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selftests/vm: gup_test: fix test flag
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In gup_test both gup_flags and test_flags use the same flags field.
This is broken.

Farther, in the actual gup_test.c all the passed gup_flags are erased
and unconditionally replaced with FOLL_WRITE.

Which means that test_flags are ignored, and code like this always
performs pin dump test:

155  			if (gup->flags & GUP_TEST_FLAG_DUMP_PAGES_USE_PIN)
156  				nr = pin_user_pages(addr, nr, gup->flags,
157  						    pages + i, NULL);
158  			else
159  				nr = get_user_pages(addr, nr, gup->flags,
160  						    pages + i, NULL);
161  			break;

Add a new test_flags field, to allow raw gup_flags to work.  Add a new
subcommand for DUMP_USER_PAGES_TEST to specify that pin test should be
performed.

Remove unconditional overwriting of gup_flags via FOLL_WRITE.  But,
preserve the previous behaviour where FOLL_WRITE was the default flag,
and add a new option "-W" to unset FOLL_WRITE.

Rename flags with gup_flags.

With the fix, dump works like this:

  root@virtme:/# gup_test  -c
  ---- page #0, starting from user virt addr: 0x7f8acb9e4000
  page:00000000d3d2ee27 refcount:2 mapcount:1 mapping:0000000000000000
  index:0x0 pfn:0x100bcf
  anon flags: 0x300000000080016(referenced|uptodate|lru|swapbacked)
  raw: 0300000000080016 ffffd0e204021608 ffffd0e208df2e88 ffff8ea04243ec61
  raw: 0000000000000000 0000000000000000 0000000200000000 0000000000000000
  page dumped because: gup_test: dump_pages() test
  DUMP_USER_PAGES_TEST: done

  root@virtme:/# gup_test  -c -p
  ---- page #0, starting from user virt addr: 0x7fd19701b000
  page:00000000baed3c7d refcount:1025 mapcount:1 mapping:0000000000000000
  index:0x0 pfn:0x108008
  anon flags: 0x300000000080014(uptodate|lru|swapbacked)
  raw: 0300000000080014 ffffd0e204200188 ffffd0e205e09088 ffff8ea04243ee71
  raw: 0000000000000000 0000000000000000 0000040100000000 0000000000000000
  page dumped because: gup_test: dump_pages() test
  DUMP_USER_PAGES_TEST: done

Refcount shows the difference between pin vs no-pin case.
Also change type of nr from int to long, as it counts number of pages.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Pavel Tatashin <[email protected]>
Reviewed-by: John Hubbard <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Ira Weiny <[email protected]>
Cc: James Morris <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Sasha Levin <[email protected]>
Cc: Steven Rostedt (VMware) <[email protected]>
Cc: Tyler Hicks <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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@soleen @torvalds
soleen authored and torvalds committed May 5, 2021
1 parent f68749e commit 79dbf13
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Showing 3 changed files with 23 additions and 18 deletions.
23 changes: 10 additions & 13 deletions mm/gup_test.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -94,7 +94,7 @@ static int __gup_test_ioctl(unsigned int cmd,
{
ktime_t start_time, end_time;
unsigned long i, nr_pages, addr, next;
int nr;
long nr;
struct page **pages;
int ret = 0;
bool needs_mmap_lock =
Expand Down Expand Up @@ -126,37 +126,34 @@ static int __gup_test_ioctl(unsigned int cmd,
nr = (next - addr) / PAGE_SIZE;
}

/* Filter out most gup flags: only allow a tiny subset here: */
gup->flags &= FOLL_WRITE;

switch (cmd) {
case GUP_FAST_BENCHMARK:
nr = get_user_pages_fast(addr, nr, gup->flags,
nr = get_user_pages_fast(addr, nr, gup->gup_flags,
pages + i);
break;
case GUP_BASIC_TEST:
nr = get_user_pages(addr, nr, gup->flags, pages + i,
nr = get_user_pages(addr, nr, gup->gup_flags, pages + i,
NULL);
break;
case PIN_FAST_BENCHMARK:
nr = pin_user_pages_fast(addr, nr, gup->flags,
nr = pin_user_pages_fast(addr, nr, gup->gup_flags,
pages + i);
break;
case PIN_BASIC_TEST:
nr = pin_user_pages(addr, nr, gup->flags, pages + i,
nr = pin_user_pages(addr, nr, gup->gup_flags, pages + i,
NULL);
break;
case PIN_LONGTERM_BENCHMARK:
nr = pin_user_pages(addr, nr,
gup->flags | FOLL_LONGTERM,
gup->gup_flags | FOLL_LONGTERM,
pages + i, NULL);
break;
case DUMP_USER_PAGES_TEST:
if (gup->flags & GUP_TEST_FLAG_DUMP_PAGES_USE_PIN)
nr = pin_user_pages(addr, nr, gup->flags,
if (gup->test_flags & GUP_TEST_FLAG_DUMP_PAGES_USE_PIN)
nr = pin_user_pages(addr, nr, gup->gup_flags,
pages + i, NULL);
else
nr = get_user_pages(addr, nr, gup->flags,
nr = get_user_pages(addr, nr, gup->gup_flags,
pages + i, NULL);
break;
default:
Expand Down Expand Up @@ -187,7 +184,7 @@ static int __gup_test_ioctl(unsigned int cmd,

start_time = ktime_get();

put_back_pages(cmd, pages, nr_pages, gup->flags);
put_back_pages(cmd, pages, nr_pages, gup->test_flags);

end_time = ktime_get();
gup->put_delta_usec = ktime_us_delta(end_time, start_time);
Expand Down
3 changes: 2 additions & 1 deletion mm/gup_test.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,8 @@ struct gup_test {
__u64 addr;
__u64 size;
__u32 nr_pages_per_call;
__u32 flags;
__u32 gup_flags;
__u32 test_flags;
/*
* Each non-zero entry is the number of the page (1-based: first page is
* page 1, so that zero entries mean "do nothing") from the .addr base.
Expand Down
15 changes: 11 additions & 4 deletions tools/testing/selftests/vm/gup_test.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -37,13 +37,13 @@ int main(int argc, char **argv)
{
struct gup_test gup = { 0 };
unsigned long size = 128 * MB;
int i, fd, filed, opt, nr_pages = 1, thp = -1, repeats = 1, write = 0;
int i, fd, filed, opt, nr_pages = 1, thp = -1, repeats = 1, write = 1;
unsigned long cmd = GUP_FAST_BENCHMARK;
int flags = MAP_PRIVATE;
char *file = "/dev/zero";
char *p;

while ((opt = getopt(argc, argv, "m:r:n:F:f:abctTLUuwSH")) != -1) {
while ((opt = getopt(argc, argv, "m:r:n:F:f:abctTLUuwWSHp")) != -1) {
switch (opt) {
case 'a':
cmd = PIN_FAST_BENCHMARK;
Expand All @@ -65,9 +65,13 @@ int main(int argc, char **argv)
*/
gup.which_pages[0] = 1;
break;
case 'p':
/* works only with DUMP_USER_PAGES_TEST */
gup.test_flags |= GUP_TEST_FLAG_DUMP_PAGES_USE_PIN;
break;
case 'F':
/* strtol, so you can pass flags in hex form */
gup.flags = strtol(optarg, 0, 0);
gup.gup_flags = strtol(optarg, 0, 0);
break;
case 'm':
size = atoi(optarg) * MB;
Expand All @@ -93,6 +97,9 @@ int main(int argc, char **argv)
case 'w':
write = 1;
break;
case 'W':
write = 0;
break;
case 'f':
file = optarg;
break;
Expand Down Expand Up @@ -140,7 +147,7 @@ int main(int argc, char **argv)

gup.nr_pages_per_call = nr_pages;
if (write)
gup.flags |= FOLL_WRITE;
gup.gup_flags |= FOLL_WRITE;

fd = open("/sys/kernel/debug/gup_test", O_RDWR);
if (fd == -1) {
Expand Down

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