Steps to reproduce:
- check that vlan_mon kernel module is inserted (lsmod | grep vlan_mon)
- create veth interface: ip link add type veth && ifconfig veth0 up
- run accel-pppd with the configuration below:
[modules] pppoe [log] log-debug=/dev/stdout level=5 [cli] tcp=127.0.0.1:2001 [pppoe] ac-name=test-accel vlan-mon=veth0,10-20 interface=re:veth0.\d+
- do nothing and wait for 10-60 seconds
- check accel-pppd status:
$ ps aux | grep accel-pppd root 11346 0.0 0.3 8696 3608 pts/0 S+ 19:08 0:00 accel-pppd -c 123.conf root 11347 0.0 0.0 0 0 pts/0 Zl+ 19:08 0:00 [accel-pppd] <defunct>
(it has zombie status)
- check dmesg:
[ 0.000000] Linux version 4.19.0-21-amd64 (debian-kernel@lists.debian.org) (gcc version 8.3.0 (Debian 8.3.0-6)) #1 SMP Debian 4.19.249-2 (2022-06-30) .... [ 1344.704891] BUG: unable to handle kernel paging request at 00003fa0c121d8e0 [ 1344.706450] PGD 0 P4D 0 [ 1344.707298] Oops: 0000 [#1] SMP NOPTI [ 1344.708188] CPU: 0 PID: 11347 Comm: accel-pppd Tainted: G OE 4.19.0-21-amd64 #1 Debian 4.19.249-2 [ 1344.710099] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 [ 1344.711770] RIP: 0010:vlan_mon_nl_cmd_add_vlan_mon+0x8f/0x2d0 [vlan_mon] [ 1344.712347] Code: 85 d5 49 89 c5 48 85 c0 0f 84 2a 02 00 00 48 c7 c7 10 80 56 c0 e8 d1 4e 36 d5 49 8b ad f0 04 00 00 48 85 ed 0f 84 4a 01 00 00 <81> 7d 003 [ 1344.713606] RSP: 0018:ffffbd8680443ad8 EFLAGS: 00000202 [ 1344.714064] RAX: 0000000000000286 RBX: ffffbd8680443b50 RCX: 0000000000008863 [ 1344.714664] RDX: 0000000000000000 RSI: 0000000000000286 RDI: 0000000000000286 [ 1344.715307] RBP: 00003fa0c121d8e0 R08: ffffffffc0567280 R09: 0000000000000000 [ 1344.715893] R10: ffff9de5bb611b80 R11: 0000000000000000 R12: 0000000000000001 [ 1344.716532] R13: ffff9de5b808d000 R14: 0000000000000003 R15: ffff9de5bb611b80 [ 1344.717191] FS: 00007f83a390acc0(0000) GS:ffff9de5bea00000(0000) knlGS:0000000000000000 [ 1344.717873] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1344.718421] CR2: 00003fa0c121d8e0 CR3: 000000003b676000 CR4: 00000000000006f0 [ 1344.719218] Call Trace: [ 1344.720516] genl_family_rcv_msg+0x1ca/0x3a0 [ 1344.720995] ? skb_queue_tail+0x1b/0x50 [ 1344.721355] ? __netlink_sendskb+0x3d/0x50 [ 1344.721721] genl_rcv_msg+0x47/0x90 [ 1344.722042] ? __kmalloc_node_track_caller+0x1dd/0x2a0 [ 1344.722514] ? genl_family_rcv_msg+0x3a0/0x3a0 [ 1344.722937] netlink_rcv_skb+0x4c/0x120 [ 1344.723327] genl_rcv+0x24/0x40 [ 1344.723601] netlink_unicast+0x181/0x210 [ 1344.723915] netlink_sendmsg+0x20b/0x3f0 [ 1344.724331] sock_sendmsg+0x36/0x40 [ 1344.724624] ___sys_sendmsg+0x295/0x2f0 [ 1344.725012] ? dev_get_by_name_rcu+0x73/0x90 [ 1344.725409] ? kmem_cache_alloc_trace+0x15e/0x1e0 [ 1344.725797] ? netlink_hash+0x29/0xa0 [ 1344.726122] ? __wake_up_common_lock+0x89/0xc0 [ 1344.726536] ? __check_object_size+0x46/0x180 [ 1344.726899] ? _copy_to_user+0x26/0x30 [ 1344.727268] ? move_addr_to_user+0xae/0xd0 [ 1344.727733] __sys_sendmsg+0x57/0xa0 [ 1344.728065] do_syscall_64+0x53/0x110 [ 1344.732564] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 1344.736084] RIP: 0033:0x7f83a3ed8467 [ 1344.739289] Code: 44 00 00 41 54 41 89 d4 55 48 89 f5 53 89 fb 48 83 ec 10 e8 3b ed ff ff 44 89 e2 48 89 ee 89 df 41 89 c0 b8 2e 00 00 00 0f 05 <48> 3d 008 [ 1344.746670] RSP: 002b:00007ffcf9ba40b0 EFLAGS: 00000293 ORIG_RAX: 000000000000002e [ 1344.750207] RAX: ffffffffffffffda RBX: 0000000000000013 RCX: 00007f83a3ed8467 [ 1344.753758] RDX: 0000000000000000 RSI: 00007ffcf9ba8110 RDI: 0000000000000013 [ 1344.757297] RBP: 00007ffcf9ba8110 R08: 0000000000000000 R09: 0000000000000000 [ 1344.760836] R10: 000055d80e2f3540 R11: 0000000000000293 R12: 0000000000000000 [ 1344.764176] R13: 00007ffcf9ba8dd0 R14: 0000000000000000 R15: 0000000000000000 [ 1344.767585] Modules linked in: veth pppoe pppox ppp_generic slhc vlan_mon(OE) nls_ascii nls_cp437 vfat fat kvm_amd ppdev ccp rng_core bochs_drm kvm ttm dry [ 1344.783379] CR2: 00003fa0c121d8e0 [ 1344.787353] ---[ end trace 278354700b21babc ]--- [ 1344.791197] RIP: 0010:vlan_mon_nl_cmd_add_vlan_mon+0x8f/0x2d0 [vlan_mon] [ 1344.795315] Code: 85 d5 49 89 c5 48 85 c0 0f 84 2a 02 00 00 48 c7 c7 10 80 56 c0 e8 d1 4e 36 d5 49 8b ad f0 04 00 00 48 85 ed 0f 84 4a 01 00 00 <81> 7d 003 [ 1344.802960] RSP: 0018:ffffbd8680443ad8 EFLAGS: 00000202 [ 1344.806489] RAX: 0000000000000286 RBX: ffffbd8680443b50 RCX: 0000000000008863 [ 1344.810492] RDX: 0000000000000000 RSI: 0000000000000286 RDI: 0000000000000286 [ 1344.814375] RBP: 00003fa0c121d8e0 R08: ffffffffc0567280 R09: 0000000000000000 [ 1344.818214] R10: ffff9de5bb611b80 R11: 0000000000000000 R12: 0000000000000001 [ 1344.821895] R13: ffff9de5b808d000 R14: 0000000000000003 R15: ffff9de5bb611b80 [ 1344.825588] FS: 00007f83a390acc0(0000) GS:ffff9de5bea00000(0000) knlGS:0000000000000000 [ 1344.829451] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1344.833111] CR2: 00003fa0c121d8e0 CR3: 000000003b676000 CR4: 00000000000006f0
This bug does not exist in Ubuntu 20.04, 22.04 , Debian 11 and Debian 12 (default generic kernels)
Looks like this bug is related to kernel, but most probably it is possible to fix in accel-pppd(vlan_mon) code. Moreover, Debian 10 EOL date is June 30th, 2024.