Date:   Wed, 14 Sep 2022 10:55:41 -0400
From:   Jonathan Toppins <jtoppins@...hat.com>
To:     Jay Vosburgh <jay.vosburgh@...onical.com>
Cc:     "netdev @ vger . kernel . org" <netdev@...r.kernel.org>,
        Veaceslav Falico <vfalico@...il.com>,
        Andy Gospodarek <andy@...yhouse.net>,
        Shuah Khan <shuah@...nel.org>, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org
Subject: Re: [RFC PATCH] bonding: cause oops on aarch64 architecture in
 bond_rr_gen_slave_id

On 9/14/22 10:40, Jay Vosburgh wrote:
> Jonathan Toppins <jtoppins@...hat.com> wrote:
> 
>> This bonding selftest causes the following kernel oops on aarch64 and
>> possibly ppc64le architectures. This was reproduced on net/master commit
>> 64ae13ed478428135cddc2f1113dff162d8112d4 net: core: fix flow symmetric hash
>>
>> [  329.805838] kselftest: Running tests in drivers/net/bonding
>> [  330.011028] eth0: renamed from link1_2
>> [  330.220846] eth0: renamed from link1_1
>> [  330.387755] bond0: (slave eth0): making interface the new active one
>> [  330.394165] bond0: (slave eth0): Enslaving as an active interface with an up link
>> [  330.401867] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
>> [  334.586619] bond0: (slave eth0): Releasing backup interface
>> [  334.671065] bond0: (slave eth0): Enslaving as an active interface with an up link
>> [  334.686773] Unable to handle kernel paging request at virtual address ffff2c91ac905000
>> [  334.694703] Mem abort info:
>> [  334.697486]   ESR = 0x0000000096000004
>> [  334.701234]   EC = 0x25: DABT (current EL), IL = 32 bits
>> [  334.706536]   SET = 0, FnV = 0
>> [  334.709579]   EA = 0, S1PTW = 0
>> [  334.712719]   FSC = 0x04: level 0 translation fault
>> [  334.717586] Data abort info:
>> [  334.720454]   ISV = 0, ISS = 0x00000004
>> [  334.724288]   CM = 0, WnR = 0
>> [  334.727244] swapper pgtable: 4k pages, 48-bit VAs, pgdp=000008044d662000
>> [  334.733944] [ffff2c91ac905000] pgd=0000000000000000, p4d=0000000000000000
>> [  334.740734] Internal error: Oops: 96000004 [#1] SMP
>> [  334.745602] Modules linked in: bonding tls veth rfkill sunrpc arm_spe_pmu vfat fat acpi_ipmi ipmi_ssif ixgbe igb i40e mdio ipmi_devintf ipmi_msghandler arm_cmn arm_dsu_pmu cppc_cpufreq acpi_tad fuse zram crct10dif_ce ast ghash_ce sbsa_gwdt nvme drm_vram_helper drm_ttm_helper nvme_core ttm xgene_hwmon
>> [  334.772217] CPU: 7 PID: 2214 Comm: ping Not tainted 6.0.0-rc4-00133-g64ae13ed4784 #4
>> [  334.779950] Hardware name: GIGABYTE R272-P31-00/MP32-AR1-00, BIOS F18v (SCP: 1.08.20211002) 12/01/2021
>> [  334.789244] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
>> [  334.796196] pc : bond_rr_gen_slave_id+0x40/0x124 [bonding]
>> [  334.801691] lr : bond_xmit_roundrobin_slave_get+0x38/0xdc [bonding]
> 
> 	What line in the source code is that?  Looking at the function,
> I don't really see anything that's arch specific, unless perhaps the
> rr_tx_counter assignment isn't visible for some ARM cache reason (i.e.,
> the dcache on the relevant cpu already had a populated cache line that's
> out of date, and wasn't flushed).


$ printf "%#x\n" $((0x$(nm drivers/net/bonding/bonding.ko | grep 
bond_rr_gen_slave_id | awk '{print $1}') + 0x40))
0x47d0
$ eu-addr2line -e drivers/net/bonding/bonding.ko 0x47d0
/home/jtoppins/projects/linux/./arch/arm64/include/asm/percpu.h:130:1

It appears to be a percpu arch specific issue. The cache line idea is a 
thought, not sure how to go about debugging on arm. I also have a report 
with a similar stack trace on ppc64le, but do not have a box to test on 
at this moment. I mention this as maybe someone else might see a generic 
non arch specific issue.

I could not reproduce the issue on x86_64 using a Fedora 36 kernel and 
this same test-case, I have not tested this specific upstream hash on 
x86_64. That was the plan for today.

>> [  334.807962] sp : ffff8000221733e0
>> [  334.811265] x29: ffff8000221733e0 x28: ffffdbac8572d198 x27: ffff80002217357c
>> [  334.818392] x26: 000000000000002a x25: ffffdbacb33ee000 x24: ffff07ff980fa000
>> [  334.825519] x23: ffffdbacb2e398ba x22: ffff07ff98102000 x21: ffff07ff981029c0
>> [  334.832646] x20: 0000000000000001 x19: ffff07ff981029c0 x18: 0000000000000014
>> [  334.839773] x17: 0000000000000000 x16: ffffdbacb1004364 x15: 0000aaaabe2f5a62
>> [  334.846899] x14: ffff07ff8e55d968 x13: ffff07ff8e55db30 x12: 0000000000000000
>> [  334.854026] x11: ffffdbacb21532e8 x10: 0000000000000001 x9 : ffffdbac857178ec
>> [  334.861153] x8 : ffff07ff9f6e5a28 x7 : 0000000000000000 x6 : 000000007c2b3742
>> [  334.868279] x5 : ffff2c91ac905000 x4 : ffff2c91ac905000 x3 : ffff07ff9f554400
>> [  334.875406] x2 : ffff2c91ac905000 x1 : 0000000000000001 x0 : ffff07ff981029c0
>> [  334.882532] Call trace:
>> [  334.884967]  bond_rr_gen_slave_id+0x40/0x124 [bonding]
>> [  334.890109]  bond_xmit_roundrobin_slave_get+0x38/0xdc [bonding]
>> [  334.896033]  __bond_start_xmit+0x128/0x3a0 [bonding]
>> [  334.901001]  bond_start_xmit+0x54/0xb0 [bonding]
>> [  334.905622]  dev_hard_start_xmit+0xb4/0x220
>> [  334.909798]  __dev_queue_xmit+0x1a0/0x720
>> [  334.913799]  arp_xmit+0x3c/0xbc
>> [  334.916932]  arp_send_dst+0x98/0xd0
>> [  334.920410]  arp_solicit+0xe8/0x230
>> [  334.923888]  neigh_probe+0x60/0xb0
>> [  334.927279]  __neigh_event_send+0x3b0/0x470
>> [  334.931453]  neigh_resolve_output+0x70/0x90
>> [  334.935626]  ip_finish_output2+0x158/0x514
>> [  334.939714]  __ip_finish_output+0xac/0x1a4
>> [  334.943800]  ip_finish_output+0x40/0xfc
>> [  334.947626]  ip_output+0xf8/0x1a4
>> [  334.950931]  ip_send_skb+0x5c/0x100
>> [  334.954410]  ip_push_pending_frames+0x3c/0x60
>> [  334.958758]  raw_sendmsg+0x458/0x6d0
>> [  334.962325]  inet_sendmsg+0x50/0x80
>> [  334.965805]  sock_sendmsg+0x60/0x6c
>> [  334.969286]  __sys_sendto+0xc8/0x134
>> [  334.972853]  __arm64_sys_sendto+0x34/0x4c
>> [  334.976854]  invoke_syscall+0x78/0x100
>> [  334.980594]  el0_svc_common.constprop.0+0x4c/0xf4
>> [  334.985287]  do_el0_svc+0x38/0x4c
>> [  334.988591]  el0_svc+0x34/0x10c
>> [  334.991724]  el0t_64_sync_handler+0x11c/0x150
>> [  334.996072]  el0t_64_sync+0x190/0x194
>> [  334.999726] Code: b9001062 f9403c02 d53cd044 8b040042 (b8210040)
>> [  335.005810] ---[ end trace 0000000000000000 ]---
>> [  335.010416] Kernel panic - not syncing: Oops: Fatal exception in interrupt
>> [  335.017279] SMP: stopping secondary CPUs
>> [  335.021374] Kernel Offset: 0x5baca8eb0000 from 0xffff800008000000
>> [  335.027456] PHYS_OFFSET: 0x80000000
>> [  335.030932] CPU features: 0x0000,0085c029,19805c82
>> [  335.035713] Memory Limit: none
>> [  335.038756] Rebooting in 180 seconds..
>>
>> Signed-off-by: Jonathan Toppins <jtoppins@...hat.com>
>> ---
>> .../selftests/drivers/net/bonding/Makefile    |  1 +
>> .../bonding/bond-arp-interval-causes-panic.sh | 46 +++++++++++++++++++
>> 2 files changed, 47 insertions(+)
>> create mode 100755 tools/testing/selftests/drivers/net/bonding/bond-arp-interval-causes-panic.sh
>>
>> diff --git a/tools/testing/selftests/drivers/net/bonding/Makefile b/tools/testing/selftests/drivers/net/bonding/Makefile
>> index ab6c54b12098..79bb06fd386a 100644
>> --- a/tools/testing/selftests/drivers/net/bonding/Makefile
>> +++ b/tools/testing/selftests/drivers/net/bonding/Makefile
>> @@ -2,5 +2,6 @@
>> # Makefile for net selftests
>>
>> TEST_PROGS := bond-break-lacpdu-tx.sh
>> +TEST_PROGS += bond-arp-interval-causes-panic.sh
>>
>> include ../../../lib.mk
>> diff --git a/tools/testing/selftests/drivers/net/bonding/bond-arp-interval-causes-panic.sh b/tools/testing/selftests/drivers/net/bonding/bond-arp-interval-causes-panic.sh
>> new file mode 100755
>> index 000000000000..0c3e5d486193
>> --- /dev/null
>> +++ b/tools/testing/selftests/drivers/net/bonding/bond-arp-interval-causes-panic.sh
>> @@ -0,0 +1,46 @@
>> +#!/bin/sh
>> +
>> +# cause kernel oops in bond_rr_gen_slave_id on aarch64 and ppcle
>> +# architectures
>> +DEBUG=${DEBUG:-0}
>> +
>> +set -e
>> +test ${DEBUG} -ne 0 && set -x
>> +
>> +function finish()
>> +{
>> +	ip -all netns delete
>> +	ip link del link1_1 || true
>> +}
>> +
>> +trap finish EXIT
>> +
>> +client_ip4=192.168.1.198
>> +server_ip4=192.168.1.254
>> +
>> +# setup kernel so it reboots after causing the panic
>> +echo 180 >/proc/sys/kernel/panic
>> +
>> +# build namespaces
>> +ip link add dev link1_1 type veth peer name link1_2
>> +
>> +ip netns add "server"
>> +ip link set dev link1_2 netns server up name eth0
>> +ip netns exec server ip addr add ${server_ip4}/24 dev eth0
>> +
>> +ip netns add "client"
>> +ip link set dev link1_1 netns client down name eth0
>> +ip netns exec client ip link add dev bond0 down type bond mode 1 miimon 100 all_slaves_active 1
>> +ip netns exec client ip link set dev eth0 down master bond0
>> +ip netns exec client ip link set dev bond0 up
>> +ip netns exec client ip addr add ${client_ip4}/24 dev bond0
>> +ip netns exec client ping -c 5 $server_ip4 >/dev/null
>> +
>> +ip netns exec client ip link set dev eth0 down nomaster
>> +ip netns exec client ip link set dev bond0 down
>> +ip netns exec client ip link set dev bond0 type bond mode 0 arp_interval 1000 arp_ip_target "+${server_ip4}"
>> +ip netns exec client ip link set dev eth0 down master bond0
>> +ip netns exec client ip link set dev bond0 up
>> +ip netns exec client ping -c 5 $server_ip4 >/dev/null
>> +
>> +exit 0
>> -- 
>> 2.31.1
>>
> 

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