Regression: memory corruption on Atmel SAMA5D31

[Peter Rosin]

2022-06-20 at 16:22, Tudor.Ambarus at microchip.com wrote:
> 
>>
>> git at github.com:ambarus/linux-0day.git, branch dma-regression-hdmac-v5.18-rc7-4th-attempt
>>
> 
> Hi, Peter,
> 
> I've just forced pushed on this branch, I had a typo somewhere and with that fixed I could
> no longer reproduce the bug. Tested for ~20 minutes. Would you please test last 3 patches
> and tell me if you can still reproduce the bug?

Hi!

I rebased your patches onto my current branch which is v5.18.2 plus a few unrelated
changes (at least they are unrelated after removing the previous workaround to disable
nand-dma entirely).

The unrelated patches are two backports so that drivers recognize new compatibles [1][2],
which should be completely harmless, plus a couple of proposed fixes that happens to fix
eeprom issues with the at91 I2C driver from Codrin Ciubotariu [3].

On that kernel, I can still reproduce. It seems a bit harder to reproduce the problem now
though. If the system is otherwise idle, the sha256sum test did not reproduce in a run of
150+ attempts, but if I let the "real" application run while I do the test, I get a failure rate
of about 10%, see below. The real application burns some CPU (but not all of it) and
communicates with HW using I2C, native UARTs and two of the four USB-serial ports
(FTDI, with the latency set to 1ms as mentioned earlier), so I guess there is more DMA
pressure or something? There is a 100mbps network connection, but it was left "idle"
during this test.

Cheers,
Peter

$ dd if=/dev/urandom of=testfile bs=1024 count=40000
40000+0 records in
40000+0 records out
40960000 bytes (41 MB, 39 MiB) copied, 80.0485 s, 512 kB/s
$ while :; do cat testfile | sha256sum; done
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
a4850c1bb0226f14659035cdf1461c7df03d50bff8af560e3bd204942556b73f  -
43c1941e15bd7e048e9d5f1d41ce67517cb6e59dae1d3af256d1507168100fcb  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
4a35af384455853a24b943ef94353663e8c22a9aa29d2e275194fd544d0b194a  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
f6710849b36e6954c26ff62cd974ecb082b93fa6e53ecf0aea7e0c93acc0a445  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
2c2f4ac91f435439d2d640c34ee89b4d1ebf3adb8438efbf064a4139247241c5  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
b93e0c56cfba75cb9e2b35ff6769abdb6c1a5d17cadc28cec1979188e044cf3d  -
^C

[1] https://lore.kernel.org/linux-kernel/42db911c-5eba-0511-3e8c-8011a2a5b44a@axentia.se/
[2] https://lore.kernel.org/linux-kernel/ea4cd16b-4a04-8857-d08a-53be58b00d28@axentia.se/
[3] https://lore.kernel.org/linux-kernel/20220614101347.16910-1-codrin.ciubotariu@microchip.com/