Subject: [mainline][Oops][bisected 2ba3e6 ] 5.7.0 boot fails with kernel panic on powerpc

From: Abdul Haleem <[email-masked]>
Date: Wed, 03 Jun 2020 16:20:57 +0530

Greeting's

Today's mainline kernel panics when booting on my powerpc lpar

devtmpfs: initialized
clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
futex hash table entries: 8192 (order: 4, 1048576 bytes, linear)
thermal_sys: Registered thermal governor 'fair_share'
thermal_sys: Registered thermal governor 'step_wise'
BUG: Unable to handle kernel data access on read at 0xc000006000000000
Faulting instruction address: 0xc000000000393b9c
Oops: Kernel access of bad area, sig: 11 [#1]
LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
Modules linked in:
CPU: 17 PID: 1 Comm: swapper/0 Not tainted 5.7.0+ #1
NIP:  c000000000393b9c LR: c00000000039598c CTR: 0000000000000000
REGS: c000000777503660 TRAP: 0300   Not tainted  (5.7.0+)
MSR:  8000000000009033 <SF,EE,ME,IR,DR,RI,LE>  CR: 84024484  XER: 00000006
CFAR: c000000000393aa0 DAR: c000006000000000 DSISR: 40000000 IRQMASK: 0
GPR00: c00000000039598c c0000007775038f0 c00000000157fa00 6000000060000000
GPR04: ffffffffffffffff 00000000000003ff 0000000000000018 0000000000000000
GPR08: 0000000000000060 0000000000000008 0000000060000000 0000000000000100
GPR12: 0000000024024282 c000000007fa6600 c000006000000000 c008000000000000
GPR16: 800000000000018e 0000000000000000 0000000000000000 c008000000010000
GPR20: c008000000010000 c00800000000ffff 0000000000000000 c000000001533390
GPR24: c008000000010000 c00000000162d9e0 0000000000000001 0000000000000001
GPR28: c000000001600400 c00000000162d9e8 0000000000000000 c000000000000000
NIP [c000000000393b9c] map_kernel_range_noflush+0x23c/0x550
LR [c00000000039598c] __vmalloc_node_range+0x2fc/0x3f0
Call Trace:
[c0000007775039c0] [c00000000039598c] __vmalloc_node_range+0x2fc/0x3f0
[c000000777503a70] [c000000000395bb8] __vmalloc+0x58/0x70
[c000000777503ae0] [c0000000002e5f3c] bpf_prog_alloc_no_stats+0x4c/0x120
[c000000777503b20] [c0000000002e6040] bpf_prog_alloc+0x30/0xe0
[c000000777503b60] [c0000000009c4678] bpf_prog_create+0x68/0x100
[c000000777503ba0] [c000000000fbfafc] ptp_classifier_init+0x4c/0x80
[c000000777503be0] [c000000000fbeac0] sock_init+0xe0/0x100
[c000000777503c10] [c000000000011444] do_one_initcall+0x64/0x2c0
[c000000777503ce0] [c000000000f643d0] kernel_init_freeable+0x2d8/0x39c
[c000000777503db0] [c000000000011b14] kernel_init+0x2c/0x148
[c000000777503e20] [c00000000000cba8] ret_from_kernel_thread+0x5c/0x74
Instruction dump:
7ca507b4 5148463e 79ce07c6 7cc62838 7dce4378 78c61f24 79ce1564 79cef082
788ef00e 7dce3215 4182030c 38c90010 <e8ae0000> 3ad3ffff 7f663036 7d867a14
---[ end trace 598b3823c4d29f01 ]---

Kernel panic - not syncing: Fatal exception

the fault instruction 0xc000000000393b9c is in map_kernel_range_noflush
(mm/vmalloc.c:227)

System : Power 9 Power VM LPAR
kernel : mainline 5.7.0
test : boot

The patch series could have caused this regression

6c0c7d mm/ioremap: track which page-table levels were modified
2ba3e6 mm/vmalloc: track which page-table levels were modified << bad commit
d86261 mm: add functions to track page directory modifications

@Joerg, Could you please have a look?

Attaching the kernel config

-- 
Regard's

Abdul Haleem
IBM Linux Technology Centre