[PATCH 2/5] userfaultfd/selftests: Remove the time() check on delayed uffd

From: Peter Xu
Date: Tue Mar 09 2021 - 19:46:04 EST


There seems to have no guarantee that time() will return the same for the two
calls even if there's no delay, e.g. when a fault is accidentally crossing the
changing of a second. Meanwhile, this message is also not helping that much
since delay could happen with a lot of reasons, e.g., schedule latency of
resolving thread. It may not mean an issue with uffd.

Neither do I saw this error triggered either in the past runs. Even if it
triggers, it'll be drown in all the rest of test logs. Remove it.

Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
---
tools/testing/selftests/vm/userfaultfd.c | 8 --------
1 file changed, 8 deletions(-)

diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c
index 6dab8ef034a0..5cde062f07bc 100644
--- a/tools/testing/selftests/vm/userfaultfd.c
+++ b/tools/testing/selftests/vm/userfaultfd.c
@@ -568,7 +568,6 @@ static void *locking_thread(void *arg)
unsigned long long count;
char randstate[64];
unsigned int seed;
- time_t start;

if (bounces & BOUNCE_RANDOM) {
seed = (unsigned int) time(NULL) - bounces;
@@ -605,7 +604,6 @@ static void *locking_thread(void *arg)
page_nr += 1;
page_nr %= nr_pages;

- start = time(NULL);
if (bounces & BOUNCE_VERIFY) {
count = *area_count(area_dst, page_nr);
if (!count) {
@@ -668,12 +666,6 @@ static void *locking_thread(void *arg)
count++;
*area_count(area_dst, page_nr) = count_verify[page_nr] = count;
pthread_mutex_unlock(area_mutex(area_dst, page_nr));
-
- if (time(NULL) - start > 1)
- fprintf(stderr,
- "userfault too slow %ld "
- "possible false positive with overcommit\n",
- time(NULL) - start);
}

return NULL;
--
2.26.2