On 5/6/26 7:31 PM, Paul Menzel wrote:
Dear Linux folks,
After a long while, on the 8335-GCA POWER8 (raw) 0x4d0200
opal:skiboot-5.4.8-5787ad3 PowerNV, I built Linux from Linus’ master
branch and rebooted via kexec.
```
[ 0.000000] Linux version 7.1.0-rc2+
([email protected]) (gcc
(Ubuntu 11.2.0-7ubuntu2) 11.2.0, GNU ld (GNU Binutils for Ubuntu)
2.37) #3 SMP PREEMPT Wed May 6 08:50:58 CEST 2026
[…]
[ 17.901992] Kernel attempted to read user page (0) - exploit
attempt? (uid: 0)
[ 17.902011] BUG: Kernel NULL pointer dereference on read at 0x00000000
[ 17.902018] Faulting instruction address: 0xc0000000000e7138
[ 17.902027] Oops: Kernel access of bad area, sig: 11 [#1]
[ 17.902034] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA PowerNV
[ 17.902045] Modules linked in: powernv_rng(+) bnx2x ofpart
ibmpowernv bfq mdio cmdlinepart powernv_flash ipmi_powernv
ipmi_devintf mtd ipmi_msghandler at24(+) vmx_crypto opal_prd
sch_fq_codel nfsd parport_pc ppdev auth_rpcgss nfs_acl lp lockd grace
parport sunrpc autofs4 btrfs xor libblake2b raid6_pq ast
drm_shmem_helper drm_client_lib i2c_algo_bit drm_kms_helper drm ahci
drm_panel_orientation_quirks libahci
[ 17.902185] CPU: 147 UID: 0 PID: 2626 Comm: hwrng Not tainted
7.1.0-rc2+ #3 PREEMPTLAZY
[ 17.902197] Hardware name: 8335-GCA POWER8 (raw) 0x4d0200
opal:skiboot-5.4.8-5787ad3 PowerNV
[ 17.902204] NIP: c0000000000e7138 LR: c00800001ec8013c CTR:
c0000000000e70fc
[ 17.902212] REGS: c000000092913c50 TRAP: 0300 Not tainted
(7.1.0-rc2+)
[ 17.902222] MSR: 900000000280b033
<SF,HV,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 44420220 XER: 20000000
[ 17.902269] CFAR: c00800001ec8026c DAR: 0000000000000000 DSISR:
40000000 IRQMASK: 0
GPR00: c00800001ec8013c c000000092913ef0
c000000001c18100 c00000002222d900
GPR04: c00000002222d900 0000000000000080
0000000000000001 0000000000000000
GPR08: 0000000000000000 c000000002212000
c0000000951e1780 c00800001ec80258
GPR12: c0000000000e70fc c00000ffff6fd700
c0000000001d11c0 c00000001b99b9c0
GPR16: 0000000000000000 0000000000000000
0000000000000000 0000000000000000
GPR20: 0000000000000000 0000000000000000
0000000000000000 0000000000000000
GPR24: 0000000000000000 c000000002fe6a58
0000000000000000 0000000000000000
GPR28: c000000002fe6a20 0000000000000010
000000000000000f c00000002222d900
[ 17.902406] NIP [c0000000000e7138] pnv_get_random_long+0x3c/0x114
[ 17.902426] LR [c00800001ec8013c] powernv_rng_read+0x78/0xc4
[powernv_rng]
[ 17.902444] Call Trace:
[ 17.902448] [c000000092913ef0] [c000000092913f30]
0xc000000092913f30 (unreliable)
[ 17.902463] [c000000092913f30] [c000000000decd58]
hwrng_fillfn+0xd4/0x3dc
[ 17.902484] [c000000092913f90] [c0000000001d1328] kthread+0x170/0x1a4
[ 17.902498] [c000000092913fe0] [c00000000000d030]
start_kernel_thread+0x14/0x18
[ 17.902513] Code: 60000000 7d2000a6 71290010 418200bc e94d0908
812a0000 39290001 912a0000 e90d0030 3d220060 39299f00 7d08482a
<e9280000> 7c0004ac e8e90000 0c070000
[ 17.902569] ---[ end trace 0000000000000000 ]---
[ 18.008801] pstore: backend (nvram) writing error (-1)
[ 18.015458] note: hwrng[2626] exited with irqs disabled
[ 18.015483] note: hwrng[2626] exited with preempt_count 1
```
Please find the output of `dmesg` attached.
This is from my yesterday's boot test log in my P8, did not see this fail.
root@ltcppm1:~# uname -a
Linux ltcppm1.ltc.tadn.ibm.com 7.1.0-rc2-00021-gf583bd5f64d4 #1 SMP
PREEMPT Wed May 6 00:55:45 EDT 2026 ppc64le GNU/Linux
root@ltcppm1:~# dmesg
[ 0.000000] [ T0] random: crng init done
[ 0.000000] [ T0] hash-mmu: Page sizes from device-tree:
[ 0.000000] [ T0] hash-mmu: base_shift=12: shift=12,
sllp=0x0000, avpnm=0x00000000, tlbiel=1, penc=0
[ 0.000000] [ T0] hash-mmu: base_shift=12: shift=16,
sllp=0x0000, avpnm=0x00000000, tlbiel=1, penc=7
[ 0.000000] [ T0] hash-mmu: base_shift=12: shift=24,
sllp=0x0000, avpnm=0x00000000, tlbiel=1, penc=56
[ 0.000000] [ T0] hash-mmu: base_shift=16: shift=16,
sllp=0x0110, avpnm=0x00000000, tlbiel=1, penc=1
[ 0.000000] [ T0] hash-mmu: base_shift=16: shift=24,
sllp=0x0110, avpnm=0x00000000, tlbiel=1, penc=8
[ 0.000000] [ T0] hash-mmu: base_shift=24: shift=24,
sllp=0x0100, avpnm=0x00000001, tlbiel=0, penc=0
[ 0.000000] [ T0] hash-mmu: base_shift=34: shift=34,
sllp=0x0120, avpnm=0x000007ff, tlbiel=0, penc=3
[ 0.000000] [ T0] Enabling pkeys with max key count 32
[ 0.000000] [ T0] Activating Kernel Userspace Access Prevention
[ 0.000000] [ T0] Activating Kernel Userspace Execution Prevention
[ 0.000000] [ T0] hash-mmu: Page orders: linear mapping = 24,
virtual = 16, io = 16, vmemmap = 24
[ 0.000000] [ T0] hash-mmu: Using 1TB segments
[ 0.000000] [ T0] hash-mmu: Initializing hash mmu with SLB
[ 0.000000] [ T0] Linux version 7.1.0-rc2-00021-gf583bd5f64d4
([email protected]) (gcc (GCC) 16.1.1 20260501 (Red Hat
16.1.1-1), GNU ld version 2.46-1.fc44) #1 SMP PREEMPT Wed May 6
00:55:45 EDT 2026
[ 0.000000] [ T0] OF: reserved mem:
0x0000000039c00000..0x000000003b6801ff (27136 KiB) map non-reusable
ibm,firmware-allocs-memory@39c00000
[ 0.000000] [ T0] OF: reserved mem:
0x0000000800000000..0x0000000800e801ff (14848 KiB) map non-reusable
ibm,firmware-allocs-memory@800000000
[ 0.000000] [ T0] OF: reserved mem:
0x0000001000000000..0x0000001000dc01ff (14080 KiB) map non-reusable
ibm,firmware-allocs-memory@1000000000
[ 0.000000] [ T0] OF: reserved mem:
0x0000001800000000..0x0000001800e801ff (14848 KiB) map non-reusable
ibm,firmware-allocs-memory@1800000000
[ 0.000000] [ T0] OF: reserved mem:
0x0000000030000000..0x00000000302fffff (3072 KiB) map non-reusable
ibm,firmware-code@30000000
[ 0.000000] [ T0] OF: reserved mem:
0x0000000031000000..0x0000000031bfffff (12288 KiB) map non-reusable
ibm,firmware-data@31000000
[ 0.000000] [ T0] OF: reserved mem:
0x0000000030300000..0x0000000030ffffff (13312 KiB) map non-reusable
ibm,firmware-heap@30300000
[ 0.000000] [ T0] OF: reserved mem:
0x0000000031c00000..0x0000000033fdffff (36736 KiB) map non-reusable
ibm,firmware-stacks@31c00000
[ 0.000000] [ T0] OF: reserved mem:
0x0000001ffd510000..0x0000001ffd69ffff (1600 KiB) map non-reusable
ibm,hbrt-code-image@1ffd510000
[ 0.000000] [ T0] OF: reserved mem:
0x0000001ffd6a0000..0x0000001ffd6fffff (384 KiB) map non-reusable
ibm,hbrt-target-image@1ffd6a0000
[ 0.000000] [ T0] OF: reserved mem:
0x0000001ffd700000..0x0000001ffd7fffff (1024 KiB) map non-reusable
ibm,hbrt-vpd-image@1ffd700000
[ 0.000000] [ T0] OF: reserved mem:
0x0000001ffda00000..0x0000001ffdafffff (1024 KiB) map non-reusable
ibm,slw-image@1ffda00000
[ 0.000000] [ T0] OF: reserved mem:
0x0000001ffde00000..0x0000001ffdefffff (1024 KiB) map non-reusable
ibm,slw-image@1ffde00000
[ 0.000000] [ T0] OF: reserved mem:
0x0000001ffe200000..0x0000001ffe2fffff (1024 KiB) map non-reusable
ibm,slw-image@1ffe200000
[ 0.000000] [ T0] OF: reserved mem:
0x0000001ffe600000..0x0000001ffe6fffff (1024 KiB) map non-reusable
ibm,slw-image@1ffe600000
[ 0.000000] [ T0] Found initrd at
0xc000000006a40000:0xc00000000815ae9e
[ 0.000000] [ T0] Hardware name: 8247-22L POWER8E (raw) 0x4b0201
opal:skiboot-v5.4.12 PowerNV
[ 0.000000] [ T0] printk: legacy bootconsole [udbg0] enabled
[ 0.000000] [ T0] CPU maps initialized for 8 threads per core
[ 0.000000] [ T0] (thread shift is 3)But I my opal version 5.4.12.
Thanks for reporting the issue, will have an look at it.
[ 0.000000] [ T0] Allocated 4608 bytes for 160 pacas
[ 0.000000] [ T0]
-----------------------------------------------------
.......
[ 37.407674] [ T900] audit: type=1130 audit(1778043621.931:10):
pid=1 uid=0 auid=4294967295 ses=4294967295 msg='unit=lvm2-monitor
comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=?
terminal=? res=success'
[ 37.413015] [ T900] audit: type=1130 audit(1778043621.937:11):
pid=1 uid=0 auid=4294967295 ses=4294967295 msg='unit=systemd-sysctl
comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=?
terminal=? res=success'
[ 38.448156] [ T2286] powernv_rng: Registered powernv hwrng.
[ 38.575227] [ T2264] tg3 0005:09:00.1 enP5p9s0f1: renamed from eth1
[ 38.582176] [ T2223] tg3 0005:09:00.2 enP5p9s0f2: renamed from eth2
........
////cpuinfo output
processor : 159
cpu : POWER8E (raw), altivec supported
clock : 2061.000000MHz
revision : 2.1 (pvr 004b 0201)
timebase : 512000000
platform : PowerNV
model : 8247-22L
machine : PowerNV 8247-22L
firmware : OPAL
MMU : Hash
But my system opal version 5.4.12.
Thanks for reporting the issue, will have an look at it.
Maddy
Kind regards,
Paul
