Hi,
kernelci.org [1] noticed a NULL pointer dereference during HDMI audio registration with linux-next-20190111 on Raspberry Pi using bcm2835_defconfig. I was able to reproduce it, but couldn't find anything suspicious in the commit ("Merge remote-tracking branch 'drm-misc-fixes/for-linux-next-fixes'") bisected by kernelci.org.
Best regards Stefan
[1] - https://kernelci.org/boot/id/5c383ceb59b514d9ca6edd2f/
[ 1.956798] Unable to handle kernel NULL pointer dereference at virtual address 00000000 [ 1.964895] pgd = (ptrval) [ 1.967682] [00000000] *pgd=00000000 [ 1.971272] Internal error: Oops: 17 [#1] ARM [ 1.975623] Modules linked in: [ 1.978684] CPU: 0 PID: 70 Comm: kworker/0:2 Not tainted 5.0.0-rc1 #1 [ 1.985111] Hardware name: BCM2835 [ 1.988540] Workqueue: events deferred_probe_work_func [ 1.993683] PC is at strcmp+0x10/0x40 [ 1.997358] LR is at soc_find_component+0x6c/0x78 [ 2.002055] pc : [] lr : [] psr: 60000013 [ 2.008310] sp : d9711bf0 ip : d9711c00 fp : d9711bfc [ 2.013523] r10: d975e100 r9 : d9713e20 r8 : 00000000 [ 2.018738] r7 : 00000000 r6 : 00000000 r5 : c0d566b8 r4 : d9760140 [ 2.025253] r3 : 00000032 r2 : 00000000 r1 : 00000000 r0 : d9759ec1 [ 2.031770] Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none [ 2.038893] Control: 00c5387d Table: 196c0008 DAC: 00000051 [ 2.044628] Process kworker/0:2 (pid: 70, stack limit = 0x(ptrval)) [ 2.050884] Stack: (0xd9711bf0 to 0xd9712000) [ 2.055239] 1be0: d9711c1c d9711c00 c05b06d8 c07f78b0 [ 2.063412] 1c00: d9713e20 00000000 00000000 d9713c4c d9711c44 d9711c20 c05b27b8 c05b0678 [ 2.071585] 1c20: d9713c4c d9713e20 00000000 d952f810 0000008c d9713e20 d9711c6c d9711c48 [ 2.079758] 1c40: c05b402c c05b2640 d975fd40 00000000 d9713c4c d952f810 d952f800 c0d45c38 [ 2.087931] 1c60: d9711c8c d9711c70 c05c1190 c05b3f04 d9713c40 00000000 d952f810 d952f810 [ 2.096105] 1c80: d9711cdc d9711c90 c0481e48 c05c1158 00000000 d96d37c0 d9756e80 c0d08048 [ 2.104277] 1ca0: 00000000 0000000c 00000000 da68af2b d9711cdc d96d37c0 d9756e80 d952fe10 [ 2.112450] 1cc0: 00000000 00000000 d9713400 006000c0 d9711d14 d9711ce0 c0489f4c c0481b80 [ 2.120622] 1ce0: d952fe10 c0480224 d9711d14 d9713400 00000000 d952fe10 00000008 d96d55c0 [ 2.128796] 1d00: d9759000 c0d460d0 d9711d34 d9711d18 c0479acc c0489e18 d96d37c0 d9759000 [ 2.136969] 1d20: d96a580c 00000008 d9711d74 d9711d38 c04899cc c0479a48 00000018 c0232354 [ 2.145142] 1d40: d952fc10 c04797e0 c0d460bc d9759000 c0d460c8 c093a284 d96d37c0 00000000 [ 2.153315] 1d60: 00000000 00000000 d9711d94 d9711d78 c0489af0 c04897f0 d952fc10 00000000 [ 2.161488] 1d80: c0d46070 c0d46070 d9711da4 d9711d98 c0486ef0 c0489a3c d9711dc4 d9711da8 [ 2.169662] 1da0: c04921ac c0486edc d952fc10 c0e340e4 c0e340e0 c0d46070 d9711e04 d9711dc8 [ 2.177836] 1dc0: c04902d0 c0492160 d9711e8c d952fc10 d952fcd8 00000007 d9711e04 d952fc10 [ 2.186009] 1de0: c0d46070 c0d46070 d9711e8c 00000001 00000000 c0d46238 d9711e34 d9711e08 [ 2.194183] 1e00: c04907d4 c0490088 d9711e34 d9711e18 00000001 d952fc10 c0d46070 d9711e8c [ 2.202355] 1e20: 00000001 00000000 d9711e54 d9711e38 c0490a18 c0490648 c0d08048 d9711e8c [ 2.210529] 1e40: c0490968 00000000 d9711e84 d9711e58 c048e338 c0490974 d9711e84 d94ac4dc [ 2.218703] 1e60: d96d54b4 da68af2b d952fc10 c0d46440 c0d08048 d952fc44 d9711ebc d9711e88 [ 2.226876] 1e80: c0490528 c048e294 c048ad30 d952fc10 00000001 da68af2b 00000000 c0d46214 [ 2.235049] 1ea0: c0d46440 d952fc10 d9c58300 00000000 d9711ecc d9711ec0 c0490a88 c0490470 [ 2.243222] 1ec0: d9711eec d9711ed0 c048f268 c0490a78 c0d46214 d952fc10 c0d46228 d9c58300 [ 2.251395] 1ee0: d9711f0c d9711ef0 c048f844 c048f23c d96eda80 c0d46234 c0d102c0 d9c58300 [ 2.259569] 1f00: d9711f44 d9711f10 c0135388 c048f7c4 c0d175a0 c0d102d4 c0d0ff7c d96eda80 [ 2.267742] 1f20: c0d102c0 c0d102c0 c0d175a0 c0d102d4 d96eda94 00000008 d9711f74 d9711f48 [ 2.275915] 1f40: c013620c c01351a0 00000000 d96fd080 d96f2900 d9710000 00000000 d96eda80 [ 2.284089] 1f60: c0135f80 d94e1e88 d9711fac d9711f78 c013aa00 c0135f8c d96fd098 d96fd098 [ 2.292261] 1f80: d9711fac d96f2900 c013a8bc 00000000 00000000 00000000 00000000 00000000 [ 2.300432] 1fa0: 00000000 d9711fb0 c01010e8 c013a8c8 00000000 00000000 00000000 00000000 [ 2.308602] 1fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 [ 2.316773] 1fe0: 00000000 00000000 00000000 00000000 00000013 00000000 00000000 00000000 [ 2.324930] Backtrace: [ 2.327392] [] (strcmp) from [] (soc_find_component+0x6c/0x78) [ 2.334969] [] (soc_find_component) from [] (soc_init_dai_link+0x184/0x1f0) [ 2.343659] r7:d9713c4c r6:00000000 r5:00000000 r4:d9713e20 [ 2.349323] [] (soc_init_dai_link) from [] (snd_soc_register_card+0x134/0x180) [ 2.358276] r9:d9713e20 r8:0000008c r7:d952f810 r6:00000000 r5:d9713e20 r4:d9713c4c [ 2.366030] [] (snd_soc_register_card) from [] (devm_snd_soc_register_card+0x44/0x78) [ 2.375591] r9:c0d45c38 r8:d952f800 r7:d952f810 r6:d9713c4c r5:00000000 r4:d975fd40 [ 2.383350] [] (devm_snd_soc_register_card) from [] (vc4_hdmi_bind+0x2d4/0x538) [ 2.392386] r7:d952f810 r6:d952f810 r5:00000000 r4:d9713c40 [ 2.398049] [] (vc4_hdmi_bind) from [] (component_bind_all+0x140/0x22c) [ 2.406396] r10:006000c0 r9:d9713400 r8:00000000 r7:00000000 r6:d952fe10 r5:d9756e80 [ 2.414209] r4:d96d37c0 [ 2.416748] [] (component_bind_all) from [] (vc4_drm_bind+0x90/0x10c) [ 2.424921] r10:c0d460d0 r9:d9759000 r8:d96d55c0 r7:00000008 r6:d952fe10 r5:00000000 [ 2.432733] r4:d9713400 [ 2.435271] [] (vc4_drm_bind) from [] (try_to_bring_up_master+0x1e8/0x24c) [ 2.443872] r7:00000008 r6:d96a580c r5:d9759000 r4:d96d37c0 [ 2.449529] [] (try_to_bring_up_master) from [] (component_add+0xc0/0x120) [ 2.458134] r10:00000000 r9:00000000 r8:00000000 r7:d96d37c0 r6:c093a284 r5:c0d460c8 [ 2.465947] r4:d9759000 [ 2.468483] [] (component_add) from [] (vc4_v3d_dev_probe+0x20/0x28) [ 2.476564] r7:c0d46070 r6:c0d46070 r5:00000000 r4:d952fc10 [ 2.482224] [] (vc4_v3d_dev_probe) from [] (platform_drv_probe+0x58/0xa4) [ 2.490751] [] (platform_drv_probe) from [] (really_probe+0x254/0x3e8) [ 2.499007] r7:c0d46070 r6:c0e340e0 r5:c0e340e4 r4:d952fc10 [ 2.504668] [] (really_probe) from [] (driver_probe_device+0x198/0x1c0) [ 2.513013] r10:c0d46238 r9:00000000 r8:00000001 r7:d9711e8c r6:c0d46070 r5:c0d46070 [ 2.520826] r4:d952fc10 [ 2.523364] [] (driver_probe_device) from [] (__device_attach_driver+0xb0/0x104) [ 2.532489] r9:00000000 r8:00000001 r7:d9711e8c r6:c0d46070 r5:d952fc10 r4:00000001 [ 2.540228] [] (__device_attach_driver) from [] (bus_for_each_drv+0xb0/0xc4) [ 2.549002] r7:00000000 r6:c0490968 r5:d9711e8c r4:c0d08048 [ 2.554661] [] (bus_for_each_drv) from [] (__device_attach+0xc4/0x15c) [ 2.562916] r7:d952fc44 r6:c0d08048 r5:c0d46440 r4:d952fc10 [ 2.568573] [] (__device_attach) from [] (device_initial_probe+0x1c/0x20) [ 2.577090] r8:00000000 r7:d9c58300 r6:d952fc10 r5:c0d46440 r4:c0d46214 [ 2.583788] [] (device_initial_probe) from [] (bus_probe_device+0x38/0x90) [ 2.592395] [] (bus_probe_device) from [] (deferred_probe_work_func+0x8c/0xb0) [ 2.601343] r7:d9c58300 r6:c0d46228 r5:d952fc10 r4:c0d46214 [ 2.607013] [] (deferred_probe_work_func) from [] (process_one_work+0x1f4/0x378) [ 2.616135] r7:d9c58300 r6:c0d102c0 r5:c0d46234 r4:d96eda80 [ 2.621795] [] (process_one_work) from [] (worker_thread+0x28c/0x404) [ 2.629968] r10:00000008 r9:d96eda94 r8:c0d102d4 r7:c0d175a0 r6:c0d102c0 r5:c0d102c0 [ 2.637781] r4:d96eda80 [ 2.640320] [] (worker_thread) from [] (kthread+0x144/0x15c) [ 2.647712] r10:d94e1e88 r9:c0135f80 r8:d96eda80 r7:00000000 r6:d9710000 r5:d96f2900 [ 2.655527] r4:d96fd080 r3:00000000 [ 2.659104] [] (kthread) from [] (ret_from_fork+0x14/0x2c) [ 2.666313] Exception stack(0xd9711fb0 to 0xd9711ff8) [ 2.671358] 1fa0: 00000000 00000000 00000000 00000000 [ 2.679528] 1fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 [ 2.687696] 1fe0: 00000000 00000000 00000000 00000000 00000013 00000000 [ 2.694307] r10:00000000 r9:00000000 r8:00000000 r7:00000000 r6:00000000 r5:c013a8bc [ 2.702120] r4:d96f2900 [ 2.704657] Code: e1a0c00d e92dd800 e24cb004 e4d03001 (e4d12001) [ 2.710866] ---[ end trace 5b8299805fe2083c ]---