Let's test whether R/O long-term pinning is reliable for non-anonymous memory: when R/O long-term pinning a page, the expectation is that we break COW early before pinning, such that actual write access via the page tables won't break COW later and end up replacing the R/O-pinned page in the page table.
Consequently, R/O long-term pinning in private mappings would only target exclusive anonymous pages.
For now, all tests fail: # [RUN] R/O longterm GUP pin ... with shared zeropage not ok 151 Longterm R/O pin is reliable # [RUN] R/O longterm GUP pin ... with memfd not ok 152 Longterm R/O pin is reliable # [RUN] R/O longterm GUP pin ... with tmpfile not ok 153 Longterm R/O pin is reliable # [RUN] R/O longterm GUP pin ... with huge zeropage not ok 154 Longterm R/O pin is reliable # [RUN] R/O longterm GUP pin ... with memfd hugetlb (2048 kB) not ok 155 Longterm R/O pin is reliable # [RUN] R/O longterm GUP pin ... with memfd hugetlb (1048576 kB) not ok 156 Longterm R/O pin is reliable # [RUN] R/O longterm GUP-fast pin ... with shared zeropage not ok 157 Longterm R/O pin is reliable # [RUN] R/O longterm GUP-fast pin ... with memfd not ok 158 Longterm R/O pin is reliable # [RUN] R/O longterm GUP-fast pin ... with tmpfile not ok 159 Longterm R/O pin is reliable # [RUN] R/O longterm GUP-fast pin ... with huge zeropage not ok 160 Longterm R/O pin is reliable # [RUN] R/O longterm GUP-fast pin ... with memfd hugetlb (2048 kB) not ok 161 Longterm R/O pin is reliable # [RUN] R/O longterm GUP-fast pin ... with memfd hugetlb (1048576 kB) not ok 162 Longterm R/O pin is reliable
Signed-off-by: David Hildenbrand david@redhat.com --- tools/testing/selftests/vm/cow.c | 28 +++++++++++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/vm/cow.c b/tools/testing/selftests/vm/cow.c index 93c643bcdcf5..40ba45d0c6b4 100644 --- a/tools/testing/selftests/vm/cow.c +++ b/tools/testing/selftests/vm/cow.c @@ -534,6 +534,7 @@ static void test_iouring_fork(char *mem, size_t size) #endif /* LOCAL_CONFIG_HAVE_LIBURING */
enum ro_pin_test { + RO_PIN_TEST, RO_PIN_TEST_SHARED, RO_PIN_TEST_PREVIOUSLY_SHARED, RO_PIN_TEST_RO_EXCLUSIVE, @@ -566,6 +567,8 @@ static void do_test_ro_pin(char *mem, size_t size, enum ro_pin_test test, }
switch (test) { + case RO_PIN_TEST: + break; case RO_PIN_TEST_SHARED: case RO_PIN_TEST_PREVIOUSLY_SHARED: /* @@ -1150,6 +1153,16 @@ static void test_cow(char *mem, const char *smem, size_t size) free(old); }
+static void test_ro_pin(char *mem, const char *smem, size_t size) +{ + do_test_ro_pin(mem, size, RO_PIN_TEST, false); +} + +static void test_ro_fast_pin(char *mem, const char *smem, size_t size) +{ + do_test_ro_pin(mem, size, RO_PIN_TEST, true); +} + static void run_with_zeropage(non_anon_test_fn fn, const char *desc) { char *mem, *smem, tmp; @@ -1390,7 +1403,7 @@ struct non_anon_test_case { };
/* - * Test cases that target any pages in private mappings that are non anonymous: + * Test cases that target any pages in private mappings that are not anonymous: * pages that may get shared via COW ndependent of fork(). This includes * the shared zeropage(s), pagecache pages, ... */ @@ -1403,6 +1416,19 @@ static const struct non_anon_test_case non_anon_test_cases[] = { "Basic COW", test_cow, }, + /* + * Take a R/O longterm pin. When modifying the page via the page table, + * the page content change must be visible via the pin. + */ + { + "R/O longterm GUP pin", + test_ro_pin, + }, + /* Same as above, but using GUP-fast. */ + { + "R/O longterm GUP-fast pin", + test_ro_fast_pin, + }, };
static void run_non_anon_test_case(struct non_anon_test_case const *test_case)