arm64: kernel panic on 4G RAM platform

[Alexander Wilhelm]

Hello ARM64 developers,

I have a kernel panic problem on my ARM64 architecture board but I'm not sure if
it's a problem in kernel or otherwise. Maybe one could help me.

My problem is the following: I'm using the NXP TQ board with ARM64 architecture
to run OpenWRT operating system with linux kernel v5.15. The current
revision of the board (TQMLS1046A-CB.0203) has now a 4GiB RAM instead of 2GiB.
Therefore I adapted the U-Boot to use the entire memory. But now it leads to
kernel crash. Interesting is that if I only use 2GiB the problem doesn't occur.
The memory is splitted up in two different banks.

While analyzing my problem I tried to narrow down the source of my problem. But
with each new "print message" that should me help to trace the problem I get
another one. It seems like the error happens unpredictable like due to race
condition or memory access. Then I tried different RAM sizes something
in-between like 3GiB. I could boot successfully but then I got errors from
"swiotlb" if my wireless driver tried to allocate memory from my CMA pool. I
understand that the error description is vary vague but I give my best to
explain my problem. Please refer to my log of the current kernel panic state:

Starting kernel ...
[    0.000000] Booting Linux on physical CPU 0x0000000000 [0x410fd082]
[    0.000000] Linux version 5.15.158 (########@##############) (aarch64-openwrt-linux-gnu-gcc (OpenWrt GCC 12.3.0 r23630-842932a63d) 12.3.0, GNU ld (GNU Binutils) 2.37) #0 SMP Wed May 22 13:15:09 2024
[    0.000000] Machine model: #########
[    0.000000] earlycon: uart8250 at MMIO 0x00000000021c0500 (options '')
[    0.000000] printk: bootconsole [uart8250] enabled
[    0.000000] Reserved memory: created DMA memory pool at 0x00000008ff800000, size 8 MiB
[    0.000000] OF: reserved mem: initialized node qman-fqd, compatible id shared-dma-pool
[    0.000000] Reserved memory: created DMA memory pool at 0x00000008fc000000, size 32 MiB
[    0.000000] OF: reserved mem: initialized node qman-pfdr, compatible id shared-dma-pool
[    0.000000] Reserved memory: created DMA memory pool at 0x00000008fe000000, size 16 MiB
[    0.000000] OF: reserved mem: initialized node bman-fbpr, compatible id shared-dma-pool
[    0.000000] Zone ranges:
[    0.000000]   DMA      [mem 0x0000000080000000-0x00000000ffffffff]
[    0.000000]   DMA32    empty
[    0.000000]   Normal   [mem 0x0000000100000000-0x00000008ffffffff]
[    0.000000] Movable zone start for each node
[    0.000000] Early memory node ranges
[    0.000000]   node   0: [mem 0x0000000080000000-0x00000000fbdfffff]
[    0.000000]   node   0: [mem 0x0000000880000000-0x00000008fbffffff]
[    0.000000]   node   0: [mem 0x00000008fc000000-0x00000008feffffff]
[    0.000000]   node   0: [mem 0x00000008ff000000-0x00000008ff7fffff]
[    0.000000]   node   0: [mem 0x00000008ff800000-0x00000008ffffffff]
[    0.000000] Initmem setup node 0 [mem 0x0000000080000000-0x00000008ffffffff]
[    0.000000] On node 0, zone Normal: 16896 pages in unavailable ranges
[    0.000000] cma: Reserved 192 MiB at 0x00000000ee800000
[    0.000000] Failed to find device node for boot cpu
[    0.000000] /cpus/cpu at 0: missing reg property
[    0.000000] /cpus/cpu at 1: missing reg property
[    0.000000] /cpus/cpu at 2: missing reg property
[    0.000000] /cpus/cpu at 3: missing reg property
[    0.000000] Number of cores (5) exceeds configured maximum of 2 - clipping
[    0.000000] missing boot CPU MPIDR, not enabling secondaries
[    0.000000] percpu: Embedded 19 pages/cpu s37976 r8192 d31656 u77824
[    0.000000] Detected PIPT I-cache on CPU0
[    0.000000] CPU features: detected: Spectre-v2
[    0.000000] CPU features: detected: Spectre-v4
[    0.000000] CPU features: detected: Spectre-BHB
[    0.000000] Built 1 zonelists, mobility grouping on.  Total pages: 1017344
[    0.000000] Kernel command line: #######################
[    0.000000] Dentry cache hash table entries: 524288 (order: 10, 4194304 bytes, linear)
[    0.000000] Inode-cache hash table entries: 262144 (order: 9, 2097152 bytes, linear)
[    0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off
[    0.000000] software IO TLB: mapped [mem 0x00000000ea800000-0x00000000ee800000] (64MB)
[    0.000000] Memory: 3698904K/4126720K available (11776K kernel code, 968K rwdata, 3280K rodata, 576K init, 367K bss, 231208K reserved, 196608K cma-reserved)
[    0.000000] rcu: Hierarchical RCU implementation.
[    0.000000] rcu: 	RCU event tracing is enabled.
[    0.000000] rcu: 	RCU restricting CPUs from NR_CPUS=2 to nr_cpu_ids=1.
[    0.000000] 	Trampoline variant of Tasks RCU enabled.
[    0.000000] 	Rude variant of Tasks RCU enabled.
[    0.000000] 	Tracing variant of Tasks RCU enabled.
[    0.000000] rcu: RCU calculated value of scheduler-enlistment delay is 25 jiffies.
[    0.000000] rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=1
[    0.000000] NR_IRQS: 64, nr_irqs: 64, preallocated irqs: 0
[    0.000000] timer_probe: no matching timers found
[    0.000000] Kernel panic - not syncing: Unable to initialise architected timer.
[    0.000000] ---[ end Kernel panic - not syncing: Unable to initialise architected timer. ]---


Best regards
Alexander Wilhelm