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selftests/vm: cow: R/O long-term pinning reliability tests for non-anon pages

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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

Link: https://lkml.kernel.org/r/20221116102659.70287-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
David Hildenbrand 2022-11-16 11:26:42 +01:00 committed by Andrew Morton
parent f8664f3c4a
commit 97713a3abe
1 changed files with 27 additions and 1 deletions
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28
tools/testing/selftests/vm/cow.c
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@ -561,6 +561,7 @@ 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,
@ -593,6 +594,8 @@ 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:
/*
@ -1193,6 +1196,16 @@ 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;
@ -1433,7 +1446,7 @@ 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, ...
*/
@ -1446,6 +1459,19 @@ 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)