The patch titled
Subject: selftests: line buffer test program's stdout
has been added to the -mm mm-unstable branch. Its filename is
selftests-line-buffer-test-programs-stdout.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftests-line-buffer-test-programs-stdout.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Ryan Roberts <ryan.roberts@xxxxxxx>
Subject: selftests: line buffer test program's stdout
Date: Mon, 24 Jul 2023 09:25:15 +0100
Patch series "selftests/mm fixes for arm64", v3.
This patch (of 8):
The selftests runner pipes the test program's stdout to tap_prefix. The
presence of the pipe means that the test program sets its stdout to be
fully buffered (as aposed to line buffered when directly connected to the
terminal). The block buffering means that there is often content in the
buffer at fork() time, which causes the output to end up duplicated. This
was causing problems for mm:cow where test results were duplicated 20-30x.
Solve this by using `stdbuf`, when available to force the test program to
use line buffered mode. This means previously printf'ed results are
flushed out of the program before any fork().
Additionally, explicitly set line buffer mode in ksft_print_header(),
which means that all test programs that use the ksft framework will
benefit even if stdbuf is not present on the system.
Link: https://lkml.kernel.org/r/20230724082522.1202616-1-ryan.roberts@xxxxxxx
Link: https://lkml.kernel.org/r/20230724082522.1202616-2-ryan.roberts@xxxxxxx
Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx>
Reviewed-by: Mark Brown <broonie@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Florent Revest <revest@xxxxxxxxxxxx>
Cc: Jérôme Glisse <jglisse@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
tools/testing/selftests/kselftest.h | 9 +++++++++
tools/testing/selftests/kselftest/runner.sh | 7 +++++--
2 files changed, 14 insertions(+), 2 deletions(-)
--- a/tools/testing/selftests/kselftest.h~selftests-line-buffer-test-programs-stdout
+++ a/tools/testing/selftests/kselftest.h
@@ -113,6 +113,15 @@ static inline int ksft_get_error_cnt(voi
static inline void ksft_print_header(void)
{
+ /*
+ * Force line buffering; If stdout is not connected to a terminal, it
+ * will otherwise default to fully buffered, which can cause output
+ * duplication if there is content in the buffer when fork()ing. If
+ * there is a crash, line buffering also means the most recent output
+ * line will be visible.
+ */
+ setvbuf(stdout, NULL, _IOLBF, 0);
+
if (!(getenv("KSFT_TAP_LEVEL")))
printf("TAP version 13\n");
}
--- a/tools/testing/selftests/kselftest/runner.sh~selftests-line-buffer-test-programs-stdout
+++ a/tools/testing/selftests/kselftest/runner.sh
@@ -105,15 +105,18 @@ run_one()
echo "# Warning: file $TEST is missing!"
echo "not ok $test_num $TEST_HDR_MSG"
else
+ if [ -x /usr/bin/stdbuf ]; then
+ stdbuf="/usr/bin/stdbuf --output=L "
+ fi
eval kselftest_cmd_args="\$${kselftest_cmd_args_ref:-}"
- cmd="./$BASENAME_TEST $kselftest_cmd_args"
+ cmd="$stdbuf ./$BASENAME_TEST $kselftest_cmd_args"
if [ ! -x "$TEST" ]; then
echo "# Warning: file $TEST is not executable"
if [ $(head -n 1 "$TEST" | cut -c -2) = "#!" ]
then
interpreter=$(head -n 1 "$TEST" | cut -c 3-)
- cmd="$interpreter ./$BASENAME_TEST"
+ cmd="$stdbuf $interpreter ./$BASENAME_TEST"
else
echo "not ok $test_num $TEST_HDR_MSG"
return
_
Patches currently in -mm which might be from ryan.roberts@xxxxxxx are
mm-allow-deferred-splitting-of-arbitrary-large-anon-folios.patch
mm-implement-folio_remove_rmap_range.patch
mm-batch-zap-large-anonymous-folio-pte-mappings.patch
selftests-line-buffer-test-programs-stdout.patch
selftests-mm-skip-soft-dirty-tests-on-arm64.patch
selftests-mm-enable-mrelease_test-for-arm64.patch
selftests-mm-fix-thuge-gen-test-bugs.patch
selftests-mm-va_high_addr_switch-should-skip-unsupported-arm64-configs.patch
selftests-mm-make-migration-test-robust-to-failure.patch
selftests-mm-optionally-pass-duration-to-transhuge-stress.patch
selftests-mm-run-all-tests-from-run_vmtestssh.patch
