Re: [Regression Bug] Re: [PATCH net v3 2/2] ppp: fix race conditions in ppp_fill_forward_path

Hi Eric,

On Fri, Aug 29, 2025 at 9:05 PM cam enih [off-list ref] wrote:

Hi all,
Having upgraded from 6.12.43 to 6.12.44, my kernel crashed at early boot. The root cause is most likely related to the commit 94731cc551e29511d85aa8dec61a6c071b1f2430 (Fixes: f6efc675c9dd ("net: ppp: resolve forwarding path for bridge pppoe devices")). Please confirm, thanks.

Does this happen only if you set up a PPPoE connection?

-Eric

Aug 29 20:36:16 localhost kernel: NET: Registered PF_PPPOX protocol family
Aug 29 20:36:17 localhost systemd-networkd[266]: Failed to parse hostname, ignoring: Invalid argument
Aug 29 20:36:17 localhost systemd-networkd[266]: br0: DHCPv4 server: DISCOVER (0xebeec00c)
Aug 29 20:36:17 localhost kernel: BUG: kernel NULL pointer dereference, address: 0000000000000058
Aug 29 20:36:17 localhost kernel: #PF: supervisor read access in kernel mode
Aug 29 20:36:17 localhost kernel: #PF: error_code(0x0000) - not-present page
Aug 29 20:36:17 localhost kernel: PGD 0 P4D 0
Aug 29 20:36:17 localhost kernel: Oops: Oops: 0000 [#1] PREEMPT_RT SMP
Aug 29 20:36:17 localhost kernel: CPU: 1 UID: 981 PID: 266 Comm: systemd-network Not tainted 6.12.44-xanmod1-1-lts #1

Looks like it's a downstream fork:
https://gitlab.com/xanmod/linux/-/releases/6.12.44-xanmod1
Have you reported to them too?

Aug 29 20:36:17 localhost kernel: Hardware name: Default string Default string/Default string, BIOS 5.19 03/30/2021
Aug 29 20:36:17 localhost kernel: RIP: 0010:0xffffffffb32b2f6c
Aug 29 20:36:17 localhost kernel: Code: 85 8e 01 00 00 48 8b 44 24 08 48 8b 40 30 65 48 03 05 48 26 d6 4c e9 f0 fd ff ff e8 5e 9c c1 ff e9 ca fc ff ff 49 8b 44 24 18 <48> 8b 40 58 48 3d 00 e3 65 b3 0f 84 0f 01 00 00 48 89 c2 48 8d 78
Aug 29 20:36:17 localhost kernel: RSP: 0018:ffff9bd080c778d8 EFLAGS: 00010246
Aug 29 20:36:17 localhost kernel: RAX: 0000000000000000 RBX: ffff9bd080c77a00 RCX: 0000000000000001
Aug 29 20:36:17 localhost kernel: RDX: 0000000000000000 RSI: 000000000002a424 RDI: ffffffffb38b6040
Aug 29 20:36:17 localhost kernel: RBP: ffff999345ad1000 R08: 0000000000000003 R09: 0000000000000000
Aug 29 20:36:17 localhost kernel: R10: ffff999342eb7900 R11: 0000000000000000 R12: ffff9bd080c77948
Aug 29 20:36:17 localhost kernel: R13: 0000000000000008 R14: 0000000000000000 R15: 0000000090000000
Aug 29 20:36:17 localhost kernel: FS: 00007fc0bab148c0(0000) GS:ffff9994b7d00000(0000) knlGS:0000000000000000
Aug 29 20:36:17 localhost kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Aug 29 20:36:17 localhost kernel: CR2: 0000000000000058 CR3: 000000010b438006 CR4: 0000000000b70ef0
Aug 29 20:36:17 localhost kernel: Call Trace:
Aug 29 20:36:17 localhost kernel: <TASK>
Aug 29 20:36:17 localhost kernel: ? 0xffffffffb321d725
Aug 29 20:36:17 localhost kernel: 0xffffffffb32b4197
Aug 29 20:36:17 localhost kernel: 0xffffffffb32f5d6c
Aug 29 20:36:17 localhost kernel: ? 0xffffffffb32b8c40
Aug 29 20:36:17 localhost kernel: ? 0xffffffffb3212da5
Aug 29 20:36:17 localhost kernel: 0xffffffffb3212da5
Aug 29 20:36:17 localhost kernel: 0xffffffffb32131ea
Aug 29 20:36:17 localhost kernel: 0xffffffffb32152ea
Aug 29 20:36:17 localhost kernel: 0xffffffffb3364479
Aug 29 20:36:17 localhost kernel: ? 0xffffffffb3364485
Aug 29 20:36:17 localhost kernel: ? 0xffffffffb3215617
Aug 29 20:36:17 localhost kernel: ? 0xffffffffb2f2cd31
Aug 29 20:36:17 localhost kernel: ? 0xffffffffb33684f7
Aug 29 20:36:17 localhost kernel: 0xffffffffb34000b0

Do they have a debug kernel image with KALLSYMS, so I won't be looking
at some random hex?

Thanks
- Qingfang