[Cake] cake infinite loop(?) with hfsc on one-armed router

Pete Heist pete at heistp.net
Sat Jan 5 06:06:44 EST 2019


Quick update to the trace because I had to apply the patch manually and missed one line to remove (qdisc_tree_reduce_backlog...), just so it doesn’t through off the addresses for you, but it still does the same thing:

root at apu1a:~/src/sch_cake# [  697.089814] BUG: unable to handle kernel NULL pointer dereference at 00000008
[  697.097009] IP: [<f9f39834>] adjust_parent_qlen+0x37/0xf08 [sch_cake]
[  697.103491] *pde = 00000000 
[  697.106405] Oops: 0000 [#1] SMP 
[  697.109697] Modules linked in: em_meta cls_basic sch_hfsc sch_cake(O) xt_ACCOUNT(O) ipt_REJECT xt_recent iptable_mangle iptable_nat nfn
[  697.160768] CPU: 1 PID: 0 Comm: swapper/1 Tainted: G           O  3.16.7-ckt9-voyage #1
[  697.168776] Hardware name: PC Engines APU/APU, BIOS 4.0 09/08/2014
[  697.174957] task: f5c811d0 ti: f5c86000 task.ti: f5c86000
[  697.180366] EIP: 0060:[<f9f39834>] EFLAGS: 00210206 CPU: 1
[  697.185862] EIP is at adjust_parent_qlen+0x37/0xf08 [sch_cake]
[  697.191701] EAX: f5cdd000 EBX: ffffffe8 ECX: 00000000 EDX: 00000003
[  697.197977] ESI: 00010000 EDI: f2f00000 EBP: f5c99cf0 ESP: f5c99ce8
[  697.204250]  DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
[  697.209648] CR0: 8005003b CR2: 00000008 CR3: 305c6000 CR4: 00000790
[  697.215913] Stack:
[  697.217932]  000000ba ef8f0000 f5c99d84 f9f3a12a e0b706f9 0209090a 000011be 000017a8
[  697.225879]  00000000 00000004 000000b9 f2f02e80 00200246 000000ba ef8f0100 c131996d
[  697.233828]  93ceb5ff 0000009f f5486e80 f5486e80 f5c99dbc f5c99d54 0209090a 0209480a
[  697.241776] Call Trace:
[  697.244239]  [<f9f3a12a>] adjust_parent_qlen+0x92d/0xf08 [sch_cake]
[  697.250524]  [<c131996d>] ? _raw_spin_unlock_bh+0x13/0x15
[  697.255936]  [<c129f91c>] ? tc_classify_compat+0x2f/0x5f
[  697.261254]  [<c12a091e>] ? tc_classify+0x1a/0x8b
[  697.265967]  [<f9f45a8f>] 0xf9f45a8e
[  697.269564]  [<c128b628>] __dev_queue_xmit+0x210/0x35f
[  697.274715]  [<c12af74e>] ? ip_fragment+0x79f/0x79f
[  697.279601]  [<c128b78b>] dev_queue_xmit+0xa/0xc
[  697.284231]  [<c12916f9>] neigh_resolve_output+0x12f/0x145
[  697.289727]  [<c12afaa0>] ip_finish_output+0x352/0x73d
[  697.294872]  [<c12b0e19>] ip_output+0x73/0xaf
[  697.299240]  [<c12ad986>] ip_forward_finish+0x66/0x6b
[  697.304301]  [<c12adc3b>] ip_forward+0x2b0/0x36d
[  697.308930]  [<c12ac467>] ip_rcv_finish+0x267/0x29a
[  697.313817]  [<c12aca4c>] ip_rcv+0x2b4/0x338
[  697.318103]  [<c12895dd>] __netif_receive_skb_core+0x467/0x4b6
[  697.323944]  [<c1289674>] __netif_receive_skb+0x48/0x59
[  697.329176]  [<c1289cb9>] netif_receive_skb_internal+0x59/0x85
[  697.335017]  [<c1289d6c>] napi_gro_complete+0x87/0x8c
[  697.340080]  [<c128a020>] napi_gro_flush+0x3e/0x53
[  697.344880]  [<c128a04c>] napi_complete+0x17/0x27
[  697.349594]  [<f81161a3>] 0xf81161a2
[  697.353186]  [<c128a0b2>] net_rx_action+0x56/0x10e
[  697.357986]  [<c102d689>] __do_softirq+0x91/0x175
[  697.362701]  [<c102d5f8>] ? __hrtimer_tasklet_trampoline+0x1a/0x1a
[  697.368886]  [<c10033c3>] do_softirq_own_stack+0x1d/0x23
[  697.374203]  <IRQ> 
[  697.376136]  [<c102d8a9>] irq_exit+0x34/0x75
[  697.380646]  [<c1002f30>] do_IRQ+0x92/0xa6
[  697.384755]  [<c131a4ec>] common_interrupt+0x2c/0x40
[  697.389733]  [<c126add1>] ? cpuidle_enter_state+0x37/0x96
[  697.395137]  [<c126aee8>] cpuidle_enter+0xf/0x12
[  697.399768]  [<c1051e54>] cpu_startup_entry+0x135/0x1e1
[  697.405002]  [<c101d553>] start_secondary+0x1a6/0x1ab
[  697.410056] Code: 70 24 85 f6 74 5e 66 31 f6 81 fe 00 00 ff ff 74 53 8b 40 34 8b 00 f6 40 08 01 75 05 39 70 20 74 16 8b 58 18 83 eb 183
[  697.430491] EIP: [<f9f39834>] adjust_parent_qlen+0x37/0xf08 [sch_cake] SS:ESP 0068:f5c99ce8
[  697.438891] CR2: 0000000000000008
[  697.442220] ---[ end trace 4fdb119875d1f11d ]---
[  697.446847] Kernel panic - not syncing: Fatal exception in interrupt
[  697.453281] Kernel Offset: 0x0 from 0xc1000000 (relocation range: 0xc0000000-0xf7ffdfff)
[  697.461426] Rebooting in 30 seconds..


> On Jan 5, 2019, at 11:59 AM, Pete Heist <pete at heistp.net> wrote:
> 
> 
>> On Jan 5, 2019, at 11:06 AM, Toke Høiland-Jørgensen <toke at toke.dk> wrote:
>> 
>> Hmm, try this version for 3.16 - probably doesn't work on later kernels.
>> I'll look into a proper backport once you've confirmed that it works :)
> 
> Thanks! Quick reminder, I’ve only seen this happen with hfsc, not when cake is a leaf below htb, for whatever reason, but that aside...
> 
> After the patch I was able to do an iperf3 upload through the one-armed router (receive on default VLAN and send on tagged VLAN), but when I ran iperf3 in reverse mode (receive on tagged VLAN and send on default VLAN), this happened right away (also see compile warnings below):
> 
> 
> root at apu1a:~# [  341.268556] BUG: unable to handle kernel NULL pointer dereference at 00000008
> [  341.275801] IP: [<fa0e8834>] adjust_parent_qlen+0x37/0xf1a [sch_cake]
> [  341.282290] *pde = 00000000 
> [  341.285203] Oops: 0000 [#1] SMP 
> [  341.288496] Modules linked in: em_meta cls_basic sch_hfsc sch_cake(O) xt_ACCOUNT(O) ipt_REJECT xt_recent iptable_mangle iptable_nat nfi
> [  341.339568] CPU: 1 PID: 0 Comm: swapper/1 Tainted: G           O  3.16.7-ckt9-voyage #1
> [  341.347576] Hardware name: PC Engines APU/APU, BIOS 4.0 09/08/2014
> [  341.353765] task: f5c811d0 ti: f5c86000 task.ti: f5c86000
> [  341.359173] EIP: 0060:[<fa0e8834>] EFLAGS: 00210206 CPU: 1
> [  341.364669] EIP is at adjust_parent_qlen+0x37/0xf1a [sch_cake]
> [  341.370508] EAX: f5d65000 EBX: ffffffe8 ECX: 00000000 EDX: 00000003
> [  341.376774] ESI: 00010000 EDI: f2900000 EBP: f5c99cf0 ESP: f5c99ce8
> [  341.383041]  DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
> [  341.388447] CR0: 8005003b CR2: 00000008 CR3: 35cde000 CR4: 00000790
> [  341.394713] Stack:
> [  341.396734]  000001e1 f56f0000 f5c99d84 fa0e913c e0b706f9 0209090a f2907840 000017a8
> [  341.404678]  00000000 00000004 000001e0 000001e1 f56f0100 f2a90000 000017a8 c131996d
> [  341.412626]  ca4edbd8 0000004d f54fca00 f54fca00 f5c99dbc f5c99d54 0209090a 0209480a
> [  341.420573] Call Trace:
> [  341.423037]  [<fa0e913c>] adjust_parent_qlen+0x93f/0xf1a [sch_cake]
> [  341.429322]  [<c131996d>] ? _raw_spin_unlock_bh+0x13/0x15
> [  341.434734]  [<c129f91c>] ? tc_classify_compat+0x2f/0x5f
> [  341.440054]  [<c12a091e>] ? tc_classify+0x1a/0x8b
> [  341.444767]  [<fa0f4a8f>] 0xfa0f4a8e
> [  341.448361]  [<c128b628>] __dev_queue_xmit+0x210/0x35f
> [  341.453504]  [<c12af74e>] ? ip_fragment+0x79f/0x79f
> [  341.458392]  [<c128b78b>] dev_queue_xmit+0xa/0xc
> [  341.463023]  [<c12916f9>] neigh_resolve_output+0x12f/0x145
> [  341.468517]  [<c12afaa0>] ip_finish_output+0x352/0x73d
> [  341.473664]  [<c12b0e19>] ip_output+0x73/0xaf
> [  341.478033]  [<c12ad986>] ip_forward_finish+0x66/0x6b
> [  341.483091]  [<c12adc3b>] ip_forward+0x2b0/0x36d
> [  341.487720]  [<c12ac467>] ip_rcv_finish+0x267/0x29a
> [  341.492607]  [<c12aca4c>] ip_rcv+0x2b4/0x338
> [  341.496894]  [<c12895dd>] __netif_receive_skb_core+0x467/0x4b6
> [  341.502741]  [<c1289674>] __netif_receive_skb+0x48/0x59
> [  341.507975]  [<c1289cb9>] netif_receive_skb_internal+0x59/0x85
> [  341.513818]  [<c1289d6c>] napi_gro_complete+0x87/0x8c
> [  341.518878]  [<c128a020>] napi_gro_flush+0x3e/0x53
> [  341.523680]  [<c128a04c>] napi_complete+0x17/0x27
> [  341.528394]  [<f80361a3>] 0xf80361a2
> [  341.531985]  [<c128a0b2>] net_rx_action+0x56/0x10e
> [  341.536785]  [<c102d689>] __do_softirq+0x91/0x175
> [  341.541501]  [<c102d5f8>] ? __hrtimer_tasklet_trampoline+0x1a/0x1a
> [  341.547685]  [<c10033c3>] do_softirq_own_stack+0x1d/0x23
> [  341.553002]  <IRQ> 
> [  341.554933]  [<c102d8a9>] irq_exit+0x34/0x75
> [  341.559445]  [<c1002f30>] do_IRQ+0x92/0xa6
> [  341.563554]  [<c131a4ec>] common_interrupt+0x2c/0x40
> [  341.568531]  [<c126add1>] ? cpuidle_enter_state+0x37/0x96
> [  341.573936]  [<c126aee8>] cpuidle_enter+0xf/0x12
> [  341.578567]  [<c1051e54>] cpu_startup_entry+0x135/0x1e1
> [  341.583802]  [<c101d553>] start_secondary+0x1a6/0x1ab
> [  341.588856] Code: 70 24 85 f6 74 5e 66 31 f6 81 fe 00 00 ff ff 74 53 8b 40 34 8b 00 f6 40 08 01 75 05 39 70 20 74 16 8b 58 18 83 eb 18e
> [  341.609292] EIP: [<fa0e8834>] adjust_parent_qlen+0x37/0xf1a [sch_cake] SS:ESP 0068:f5c99ce8
> [  341.617689] CR2: 0000000000000008
> [  341.621012] ---[ end trace db8ecd998020cc49 ]---
> [  341.625639] Kernel panic - not syncing: Fatal exception in interrupt
> [  341.632073] Kernel Offset: 0x0 from 0xc1000000 (relocation range: 0xc0000000-0xf7ffdfff)
> [  341.640215] Rebooting in 30 seconds..
> 
> 
> 
> Probably less critically, some compile warnings:
> 
> root at apu1a:~/src/sch_cake# make clean
> make[1]: Entering directory '/usr/src/linux-headers-3.16.7-ckt9-voyage'
>  CLEAN   /root/src/sch_cake/.tmp_versions
>  CLEAN   /root/src/sch_cake/Module.symvers
> make[1]: Leaving directory '/usr/src/linux-headers-3.16.7-ckt9-voyage'
> root at apu1a:~/src/sch_cake# make
> make[1]: Entering directory '/usr/src/linux-headers-3.16.7-ckt9-voyage'
>  CC [M]  /root/src/sch_cake/sch_cake.o
> /root/src/sch_cake/sch_cake.c: In function ‘adjust_parent_qlen’:
> /root/src/sch_cake/sch_cake.c:1753:31: warning: passing argument 1 of ‘qdisc_match_from_root’ from incompatible pointer type
>   sch = qdisc_match_from_root(qdisc_dev(sch), TC_H_MAJ(parentid));
>                               ^
> /root/src/sch_cake/sch_cake.c:1727:22: note: expected ‘struct Qdisc *’ but argument is of type ‘struct net_device *’
> static struct Qdisc *qdisc_match_from_root(struct Qdisc *root, u32 handle)
>                      ^
>  Building modules, stage 2.
>  MODPOST 1 modules
>  CC      /root/src/sch_cake/sch_cake.mod.o
>  LD [M]  /root/src/sch_cake/sch_cake.ko
> make[1]: Leaving directory '/usr/src/linux-headers-3.16.7-ckt9-voyage'
> 



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