Re: selftests: net/mptcp: mptcp_connect.sh - Internal error: Oops: qdisc_block_add_dev (net/sched/sch_api.c:1191)

[Matthieu Baerts]

Hi Naresh,

On 02/01/2024 10:48, Naresh Kamboju wrote:
> Following kernel oops noticed on qemu-arm64 while running
> selftests: net/mptcp: mptcp_connect.sh test cases on Linux next-20240102

Thank you for having cc MPTCP list for this failure with an MPTCP selftest.

> Reported-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>
> 
> Test log:
> ---
> # selftests: net/mptcp: mptcp_connect.sh
> # INFO: set ns3-6593b550-fBKovo dev ns3eth2: ethtool -K  gso off
> # INFO: set ns4-6593b550-fBKovo dev ns4eth3: ethtool -K  gro off
> # Created /tmp/tmp.vFrp4xubYR (size 219663 /tmp/tmp.vFrp4xubYR)
> containing data sent by client
> # Created /tmp/tmp.FrEUtOwsBN (size 5630063 /tmp/tmp.FrEUtOwsBN)
> containing data sent by server
> # New MPTCP socket can be blocked via sysctl [ OK ]
> # INFO: validating network environment with pings
> <6>[   32.891365] netem: version 1.3
> <1>[   32.901072] Unable to handle kernel NULL pointer dereference at
> virtual address 0000000000000000
> <1>[   32.901926] Mem abort info:
> <1>[   32.903342]   ESR = 0x0000000086000004
> <1>[   32.903768]   EC = 0x21: IABT (current EL), IL = 32 bits
> <1>[   32.904589]   SET = 0, FnV = 0
> <1>[   32.905415]   EA = 0, S1PTW = 0
> <1>[   32.905914]   FSC = 0x04: level 0 translation fault
> <1>[   32.909254] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000103097000
> <1>[   32.909914] [0000000000000000] pgd=0000000000000000, p4d=0000000000000000
> <0>[   32.913724] Internal error: Oops: 0000000086000004 [#1] PREEMPT SMP
> <4>[   32.914739] Modules linked in: sch_netem crct10dif_ce sm3_ce sm3
> sha3_ce sha512_ce sha512_arm64 fuse drm backlight dm_mod ip_tables
> x_tables
> <4>[   32.916764] CPU: 0 PID: 438 Comm: tc Not tainted
> 6.7.0-rc8-next-20240102 #1
> <4>[   32.917555] Hardware name: linux,dummy-virt (DT)
> <4>[   32.918608] pstate: 63400809 (nZCv daif +PAN -UAO +TCO +DIT
> -SSBS BTYPE=-c)
> <4>[   32.919392] pc : 0x0
> <4>[ 32.920396] lr : qdisc_block_add_dev (net/sched/sch_api.c:1191)

It doesn't look like to be an issue with MPTCP, but with TC (QDisc).

It seems like the issue has already been reported. There is even a patch
that has been proposed by Victor (but it looks like a new version is
expected):

https://lore.kernel.org/netdev/20231231172320.245375-1-victor@xxxxxxxxxxxx/

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.