c
+++ b/tools/testing/selftests/vm/gup_benchmark.c
@@ -15,12 +15,12 @@
 #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)
-#define GUP_BENCHMARK          _IOWR('g', 3, struct gup_benchmark)
+#define GUP_BENCHMARK          _IOWR('g', 2, struct gup_benchmark)
 
 /* Similar to above, but use FOLL_PIN instead of FOLL_GET. */
-#define PIN_FAST_BENCHMARK     _IOWR('g', 4, struct gup_benchmark)
-#define PIN_BENCHMARK          _IOWR('g', 5, struct gup_benchmark)
+#define PIN_FAST_BENCHMARK     _IOWR('g', 3, struct gup_benchmark)
+#define PIN_BENCHMARK          _IOWR('g', 4, struct gup_benchmark)
+#define PIN_LONGTERM_BENCHMARK _IOWR('g', 5, struct gup_benchmark)
 
 /* Just the flags we need, copied from mm.h: */
 #define FOLL_WRITE     0x01    /* check pte is writable */
@@ -52,6 +52,9 @@ int main(int argc, char **argv)
                case 'b':
                        cmd = PIN_BENCHMARK;
                        break;
+               case 'L':
+                       cmd = PIN_LONGTERM_BENCHMARK;
+                       break;
                case 'm':
                        size = atoi(optarg) * MB;
                        break;
@@ -67,9 +70,6 @@ int main(int argc, char **argv)
                case 'T':
                        thp = 0;
                        break;
-               case 'L':
-                       cmd = GUP_LONGTERM_BENCHMARK;
-                       break;
                case 'U':
                        cmd = GUP_BENCHMARK;
                        break;