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[174.93.75.154]) by smtp.gmail.com with ESMTPSA id y29sm8958925qtm.13.2021.04.12.16.27.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 12 Apr 2021 16:27:57 -0700 (PDT) From: Peter Xu To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Andrea Arcangeli , peterx@redhat.com, Andrew Morton , Mike Rapoport , Axel Rasmussen Subject: [PATCH v2 2/5] userfaultfd/selftests: Remove the time() check on delayed uffd Date: Mon, 12 Apr 2021 19:27:50 -0400 Message-Id: <20210412232753.1012412-3-peterx@redhat.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20210412232753.1012412-1-peterx@redhat.com> References: <20210412232753.1012412-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Reviewed-by: Axel Rasmussen Signed-off-by: Peter Xu --- 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 ce23db8eec26..5cae66e27171 100644 --- a/tools/testing/selftests/vm/userfaultfd.c +++ b/tools/testing/selftests/vm/userfaultfd.c @@ -395,7 +395,6 @@ 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; @@ -432,7 +431,6 @@ 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) { @@ -495,12 +493,6 @@ 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