On 3/13/24 7:58 PM, Joey Gouly wrote:
> Hi Muhammad,
>
> On Thu, Jan 25, 2024 at 08:46:07PM +0500, Muhammad Usama Anjum wrote:
>> Save and restore nr_hugepages before changing it during the test. A test
>> should not change system wide settings.
>>
>> Fixes: 5f23f6d082a9 ("x86/pkeys: Add self-tests")
>> Signed-off-by: Muhammad Usama Anjum <usama.an...@collabora.com>
>> ---
>> tools/testing/selftests/mm/protection_keys.c | 34 ++++++++++++++++++++
>> 1 file changed, 34 insertions(+)
>>
>> diff --git a/tools/testing/selftests/mm/protection_keys.c
>> b/tools/testing/selftests/mm/protection_keys.c
>> index 48dc151f8fca8..f822ae31af22e 100644
>> --- a/tools/testing/selftests/mm/protection_keys.c
>> +++ b/tools/testing/selftests/mm/protection_keys.c
>> @@ -54,6 +54,7 @@ int test_nr;
>> u64 shadow_pkey_reg;
>> int dprint_in_signal;
>> char dprint_in_signal_buffer[DPRINT_IN_SIGNAL_BUF_SIZE];
>> +char buf[256];
>>
>> void cat_into_file(char *str, char *file)
>> {
>> @@ -1744,6 +1745,38 @@ void pkey_setup_shadow(void)
>> shadow_pkey_reg = __read_pkey_reg();
>> }
>>
>> +void restore_settings_atexit(void)
>> +{
>> + cat_into_file(buf, "/proc/sys/vm/nr_hugepages");
>> +}
>> +
>> +void save_settings(void)
>> +{
>> + int fd;
>> + int err;
>> +
>> + if (geteuid())
>> + return;
>> +
>> + fd = open("/proc/sys/vm/nr_hugepages", O_RDONLY);
>> + if (fd < 0) {
>> + fprintf(stderr, "error opening\n");
>> + perror("error: ");
>> + exit(__LINE__);
>> + }
>> +
>> + /* -1 to guarantee leaving the trailing \0 */
>> + err = read(fd, buf, sizeof(buf)-1);
>> + if (err < 0) {
>> + fprintf(stderr, "error reading\n");
>> + perror("error: ");
>> + exit(__LINE__);
>> + }
>> +
>> + atexit(restore_settings_atexit);
>> + close(fd);
>> +}
>> +
>> int main(void)
>> {
>> int nr_iterations = 22;
>> @@ -1751,6 +1784,7 @@ int main(void)
>>
>> srand((unsigned int)time(NULL));
>>
>> + save_settings();
>> setup_handlers();
>>
>> printf("has pkeys: %d\n", pkeys_supported);
>> --
>> 2.42.0
>>
>
> This break the tests for me:
>
> assert() at protection_keys.c::812 test_nr: 19 iteration: 1
> running abort_hooks()...
>
> This is because some of the tests fork, so on their atexit() they will set the
> nr_hugepages back to the previous setting. Specifically the
> test_pkey_alloc_exhaust() test.
Thank you for reporting. Please can you test the following patch:
--- a/tools/testing/selftests/mm/protection_keys.c
+++ b/tools/testing/selftests/mm/protection_keys.c
@@ -1745,9 +1745,12 @@ void pkey_setup_shadow(void)
shadow_pkey_reg = __read_pkey_reg();
}
+pid_t parent_pid;
+
void restore_settings_atexit(void)
{
- cat_into_file(buf, "/proc/sys/vm/nr_hugepages");
+ if (parent_pid == getpid())
+ cat_into_file(buf, "/proc/sys/vm/nr_hugepages");
}
void save_settings(void)
@@ -1773,6 +1776,7 @@ void save_settings(void)
exit(__LINE__);
}
+ parent_pid = getpid();
atexit(restore_settings_atexit);
close(fd);
}
>
> Thanks,
> Joey
>
--
BR,
Muhammad Usama Anjum
