On 22.07.2020 12:59, Bruno Thomsen wrote:
> Hi Andrew,
>
>>>> I have been having issues with Ethernet PHY type ID
>>>> auto-detection when changing from the deprecated fec
>>>> phy-reset-{gpios,duration,post-delay} properties to the
>>>> modern mdio reset-{assert-us,deassert-us,gpios}
>>>> properties in the device tree.
>>
>>>> Kernel error messages (modem mdio reset):
>>>> mdio_bus 30be0000.ethernet-1: MDIO device at address 1 is missing.
>>>> fec 30be0000.ethernet eth0: Unable to connect to phy
>>
>> It sounds like the PHY is not responding during scanning of the bus.
>
> Yes, that is correct.
>
>> If the ID is mostly 0xff there is no device there.
>>
>> So check the initial reset state of the PHY, and when is it taken out
>> of reset, and is the delay long enough for it to get itself together
>> and start answering requests.
>
> When capturing traces with a logic analyzer, I do the following:
> - break the target in the bootloader
> - start trigger on reset or mdio signal (had to use mdio as reset wasn't used)
> - boot linux
>
> I monitor 4 signals: MDIO, MDC, 3V3, reset.
>
> The new mdio code path does not reset the PHY before reading
> of PHY type ID and for some reason this result in no responce,
> e.g. high (0xFFFF) and missing MDIO turnaround.
>
> MDC is 2.5MHz, and I can decode the 2 read requests with a logic
> analyzer:
>
> START C22
> OPCODE [Read]
> PHY Address ['1' (0x01)]
> Register Address ['2' (0x02)]
> !Turnaround
> Data ['65535' (0xFFFF)]
>
> START C22
> OPCODE [Read]
> PHY Address ['1' (0x01)]
> Register Address ['3' (0x03)]
> !Turnaround
> Data ['65535' (0xFFFF)]
>
> When using the deprecated fec phy reset code path, the PHY
> chip is reset just before reading of register 0x02 and 0x03.
> In this case the PHY respond correct with 0x0022 and 0x1561.
>
> When looking at the mdio code I don't understand how the
> reset code should even work in the first place.
>
>> static int mdio_probe(struct device *dev)
>> {
>> struct mdio_device *mdiodev = to_mdio_device(dev);
>> struct device_driver *drv = mdiodev->dev.driver;
>> struct mdio_driver *mdiodrv = to_mdio_driver(drv);
>> int err = 0;
>>
>> if (mdiodrv->probe) {
>> /* Deassert the reset signal */
>> mdio_device_reset(mdiodev, 0);
>
> This assumes that the reset signal is asserted already.
> Not my case and it seems very flaky.
>
> Deprecated fec code assert reset signal before reset assert delay,
> following deassert reset and deassert delay.
> https://elixir.bootlin.com/linux/latest/source/drivers/net/ethernet/freescale/fec_main.c#L3373
>
>>
>> err = mdiodrv->probe(mdiodev);
>> if (err) {
>> /* Assert the reset signal */
>> mdio_device_reset(mdiodev, 1);
>
> Reset signal is asserted in error path but there are no
> retry on probe.
>
>
>> void mdio_device_reset(struct mdio_device *mdiodev, int value)
>> {
>> unsigned int d;
>>
>> ......
>>
>> d = value ? mdiodev->reset_assert_delay : mdiodev->reset_deassert_delay;
>> if (d)
>> usleep_range(d, d + max_t(unsigned int, d / 10, 100));
>
> This is not the recommended way of sleeping if d > 20ms.
>
Meanwhile there's a helper fsleep() that considers the thresholds for calling
udelay/usleep_range/msleep.
> https://www.kernel.org/doc/Documentation/timers/timers-howto.txt
>
> The deprecated fec code handles this correctly.
> https://elixir.bootlin.com/linux/latest/source/drivers/net/ethernet/freescale/fec_main.c#L3381
>
> if (d)
> if (d > 20000)
> msleep(d / 1000);
> else
> usleep_range(d, d + max_t(unsigned int, d / 10, 100));
>
>
> Micrel recommended reset circuit has a deassert tau of 100ms, e.g. 10k * 10uF.
> So to be sure the signal is deasserted 5 * tau or more, and this brings the
> value
> up in the 500-1000ms range depending on component tolerances and design
> margin.
>
> See figure 22 in pdf for reset circuit.
> http://ww1.microchip.com/downloads/en/devicedoc/ksz8081mnx-rnb.pdf
>
> So my current conclusion is that using generic mdio phy handling does
> not work with Micrel PHYs unless 3 issues has been resolved.
> - Reset PHY before auto type detection.
> - Add initial assert reset signal + delay when resetting phy.
> - Handle >20ms reset delays.
>
> /Bruno
>
> ----
> When using the 5.8.0-rc6 kernel (dirty due to device tree changes),
> I sometimes hit this kernel issue (never seen it with 5.7.8 or earlier),
> but don't think it's related:
>
> kernel:
> =============================================================================
> kernel: BUG task_struct(119:NetworkManager-dispatcher.service) (Not tainted):
> Poison overwritten
> kernel:
> -----------------------------------------------------------------------------
> kernel: Disabling lock debugging due to kernel taint
> kernel: INFO: 0xe05e9b3f-0x9b36c418 @offset=30464. First byte 0xff instead of
> 0x6b
> kernel: INFO: Slab 0xaa165da6 objects=18 used=0 fp=0x37e5d9c3 flags=0x10200
> kernel: INFO: Object 0xf19b9dd9 @offset=29440 fp=0x00000000
> kernel: Redzone cb135af3: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
> ................
> kernel: Redzone a0061a8a: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
> ................
> kernel: Redzone f2917653: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
> ................
> kernel: Redzone aeb00bb5: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
> ................
> kernel: Object f19b9dd9: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object cadb3eab: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object a51c2cd1: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 6b25d1e5: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 1e35e7e8: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object aea2a999: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object e160fc75: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object c1c29834: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 17ff6205: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object a6781094: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object ce2fd05e: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 7daa8dfb: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 4c0e09e9: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object b23b73b7: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 698ecfeb: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object c0437471: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object a9236eff: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 4a6eac62: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 7fda2c51: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 8f143bf4: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object aaa2bfdd: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 22d54b92: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 8fcef107: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object d2a1c8a9: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object b25c8021: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 1bed0f85: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object a6c9ddc2: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 306f6960: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 478e89fc: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 90f8a983: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 0d8a4733: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 254b16da: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 409e6dac: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object d043695a: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object abee8a24: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 18715fa9: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object fb3630b3: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 3aaedaf7: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 32565782: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 26869f35: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 789a34f9: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 8865b386: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object a0d7868e: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 9cd04fce: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 4214b445: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 9d69b597: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 845ea8c4: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 2c937a0b: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object eb5293e8: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object dab824c2: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object bfa6c2fa: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object a2c4a8be: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 5e1f207c: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object a974428f: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 91af2a44: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 6f71ee6f: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object d4abc42d: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 3737f8db: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 65bd39e9: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object cd12758c: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 212096ca: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 8462745b: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object a430d1b2: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 7a0d1289: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object e05e9b3f: ff 4d ff ff ff ff ff ff 10 e7 c6 77 3e 38 08 00
> .M.........w>8..
> kernel: Object 8c5945af: 45 00 00 48 42 05 00 00 80 11 75 5c ac 14 15 1c
> E..HB.....u\....
> kernel: Object de1b76ee: ac 14 15 ff e1 15 e1 15 00 34 8a 61 53 70 6f 74
> .........4.aSpot
> kernel: Object a54d91d1: 55 64 70 30 94 e4 06 54 2b ed 49 66 00 01 00 04
> Udp0...T+.If....
> kernel: Object 08ebc3be: 48 95 c2 03 94 eb 5d 89 b7 b5 0c 41 d7 12 76 ea
> H.....]....A..v.
> kernel: Object ff29f54f: b1 7e 4d ed bb 74 cc c7 62 3d 2f 10 bb 74 cc c7
> .~M..t..b=/..t..
> kernel: Object 9678dfaa: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> ................
> kernel: Object 426da6d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> ................
> kernel: Object 7fab2713: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 60862a98: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 0810ad40: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 1f0aa745: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 19944bf2: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 4ce341aa: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 9607ec6d: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object a5915de7: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object d686baa6: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 1df19b0d: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 0bbe9a96: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 6f1e7700: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 824ce600: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 790d4580: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object f8a184dd: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object f65d9e18: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object b52e601b: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 82bf9d2e: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object bf8060fe: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object e90100be: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object ea74812b: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object e6403677: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object faf222d4: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object dca677d2: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 1c2391f0: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object fb8b9c6d: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object 967ee7ed: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> kkkkkkkkkkkkkkkk
> kernel: Object f597fef4: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5
> kkkkkkkkkkkkkkk.
> kernel: Redzone 13b0f2f9: bb bb bb bb
> ....
> kernel: Padding 372127fe: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a
> ZZZZZZZZZZZZZZZZ
> kernel: Padding 6d5fbace: 5a 5a 5a 5a 5a 5a 5a 5a
> ZZZZZZZZ
> kernel: CPU: 0 PID: 127 Comm: kworker/0:3 Tainted: G B
> 5.8.0-rc6-00008-g87d248347e60-dirty #1
> kernel: Hardware name: Freescale i.MX7 Dual (Device Tree)
> kernel: Workqueue: memcg_kmem_cache kmemcg_workfn
> kernel: [<8010ed20>] (unwind_backtrace) from [<8010b734>]
> (show_stack+0x10/0x14)
> kernel: [<8010b734>] (show_stack) from [<8047caf4>] (dump_stack+0x8c/0xa0)
> kernel: [<8047caf4>] (dump_stack) from [<8027351c>]
> (check_bytes_and_report+0xcc/0xe8)
> kernel: [<8027351c>] (check_bytes_and_report) from [<80274e0c>]
> (check_object+0x248/0x2ac)
> kernel: [<80274e0c>] (check_object) from [<80274edc>] (__free_slab+0x6c/0x2bc)
> kernel: [<80274edc>] (__free_slab) from [<80279a1c>]
> (__kmem_cache_shrink+0x1f4/0x248)
> kernel: [<80279a1c>] (__kmem_cache_shrink) from [<80279a7c>]
> (__kmemcg_cache_deactivate_after_rcu+0xc/0x4c)
> kernel: [<80279a7c>] (__kmemcg_cache_deactivate_after_rcu) from [<80249bb8>]
> (kmemcg_cache_deactivate_after_rcu+0xc/0x1c)
> kernel: [<80249bb8>] (kmemcg_cache_deactivate_after_rcu) from [<80249b98>]
> (kmemcg_workfn+0x24/0x38)
> kernel: [<80249b98>] (kmemcg_workfn) from [<80140000>]
> (process_one_work+0x19c/0x3e4)
> kernel: [<80140000>] (process_one_work) from [<8014028c>]
> (worker_thread+0x44/0x4dc)
> kernel: [<8014028c>] (worker_thread) from [<80146a2c>] (kthread+0x144/0x180)
> kernel: [<80146a2c>] (kthread) from [<80100148>] (ret_from_fork+0x14/0x2c)
> kernel: Exception stack(0xbb1d5fb0 to 0xbb1d5ff8)
> kernel: 5fa0: 00000000 00000000 00000000
> 00000000
> kernel: 5fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> 00000000
> kernel: 5fe0: 00000000 00000000 00000000 00000000 00000013 00000000
> kernel: FIX task_struct(119:NetworkManager-dispatcher.service): Restoring
> 0xe05e9b3f-0x9b36c418=0x6b
>
