possible bugs on odroid, or maybe that is not meson related?

[Michał Zegan]

Hello.

On the odroid c2/meson gxbb/kernel from torwalds master, sometimes I
have random problems.
Those problems are task stalls. Once it happened when loading the usb
module, once it happened after running the find command.
A minute ago I have actually tried to switch_root manually from initrd
to real root, and there was a stall and something else.
Here it is:

swapper/2[0]: undefined instruction: pc=ffffff800853f4d4
Code: aa1a03f5 14000004 d503201f f94002b5 (b4001555)
Internal error: undefined instruction: 0 [#1] SMP
Modules linked in: squashfs loop mmc_block meson_gx_mmc pwrseq_emmc
mmc_core dwc2 udc_
core usbcore phy_meson8b_usb2 rtc_pcf8563 i2c_meson i2c_core
scpi_cpufreq arm_big_litt
le scpi_hwmon thermal_sys hwmon clk_scpi arm_scpi platform_mhu
gpio_regulator fixed nl
s_iso8859_1 nls_cp437 vfat fat btrfs raid6_pq xor crc32c_generic
crc32_generic
CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.10.0-rc1 #7
Hardware name: Hardkernel ODROID-C2 (DT)
task: ffffffc074bace00 task.stack: ffffffc074bb8000
PC is at __schedule+0x2d4/0x590
LR is at __schedule+0x2e8/0x590
pc : [<ffffff800853f4d4>] lr : [<ffffff800853f4e8>] pstate: 800001c5
sp : ffffffc074bbbef0
x29: ffffffc074bbbef0 x28: 0000000000000000
x27: 0000000000000000 x26: ffffff8008565428
x25: ffffffc074bad320 x24: ffffff800853f7b4
x23: ffffff8008897000 x22: ffffffc074bace00
x21: ffffff8008565368 x20: 0000000000000000
x19: ffffffc076fbba00 x18: 0000000000000000
x17: 00000000000045a5 x16: 0000000000000000
x15: 0000000000000000 x14: 0000000000000000
x13: 0000000000000000 x12: 0000000000000000
x11: ffffff8008565298 x10: ffffffc076fbba38
x9 : ffffffc074bbbed0 x8 : 0000000000000002
x7 : 7fffffffffffffff x6 : 0000000489f55a18
x5 : 0000000000000020 x4 : 0000000000000000
x3 : 0000000000000000 x2 : ffffff80080f73d8
x1 : ffffffc074bace00 x0 : 0000000000000000
Process swapper/2 (pid: 0, stack limit = 0xffffffc074bb8000)
Stack: (0xffffffc074bbbef0 to 0xffffffc074bbc000)
bee0:                                   ffffffc074bbbf50 ffffff800853f7b4
bf00: ffffff8008897000 ffffff8008ac9cf8 ffffff8008ac9000 ffffff800889fa48
bf20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
bf40: ffffff8008897000 ffffff8008ac9cf8 ffffffc074bbbf60 ffffff800853fadc
bf60: ffffffc074bbbf70 ffffff80080f8428 ffffffc074bbbfb0 ffffff80080f8738
bf80: 0000000000000075 0000000000000002 0000000000000000 0000000000000000
bfa0: 0000000000000000 0000000000000000 ffffffc074bbbfd0 ffffff800808d694
bfc0: 0000000000000002 0000000000000000 0000000000000000 000000000154b1a4
bfe0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
Call trace:
Exception stack(0xffffffc074bbbda0 to 0xffffffc074bbbed0)
bda0: ffffffc076fbba00 0000008000000000 ffffffc074bbbef0 ffffff800853f4d4
bdc0: 0000000000000000 ffffffc074bace00 ffffff80080f73d8 0000000000000000
bde0: 0000000000000000 0000000000000020 0000000489f55a18 7fffffffffffffff
be00: 0000000000000002 ffffffc074bbbed0 ffffffc076fbba38 ffffff8008565298
be20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
be40: 0000000000000000 00000000000045a5 0000000000000000 ffffffc076fbba00
be60: 0000000000000000 ffffff8008565368 ffffffc074bace00 ffffff8008897000
be80: ffffff800853f7b4 ffffffc074bad320 ffffff8008565428 0000000000000000
bea0: 0000000000000000 ffffffc074bbbef0 ffffff800853f4e8 ffffffc074bbbef0
bec0: ffffff800853f4d4 00000000800001c5
[<ffffff800853f4d4>] __schedule+0x2d4/0x590
[<ffffff800853f7b4>] schedule+0x24/0x80
[<ffffff800853fadc>] schedule_preempt_disabled+0xc/0x18
[<ffffff80080f8428>] do_idle+0xa8/0x1e8
[<ffffff80080f8738>] cpu_startup_entry+0x20/0x28
[<ffffff800808d694>] secondary_start_kernel+0x154/0x1b0
[<000000000154b1a4>] 0x154b1a4
Code: aa1a03f5 14000004 d503201f f94002b5 (b4001555)
INFO: rcu_sched detected stalls on CPUs/tasks:
        2-...: (1 GPs behind) idle=5a5/140000000000001/0 softirq=595/596
fqs=2100
        (detected by 1, t=6303 jiffies, g=356, c=355, q=1)
Task dump for CPU 2:
swapper/2       R  running task        0     0      1 0x00000002
Call trace:
[<ffffff80080854a4>] __switch_to+0x8c/0xb0
[<ffffff800853f4e8>] __schedule+0x2e8/0x590
[<ffffff800853f7b4>] schedule+0x24/0x80
[<ffffff800853fadc>] schedule_preempt_disabled+0xc/0x18
[<ffffff80080f8428>] do_idle+0xa8/0x1e8
[<ffffff80080f8738>] cpu_startup_entry+0x20/0x28
[<ffffff800808d694>] secondary_start_kernel+0x154/0x1b0
[<000000000154b1a4>] 0x154b1a4
INFO: rcu_sched detected stalls on CPUs/tasks:
        2-...: (1 GPs behind) idle=5a5/140000000000001/0 softirq=595/596
fqs=8398
        (detected by 1, t=25208 jiffies, g=356, c=355, q=1)
Task dump for CPU 2:
swapper/2       R  running task        0     0      1 0x00000002
Call trace:
[<ffffff80080854a4>] __switch_to+0x8c/0xb0
[<ffffff800853f4e8>] __schedule+0x2e8/0x590
[<ffffff800853f7b4>] schedule+0x24/0x80
[<ffffff800853fadc>] schedule_preempt_disabled+0xc/0x18
[<ffffff80080f8428>] do_idle+0xa8/0x1e8
[<ffffff80080f8738>] cpu_startup_entry+0x20/0x28
[<ffffff800808d694>] secondary_start_kernel+0x154/0x1b0
[<000000000154b1a4>] 0x154b1a4
INFO: rcu_sched detected stalls on CPUs/tasks:
        2-...: (1 GPs behind) idle=5a5/140000000000001/0 softirq=595/596
fqs=14696
        (detected by 1, t=44113 jiffies, g=356, c=355, q=1)
Task dump for CPU 2:
swapper/2       R  running task        0     0      1 0x00000002
Call trace:
[<ffffff80080854a4>] __switch_to+0x8c/0xb0
[<ffffff800853f4e8>] __schedule+0x2e8/0x590
[<ffffff800853f7b4>] schedule+0x24/0x80
[<ffffff800853fadc>] schedule_preempt_disabled+0xc/0x18
[<ffffff80080f8428>] do_idle+0xa8/0x1e8
[<ffffff80080f8738>] cpu_startup_entry+0x20/0x28
[<ffffff800808d694>] secondary_start_kernel+0x154/0x1b0
[<000000000154b1a4>] 0x154b1a4
INFO: rcu_sched detected stalls on CPUs/tasks:
        2-...: (1 GPs behind) idle=5a5/140000000000001/0 softirq=595/596
fqs=20994
        2-...: (1 GPs behind) idle=5a5/140000000000001/0 softirq=595/596
fqs=20994
        (detected by 1, t=63018 jiffies, g=356, c=355, q=3)
Task dump for CPU 2:
swapper/2       R  running task        0     0      1 0x00000002
Call trace:
[<ffffff80080854a4>] __switch_to+0x8c/0xb0
[<ffffff800853f4e8>] __schedule+0x2e8/0x590
[<ffffff800853f7b4>] schedule+0x24/0x80
[<ffffff800853fadc>] schedule_preempt_disabled+0xc/0x18
[<ffffff80080f8428>] do_idle+0xa8/0x1e8
[<ffffff80080f8738>] cpu_startup_entry+0x20/0x28
[<ffffff800808d694>] secondary_start_kernel+0x154/0x1b0
[<000000000154b1a4>] 0x154b1a4
INFO: rcu_sched detected stalls on CPUs/tasks:

.....
I do not know if it is related to normal stalls I get, I get them rarely
and the one before this had no stacktrace, and there was no such error
as "undefined instruction" in kernel space. But it sometimes randomly
happens.
Not sure if that is odroid problem or something in the core kernel
code/regression not related to the meson code.

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