Subject: Re: 4.1.0, kernel panic, pppoe_release

From: Dan Williams <[email-masked]>
Date: Fri, 17 Jul 2015 10:36:40 -0500

On Fri, 2015-07-17 at 12:24 +0300, Denys Fedoryshchenko wrote:
> As i suspect, this kernel panic caused by recent changes to pppoe.
> This problem appearing in accel-pppd (server), on loaded servers (2k 
> users and more).
> Most probably related to changed "pppoe: Use workqueue to die properly 
> when a PADT is received"
> I will try to reverse this and related patches.

While I didn't write the patch, I'm the one that started the process
that got it submitted...  Could you review the patch quickly too to see
if you can spot anything amiss with it, so that it could get fixed up?
The original patch does fix a real problem so ideally we don't have to
revert the whole thing upstream.

Dan

> On 2015-07-14 13:57, Denys Fedoryshchenko wrote:
> > Here is panic message from netconsole. Please let me know if any
> > additional information required.
> > 
> > Jul 14 13:49:16 10.0.252.10 [76078.867822] BUG: unable to handle kernel
> > Jul 14 13:49:16 10.0.252.10 NULL pointer dereference
> > Jul 14 13:49:16 10.0.252.10 at 00000000000003f0
> > Jul 14 13:49:16 10.0.252.10 [76078.868280] IP:
> > Jul 14 13:49:16 10.0.252.10 [<ffffffffa011e12a>]
> > pppoe_release+0x56/0x142 [pppoe]
> > Jul 14 13:49:16 10.0.252.10 [76078.868541] PGD 336e4a067
> > Jul 14 13:49:16 10.0.252.10 PUD 333f17067
> > Jul 14 13:49:16 10.0.252.10 PMD 0
> > Jul 14 13:49:16 10.0.252.10
> > Jul 14 13:49:16 10.0.252.10 [76078.868918] Oops: 0000 [#1]
> > Jul 14 13:49:16 10.0.252.10 SMP
> > Jul 14 13:49:16 10.0.252.10
> > Jul 14 13:49:16 10.0.252.10 [76078.869226] Modules linked in:
> > Jul 14 13:49:16 10.0.252.10 netconsole
> > Jul 14 13:49:16 10.0.252.10 configfs
> > Jul 14 13:49:16 10.0.252.10 coretemp
> > Jul 14 13:49:16 10.0.252.10 sch_fq
> > Jul 14 13:49:16 10.0.252.10 cls_fw
> > Jul 14 13:49:16 10.0.252.10 act_police
> > Jul 14 13:49:16 10.0.252.10 cls_u32
> > Jul 14 13:49:16 10.0.252.10 sch_ingress
> > Jul 14 13:49:16 10.0.252.10 sch_sfq
> > Jul 14 13:49:16 10.0.252.10 sch_htb
> > Jul 14 13:49:16 10.0.252.10 pppoe
> > Jul 14 13:49:16 10.0.252.10 pppox
> > Jul 14 13:49:16 10.0.252.10 ppp_generic
> > Jul 14 13:49:16 10.0.252.10 slhc
> > Jul 14 13:49:16 10.0.252.10 nf_nat_pptp
> > Jul 14 13:49:16 10.0.252.10 nf_nat_proto_gre
> > Jul 14 13:49:16 10.0.252.10 nf_conntrack_pptp
> > Jul 14 13:49:16 10.0.252.10 nf_conntrack_proto_gre
> > Jul 14 13:49:16 10.0.252.10 tun
> > Jul 14 13:49:16 10.0.252.10 xt_REDIRECT
> > Jul 14 13:49:16 10.0.252.10 nf_nat_redirect
> > Jul 14 13:49:16 10.0.252.10 xt_set
> > Jul 14 13:49:16 10.0.252.10 xt_TCPMSS
> > Jul 14 13:49:16 10.0.252.10 ipt_REJECT
> > Jul 14 13:49:16 10.0.252.10 nf_reject_ipv4
> > Jul 14 13:49:16 10.0.252.10 ts_bm
> > Jul 14 13:49:16 10.0.252.10 xt_string
> > Jul 14 13:49:16 10.0.252.10 xt_connmark
> > Jul 14 13:49:16 10.0.252.10 xt_DSCP
> > Jul 14 13:49:16 10.0.252.10 xt_mark
> > Jul 14 13:49:16 10.0.252.10 xt_tcpudp
> > Jul 14 13:49:16 10.0.252.10 iptable_mangle
> > Jul 14 13:49:16 10.0.252.10 iptable_filter
> > Jul 14 13:49:16 10.0.252.10 iptable_nat
> > Jul 14 13:49:16 10.0.252.10 nf_conntrack_ipv4
> > Jul 14 13:49:16 10.0.252.10 nf_defrag_ipv4
> > Jul 14 13:49:16 10.0.252.10 nf_nat_ipv4
> > Jul 14 13:49:16 10.0.252.10 nf_nat
> > Jul 14 13:49:16 10.0.252.10 nf_conntrack
> > Jul 14 13:49:16 10.0.252.10 ip_tables
> > Jul 14 13:49:16 10.0.252.10 x_tables
> > Jul 14 13:49:16 10.0.252.10 ip_set_hash_ip
> > Jul 14 13:49:16 10.0.252.10 ip_set
> > Jul 14 13:49:16 10.0.252.10 nfnetlink
> > Jul 14 13:49:16 10.0.252.10 8021q
> > Jul 14 13:49:16 10.0.252.10 garp
> > Jul 14 13:49:16 10.0.252.10 mrp
> > Jul 14 13:49:16 10.0.252.10 stp
> > Jul 14 13:49:16 10.0.252.10 llc
> > Jul 14 13:49:16 10.0.252.10 [last unloaded: netconsole]
> > Jul 14 13:49:16 10.0.252.10
> > Jul 14 13:49:16 10.0.252.10 [76078.873195] CPU: 3 PID: 2940 Comm:
> > accel-pppd Not tainted 4.1.0-build-0074 #7
> > Jul 14 13:49:16 10.0.252.10 [76078.873396] Hardware name: HP ProLiant
> > DL320e Gen8 v2, BIOS P80 04/02/2015
> > Jul 14 13:49:16 10.0.252.10 [76078.873598] task: ffff8800b1886ba0 ti:
> > ffff8800b09f4000 task.ti: ffff8800b09f4000
> > Jul 14 13:49:16 10.0.252.10 [76078.873929] RIP: 
> > 0010:[<ffffffffa011e12a>]
> > Jul 14 13:49:16 10.0.252.10 [<ffffffffa011e12a>]
> > pppoe_release+0x56/0x142 [pppoe]
> > Jul 14 13:49:16 10.0.252.10 [76078.874317] RSP: 0018:ffff8800b09f7e28
> > EFLAGS: 00010202
> > Jul 14 13:49:16 10.0.252.10 [76078.874512] RAX: 0000000000000000 RBX:
> > ffff88032a214400 RCX: 0000000000000000
> > Jul 14 13:49:16 10.0.252.10 [76078.874709] RDX: 000000000000000d RSI:
> > 00000000fffffe01 RDI: ffffffff8180d6da
> > Jul 14 13:49:16 10.0.252.10 [76078.874906] RBP: ffff8800b09f7e68 R08:
> > 0000000000000000 R09: 0000000000000000
> > Jul 14 13:49:16 10.0.252.10 [76078.875102] R10: ffff88031ef6a110 R11:
> > 0000000000000293 R12: ffff88030f8d8fc0
> > Jul 14 13:49:16 10.0.252.10 [76078.875299] R13: ffff88030f8d8ff0 R14:
> > ffff88033115ee40 R15: ffff8803394e4920
> > Jul 14 13:49:16 10.0.252.10 [76078.875499] FS:  00007f79b602c700(0000)
> > GS:ffff880347460000(0000) knlGS:0000000000000000
> > Jul 14 13:49:16 10.0.252.10 [76078.875837] CS:  0010 DS: 0000 ES: 0000
> > CR0: 0000000080050033
> > Jul 14 13:49:16 10.0.252.10 [76078.876036] CR2: 00000000000003f0 CR3:
> > 0000000335425000 CR4: 00000000001407e0
> > Jul 14 13:49:16 10.0.252.10 [76078.876239] Stack:
> > Jul 14 13:49:16 10.0.252.10 [76078.876434]  ffff88033ac45c80
> > Jul 14 13:49:16 10.0.252.10 0000000000000000
> > Jul 14 13:49:16 10.0.252.10 0000000100000000
> > Jul 14 13:49:16 10.0.252.10 ffff88030f8d8fc0
> > Jul 14 13:49:16 10.0.252.10
> > Jul 14 13:49:16 10.0.252.10 [76078.877001]  ffffffffa0120260
> > Jul 14 13:49:16 10.0.252.10 ffff88030f8d8ff0
> > Jul 14 13:49:16 10.0.252.10 ffff88033115ee40
> > Jul 14 13:49:16 10.0.252.10 ffff8803394e4920
> > Jul 14 13:49:16 10.0.252.10
> > Jul 14 13:49:16 10.0.252.10 [76078.877564]  ffff8800b09f7e88
> > Jul 14 13:49:16 10.0.252.10 ffffffff81809e2e
> > Jul 14 13:49:16 10.0.252.10 ffff88031ef6a100
> > Jul 14 13:49:16 10.0.252.10 0000000000000008
> > Jul 14 13:49:16 10.0.252.10
> > Jul 14 13:49:16 10.0.252.10 [76078.878128] Call Trace:
> > Jul 14 13:49:16 10.0.252.10 [76078.878327]  [<ffffffff81809e2e>]
> > sock_release+0x1a/0x78
> > Jul 14 13:49:16 10.0.252.10 [76078.878528]  [<ffffffff81809e99>]
> > sock_close+0xd/0x11
> > Jul 14 13:49:16 10.0.252.10 [76078.878728]  [<ffffffff81150395>]
> > __fput+0xdf/0x193
> > Jul 14 13:49:16 10.0.252.10 [76078.878926]  [<ffffffff81150477>]
> > ____fput+0x9/0xb
> > Jul 14 13:49:16 10.0.252.10 [76078.879124]  [<ffffffff810cfa95>]
> > task_work_run+0x85/0x9c
> > Jul 14 13:49:16 10.0.252.10 [76078.879326]  [<ffffffff81002979>]
> > do_notify_resume+0x40/0x4e
> > Jul 14 13:49:16 10.0.252.10 [76078.879527]  [<ffffffff818a4a0a>]
> > int_signal+0x12/0x17
> > Jul 14 13:49:16 10.0.252.10 [76078.879726] Code:
> > Jul 14 13:49:16 10.0.252.10 48
> > Jul 14 13:49:16 10.0.252.10 8b
> > Jul 14 13:49:16 10.0.252.10 83
> > Jul 14 13:49:16 10.0.252.10 e0
> > Jul 14 13:49:16 10.0.252.10 00
> > Jul 14 13:49:16 10.0.252.10 00
> > Jul 14 13:49:16 10.0.252.10 00
> > Jul 14 13:49:16 10.0.252.10 a8
> > Jul 14 13:49:16 10.0.252.10 01
> > Jul 14 13:49:16 10.0.252.10 74
> > Jul 14 13:49:16 10.0.252.10 12
> > Jul 14 13:49:16 10.0.252.10 48
> > Jul 14 13:49:16 10.0.252.10 89
> > Jul 14 13:49:16 10.0.252.10 df
> > Jul 14 13:49:16 10.0.252.10 e8
> > Jul 14 13:49:16 10.0.252.10 87
> > Jul 14 13:49:16 10.0.252.10 f9
> > Jul 14 13:49:16 10.0.252.10 6e
> > Jul 14 13:49:16 10.0.252.10 e1
> > Jul 14 13:49:16 10.0.252.10 b8
> > Jul 14 13:49:16 10.0.252.10 f7
> > Jul 14 13:49:16 10.0.252.10 ff
> > Jul 14 13:49:16 10.0.252.10 ff
> > Jul 14 13:49:16 10.0.252.10 ff
> > Jul 14 13:49:16 10.0.252.10 e9
> > Jul 14 13:49:16 10.0.252.10 eb
> > Jul 14 13:49:16 10.0.252.10 00
> > Jul 14 13:49:16 10.0.252.10 00
> > Jul 14 13:49:16 10.0.252.10 00
> > Jul 14 13:49:16 10.0.252.10 8a
> > Jul 14 13:49:16 10.0.252.10 43
> > Jul 14 13:49:16 10.0.252.10 12
> > Jul 14 13:49:16 10.0.252.10 a8
> > Jul 14 13:49:16 10.0.252.10 0b
> > Jul 14 13:49:16 10.0.252.10 74
> > Jul 14 13:49:16 10.0.252.10 1c
> > Jul 14 13:49:16 10.0.252.10 48
> > Jul 14 13:49:16 10.0.252.10 8b
> > Jul 14 13:49:16 10.0.252.10 83
> > Jul 14 13:49:16 10.0.252.10 b0
> > Jul 14 13:49:16 10.0.252.10 02
> > Jul 14 13:49:16 10.0.252.10 00
> > Jul 14 13:49:16 10.0.252.10 00
> > Jul 14 13:49:16 10.0.252.10
> > Jul 14 13:49:16 10.0.252.10 8b
> > Jul 14 13:49:16 10.0.252.10 80
> > Jul 14 13:49:16 10.0.252.10 f0
> > Jul 14 13:49:16 10.0.252.10 03
> > Jul 14 13:49:16 10.0.252.10 00
> > Jul 14 13:49:16 10.0.252.10 00
> > Jul 14 13:49:16 10.0.252.10 65
> > Jul 14 13:49:16 10.0.252.10 ff
> > Jul 14 13:49:16 10.0.252.10 08
> > Jul 14 13:49:16 10.0.252.10 48
> > Jul 14 13:49:16 10.0.252.10 c7
> > Jul 14 13:49:16 10.0.252.10 83
> > Jul 14 13:49:16 10.0.252.10 b0
> > Jul 14 13:49:16 10.0.252.10 02
> > Jul 14 13:49:16 10.0.252.10 00
> > Jul 14 13:49:16 10.0.252.10 00
> > Jul 14 13:49:16 10.0.252.10 00
> > Jul 14 13:49:16 10.0.252.10 00
> > Jul 14 13:49:16 10.0.252.10 00
> > Jul 14 13:49:16 10.0.252.10 00
> > Jul 14 13:49:16 10.0.252.10
> > Jul 14 13:49:16 10.0.252.10 [76078.883913] RIP
> > Jul 14 13:49:16 10.0.252.10 [<ffffffffa011e12a>]
> > pppoe_release+0x56/0x142 [pppoe]
> > Jul 14 13:49:16 10.0.252.10 [76078.884171]  RSP <ffff8800b09f7e28>
> > Jul 14 13:49:16 10.0.252.10 [76078.884368] CR2: 00000000000003f0
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.867822] BUG: unable to
> > handle kernel NULL pointer dereference at 00000000000003f0
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.868280] IP:
> > [<ffffffffa011e12a>] pppoe_release+0x56/0x142 [pppoe]
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.868541] PGD 336e4a067 PUD
> > 333f17067 PMD 0
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.868918] Oops: 0000 [#1] SMP
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.869226] Modules linked in:
> > netconsole configfs coretemp sch_fq cls_fw act_police cls_u32
> > sch_ingress sch_sfq sch_htb pppoe pppox ppp_generic slhc nf_nat_pptp
> > nf_nat_proto_gre nf_conntrack_pptp nf_conntrack_proto_gre tun
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.873195] CPU: 3 PID: 2940
> > Comm: accel-pppd Not tainted 4.1.0-build-0074 #7
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.873396] Hardware name: HP
> > ProLiant DL320e Gen8 v2, BIOS P80 04/02/2015
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.873598] task:
> > ffff8800b1886ba0 ti: ffff8800b09f4000 task.ti: ffff8800b09f4000
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.873929] RIP:
> > 0010:[<ffffffffa011e12a>]  [<ffffffffa011e12a>]
> > pppoe_release+0x56/0x142 [pppoe]
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.874317] RSP:
> > 0018:ffff8800b09f7e28  EFLAGS: 00010202
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.874512] RAX:
> > 0000000000000000 RBX: ffff88032a214400 RCX: 0000000000000000
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.874709] RDX:
> > 000000000000000d RSI: 00000000fffffe01 RDI: ffffffff8180d6da
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.874906] RBP:
> > ffff8800b09f7e68 R08: 0000000000000000 R09: 0000000000000000
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.875102] R10:
> > ffff88031ef6a110 R11: 0000000000000293 R12: ffff88030f8d8fc0
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.875299] R13:
> > ffff88030f8d8ff0 R14: ffff88033115ee40 R15: ffff8803394e4920
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.875499] FS:
> > 00007f79b602c700(0000) GS:ffff880347460000(0000)
> > knlGS:0000000000000000
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.875837] CS:  0010 DS: 0000
> > ES: 0000 CR0: 0000000080050033
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.876036] CR2:
> > 00000000000003f0 CR3: 0000000335425000 CR4: 00000000001407e0
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.876239] Stack:
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.876434]  ffff88033ac45c80
> > 0000000000000000 0000000100000000 ffff88030f8d8fc0
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.877001]  ffffffffa0120260
> > ffff88030f8d8ff0 ffff88033115ee40 ffff8803394e4920
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.877564]  ffff8800b09f7e88
> > ffffffff81809e2e ffff88031ef6a100 0000000000000008
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.878128] Call Trace:
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.878327]
> > [<ffffffff81809e2e>] sock_release+0x1a/0x78
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.878528]
> > [<ffffffff81809e99>] sock_close+0xd/0x11
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.878728]
> > [<ffffffff81150395>] __fput+0xdf/0x193
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.878926]
> > [<ffffffff81150477>] ____fput+0x9/0xb
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.879124]
> > [<ffffffff810cfa95>] task_work_run+0x85/0x9c
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.879326]
> > [<ffffffff81002979>] do_notify_resume+0x40/0x4e
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.879527]
> > [<ffffffff818a4a0a>] int_signal+0x12/0x17
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.879726] Code: 48 8b 83 e0
> > 00 00 00 a8 01 74 12 48 89 df e8 87 f9 6e e1 b8 f7 ff ff ff e9 eb 00
> > 00 00 8a 43 12 a8 0b 74 1c 48 8b 83 b0 02 00 00 <48> 8b 80 f0 03 00 00
> > 65 ff 08 48 c7 83 b0 02 00 00 00 00 00 00
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.883913] RIP
> > [<ffffffffa011e12a>] pppoe_release+0x56/0x142 [pppoe]
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.884171]  RSP 
> > <ffff8800b09f7e28>
> > Jul 14 10:49:16 10.0.252.10 kernel: [76078.884368] CR2: 
> > 00000000000003f0
> > Jul 14 13:49:16 10.0.252.10 [76078.884972] ---[ end trace 
> > 7fa41f8b4758f1fa ]---
> > Jul 14 10:49:16 10.0.252.10 accel-pppd: pppoe: discard PADR packet
> > (incorrect AC-Cookie)
> > Jul 14 10:49:17 10.0.252.10 kernel: [76078.884972] ---[ end trace
> > 7fa41f8b4758f1fa ]---
> > Jul 14 13:49:17 10.0.252.10 [76078.936849] Kernel panic - not syncing:
> > Fatal exception
> > Jul 14 13:49:17 10.0.252.10 [76078.937054] Kernel Offset: disabled
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