On Wed, Dec 17, 2025 at 08:47:57PM +0530, Ojaswin Mujoo wrote: > Hello, > > While writing some Kunit tests for ext4 filesystem, I'm encountering an > issue in the way we display the diagnostic logs upon failures, when > using KUNIT_CASE_PARAM() to write the tests. > > This can be observed by patching fs/ext4/mballoc-test.c to fail > and print one of the params: > > --- a/fs/ext4/mballoc-test.c > +++ b/fs/ext4/mballoc-test.c > @@ -350,6 +350,8 @@ static int mbt_kunit_init(struct kunit *test) > struct super_block *sb; > int ret; > > + KUNIT_FAIL(test, "Failed: blocksize_bits=%d", layout->blocksize_bits); > + > sb = mbt_ext4_alloc_super_block(); > if (sb == NULL) > return -ENOMEM; > > With the above change, we can observe the following output (snipped): > > [18:50:25] ============== ext4_mballoc_test (7 subtests) ============== > [18:50:25] ================= test_new_blocks_simple ================== > [18:50:25] [FAILED] block_bits=10 cluster_bits=3 blocks_per_group=8192 > group_count=4 desc_size=64 > [18:50:25] # test_new_blocks_simple: EXPECTATION FAILED at > fs/ext4/mballoc-test.c:364 > [18:50:25] Failed: blocksize_bits=12 > [18:50:25] [FAILED] block_bits=12 cluster_bits=3 blocks_per_group=8192 > group_count=4 desc_size=64 > [18:50:25] # test_new_blocks_simple: EXPECTATION FAILED at > fs/ext4/mballoc-test.c:364 > [18:50:25] Failed: blocksize_bits=16 > [18:50:25] [FAILED] block_bits=16 cluster_bits=3 blocks_per_group=8192 > group_count=4 desc_size=64 > [18:50:25] # test_new_blocks_simple: EXPECTATION FAILED at > fs/ext4/mballoc-test.c:364 > [18:50:25] Failed: blocksize_bits=10 > [18:50:25] # test_new_blocks_simple: pass:0 fail:3 skip:0 total:3 > [18:50:25] ============= [FAILED] test_new_blocks_simple ============== > <snip> > > Note that the diagnostic logs don't show up correctly. Ideally they > should be before test result but here the first [FAILED] test has no > logs printed above whereas the last "Failed: blocksize_bits=10" print > comes after the last subtest, when it actually corresponds to the first > subtest. > > The KTAP file itself seems to have diagnostic logs in the right place: > > KTAP version 1 > 1..2 > KTAP version 1 > # Subtest: ext4_mballoc_test > # module: ext4 > 1..7 > KTAP version 1 > # Subtest: test_new_blocks_simple
So looking into this a bit more and comparing the parameterized output with non parameterized output, I'm seeing that the difference is that output via KUNIT_CASE_PARAM is not printing the test plan line right here. This plan sort of serves as divider between the parent and the 3 children's logs and without it our parsing logic gets confused. When I manually added a "1..3" test plan I could see the parsing work correctly without any changes to kunit_parser.py. Regards, ojaswin > # test_new_blocks_simple: EXPECTATION FAILED at fs/ext4/mballoc-test.c:364 > Failed: blocksize_bits=10 > not ok 1 block_bits=10 cluster_bits=3 blocks_per_group=8192 > group_count=4 desc_size=64 > # test_new_blocks_simple: EXPECTATION FAILED at fs/ext4/mballoc-test.c:364 > Failed: blocksize_bits=12 > not ok 2 block_bits=12 cluster_bits=3 blocks_per_group=8192 > group_count=4 desc_size=64 > # test_new_blocks_simple: EXPECTATION FAILED at fs/ext4/mballoc-test.c:364 > Failed: blocksize_bits=16 > not ok 3 block_bits=16 cluster_bits=3 blocks_per_group=8192 > group_count=4 desc_size=64 > # test_new_blocks_simple: pass:0 fail:3 skip:0 total:3 > not ok 1 test_new_blocks_simple > <snip> > > By tracing kunit_parser.py script, I could see the issue here is in the > parsing of the "Subtest: test_new_blocks_simple". We end up associating > everything below the subtest till "not ok 1 block_bits=10..." as > diagnostic logs of the subtest, while these lons actually belong to the > first of the 3 subtests under this test. >
