[PATCH v3 0/5] DRM scheduler kunit tests
Tvrtko Ursulin
tvrtko.ursulin at igalia.com
Thu Mar 6 14:56:26 UTC 2025
On 06/03/2025 12:37, Philipp Stanner wrote:
> On Tue, 2025-03-04 at 13:10 +0000, Tvrtko Ursulin wrote:
>> There has repeatedly been quite a bit of apprehension when any change
>> to the DRM
>> scheduler is proposed, with two main reasons being code base is
>> considered
>> fragile, not well understood and not very well documented, and
>> secondly the lack
>> of systematic testing outside the vendor specific tests suites and/or
>> test
>> farms.
>>
>> This series is an attempt to dislodge this status quo by adding some
>> unit tests
>> using the kunit framework.
>>
>> General approach is that there is a mock "hardware" backend which can
>> be
>> controlled from tests, which in turn allows exercising various
>> scheduler code
>> paths.
>>
>> Only some simple basic tests get added in the series and hopefully it
>> is easy to
>> understand what tests are doing.
>>
>> An obligatory "screenshot" for reference:
>>
>> [14:29:37] ============ drm_sched_basic_tests (3 subtests)
>> ============
>> [14:29:38] [PASSED] drm_sched_basic_submit
>> [14:29:38] ================== drm_sched_basic_test
>> ===================
>> [14:29:38] [PASSED] A queue of jobs in a single entity
>> [14:29:38] [PASSED] A chain of dependent jobs across multiple
>> entities
>> [14:29:38] [PASSED] Multiple independent job queues
>> [14:29:38] [PASSED] Multiple inter-dependent job queues
>> [14:29:38] ============== [PASSED] drm_sched_basic_test
>> ===============
>> [14:29:38] [PASSED] drm_sched_basic_entity_cleanup
>> [14:29:38] ============== [PASSED] drm_sched_basic_tests
>> ==============
>> [14:29:38] ======== drm_sched_basic_timeout_tests (1 subtest)
>> =========
>> [14:29:40] [PASSED] drm_sched_basic_timeout
>> [14:29:40] ========== [PASSED] drm_sched_basic_timeout_tests
>> ==========
>> [14:29:40] ======= drm_sched_basic_priority_tests (2 subtests)
>> ========
>> [14:29:42] [PASSED] drm_sched_priorities
>> [14:29:42] [PASSED] drm_sched_change_priority
>> [14:29:42] ========= [PASSED] drm_sched_basic_priority_tests
>> ==========
>> [14:29:42] ====== drm_sched_basic_modify_sched_tests (1 subtest)
>> ======
>> [14:29:43] [PASSED] drm_sched_test_modify_sched
>> [14:29:43] ======= [PASSED] drm_sched_basic_modify_sched_tests
>> ========
>> [14:29:43]
>> ============================================================
>> [14:29:43] Testing complete. Ran 10 tests: passed: 10
>> [14:29:43] Elapsed time: 13.330s total, 0.001s configuring, 4.005s
>> building, 9.276s running
>
> Yo,
>
> so I tried to test this all this in QEMU and I am encountering some
> explosions when I activate the scheduler tests. Just DRM tests boot
> fine.
>
> I'm using a kernel on relatively current drm-misc-next: 44d2f310f008
>
> I apply your series, then
> make defconfig
> make menuconfig # switch on kunit framework and scheduler tests
> install everything + initramfs
>
> Boot then causes errors as below. Just using the DRM kunit tests works
> fine.
>
> Excerpt of the first fault:
>
> [ 1.040513] # kunit_device: pass:3 fail:0 skip:0 total:3
> [ 1.040867] # Totals: pass:3 fail:0 skip:0 total:3
> [ 1.041296] ok 7 kunit_device
> [ 1.041936] KTAP version 1
> [ 1.042186] # Subtest: kunit_fault
> [ 1.042517] # module: kunit_test
> [ 1.042517] 1..1
> [ 1.043147] BUG: kernel NULL pointer dereference, address: 0000000000000000
> [ 1.043765] #PF: supervisor write access in kernel mode
> [ 1.044189] #PF: error_code(0x0002) - not-present page
> [ 1.044617] PGD 0 P4D 0
> [ 1.044818] Oops: Oops: 0002 [#1] PREEMPT SMP PTI
> [ 1.045380] CPU: 7 UID: 0 PID: 214 Comm: kunit_try_catch Tainted: G N 6.14.0-rc4-00387-g33e4632926a0 #8
> [ 1.046262] Tainted: [N]=TEST
> [ 1.046521] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-2.fc40 04/01/2014
> [ 1.047224] RIP: 0010:kunit_test_null_dereference+0x37/0x80
> [ 1.047706] Code: 80 b5 49 c7 c0 50 7f 56 b4 ba 01 00 00 00 65 48 8b 04 25 28 00 00 00 48 89 44 24 08 31 c0 48 8d 4c 24 07 48 c7 c6 80 8a 26 b5 <c7> 04 25 00 00 00 00 00 00 00 00 48 c7 87 70 01 00 00 a6 e9 8c b5
> [ 1.049204] RSP: 0000:ffffa609807c7ec8 EFLAGS: 00010246
> [ 1.049642] RAX: 0000000000000000 RBX: ffff91d982623000 RCX: ffffa609807c7ecf
> [ 1.050213] RDX: 0000000000000001 RSI: ffffffffb5268a80 RDI: ffffa60980013c68
> [ 1.050799] RBP: ffff91d98105afc0 R08: ffffffffb4567f50 R09: ffffffffb5807ce8
> [ 1.051375] R10: 0000000000000000 R11: 0000000000000001 R12: ffff91d98105afc0
> [ 1.051941] R13: ffff91d983c749c0 R14: ffffffffb45685e0 R15: ffff91d982623000
> [ 1.052543] FS: 0000000000000000(0000) GS:ffff91e48f9c0000(0000) knlGS:0000000000000000
> [ 1.053187] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 1.053649] CR2: 0000000000000000 CR3: 00000004cee30000 CR4: 00000000000006f0
> [ 1.054214] Call Trace:
> [ 1.054427] <TASK>
> [ 1.054597] ? __die+0x1e/0x60
> [ 1.054844] ? page_fault_oops+0x17b/0x4a0
> [ 1.055174] ? search_extable+0x26/0x30
> [ 1.055482] ? kunit_test_null_dereference+0x37/0x80
> [ 1.055888] ? search_module_extables+0x14/0x50
> [ 1.056255] ? exc_page_fault+0x6b/0x150
> [ 1.056571] ? asm_exc_page_fault+0x26/0x30
> [ 1.056898] ? __pfx_kunit_generic_run_threadfn_adapter+0x10/0x10
> [ 1.057387] ? __pfx_kunit_fail_assert_format+0x10/0x10
> [ 1.057799] ? kunit_test_null_dereference+0x37/0x80
> [ 1.058195] ? __kthread_parkme+0x33/0x80
> [ 1.058523] kunit_generic_run_threadfn_adapter+0x1c/0x40
> [ 1.058949] kthread+0xe9/0x1f0
> [ 1.059206] ? __pfx_kthread+0x10/0x10
> [ 1.059513] ret_from_fork+0x2f/0x50
> [ 1.059798] ? __pfx_kthread+0x10/0x10
> [ 1.060095] ret_from_fork_asm+0x1a/0x30
> [ 1.060421] </TASK>
> [ 1.060597] Modules linked in:
> [ 1.060841] CR2: 0000000000000000
> [ 1.061104] ---[ end trace 0000000000000000 ]---
> [ 1.061481] RIP: 0010:kunit_test_null_dereference+0x37/0x80
>
>
> I attach my kernel config and the full log file.
>
> What's awkward is that it does not seem to be related directly to
> sched, but only faults with sched.
>
>
> Could you try to reproduce this, Tvrtko?
Any chance that between the two runs you somehow manage to enable
CONFIG_KUNIT_FAULT_TEST?
Regards,
Tvrtko
>
>
> Thanks
> P.
>
>
>>
>> v2:
>> * Parameterize a bunch of similar tests.
>> * Improve test commentary.
>> * Rename TDR test to timeout. (Christian)
>> * Improve quality and consistency of naming. (Philipp)
>>
>> RFC v2 -> series v1:
>> * Rebased for drm_sched_init changes.
>> * Fixed modular build.
>> * Added some comments.
>> * Filename renames. (Philipp)
>>
>> v2:
>> * Dealt with a bunch of checkpatch warnings.
>>
>> v3:
>> * Some mock API renames, kerneldoc grammar fixes and indentation
>> fixes.
>>
>> Cc: Christian König <christian.koenig at amd.com>
>> Cc: Danilo Krummrich <dakr at kernel.org>
>> Cc: Matthew Brost <matthew.brost at intel.com>
>> Cc: Philipp Stanner <phasta at kernel.org>
>>
>> Tvrtko Ursulin (5):
>> drm: Move some options to separate new Kconfig
>> drm/scheduler: Add scheduler unit testing infrastructure and some
>> basic tests
>> drm/scheduler: Add a simple timeout test
>> drm/scheduler: Add basic priority tests
>> drm/scheduler: Add a basic test for modifying entities scheduler
>> list
>>
>> drivers/gpu/drm/Kconfig | 109 +----
>> drivers/gpu/drm/Kconfig.debug | 115 +++++
>> drivers/gpu/drm/scheduler/.kunitconfig | 12 +
>> drivers/gpu/drm/scheduler/Makefile | 2 +
>> drivers/gpu/drm/scheduler/tests/Makefile | 7 +
>> .../gpu/drm/scheduler/tests/mock_scheduler.c | 323 +++++++++++++
>> drivers/gpu/drm/scheduler/tests/sched_tests.h | 223 +++++++++
>> drivers/gpu/drm/scheduler/tests/tests_basic.c | 426
>> ++++++++++++++++++
>> 8 files changed, 1113 insertions(+), 104 deletions(-)
>> create mode 100644 drivers/gpu/drm/Kconfig.debug
>> create mode 100644 drivers/gpu/drm/scheduler/.kunitconfig
>> create mode 100644 drivers/gpu/drm/scheduler/tests/Makefile
>> create mode 100644 drivers/gpu/drm/scheduler/tests/mock_scheduler.c
>> create mode 100644 drivers/gpu/drm/scheduler/tests/sched_tests.h
>> create mode 100644 drivers/gpu/drm/scheduler/tests/tests_basic.c
>>
>
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