[LTP] [PATCH net v3] tun/tap & vhost-net: make qdisc backpressure opt-in via IFF_BACKPRESSURE

Wed Jul 15 16:32:26 CEST 2026

On 7/15/26 16:01, kernel test robot wrote:
> 
> 
> Hello,
> 
> kernel test robot noticed "ltp.ioctl03.fail" on:

ioctl03.c does not know about IFF_BACKPRESSURE which is introduced here,
consequently it fails.
See [1] where it compares TUN features with known_flags.

Thanks.

[1] Link: https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/syscalls/ioctl/ioctl03.c#L82

> 
> commit: 09154ff2072e36b86ba2d92d436b7f27df153ed1 ("[PATCH net v3] tun/tap & vhost-net: make qdisc backpressure opt-in via IFF_BACKPRESSURE")
> url: https://github.com/intel-lab-lkp/linux/commits/Simon-Schippers/tun-tap-vhost-net-make-qdisc-backpressure-opt-in-via-IFF_BACKPRESSURE/20260709-181234
> base: https://git.kernel.org/cgit/linux/kernel/git/davem/net.git fabb881df322da25442f98d23f5fa371e3c78ec4
> patch link: https://lore.kernel.org/all/20260709095511.168235-1-simon.schippers@tu-dortmund.de/
> patch subject: [PATCH net v3] tun/tap & vhost-net: make qdisc backpressure opt-in via IFF_BACKPRESSURE
> 
> in testcase: ltp
> version: 
> with following parameters:
> 
> 	disk: 1HDD
> 	fs: ext4
> 	test: syscalls-03
> 
> 
> 
> config: x86_64-rhel-9.4-ltp
> compiler: gcc-14
> test machine: 4 threads 1 sockets Intel(R) Core(TM) i3-3220 CPU @ 3.30GHz (Ivy Bridge) with 8G memory
> 
> (please refer to attached dmesg/kmsg for entire log/backtrace)
> 
> 
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <oliver.sang@intel.com>
> | Closes: https://lore.kernel.org/oe-lkp/202607151550.5d829a99-lkp@intel.com
> 
> 
> ....
> 
> [1;37mgetuid03: [0m[1;32mpass[0m  (0.028s)
> [1;37mioctl03: [0m[1;31mfail[0m  (0.047s)     <-----
> [1;37mioctl05: [0m[1;32mpass[0m  (0.471s)
> 
> ....
> 
> Execution time: 3m 35s
> 
> Disconnecting from SUT: default
> 
> Target information
> ──────────────────
> Kernel:   Linux 7.2.0-rc1+ #1 SMP PREEMPT_DYNAMIC Sun Jul 12 07:25:38 CST 2026
> Cmdline:  ip=::::lkp-ivb-d04::dhcp
>           root=/dev/ram0
>           RESULT_ROOT=/result/ltp/1HDD-ext4-syscalls-03/lkp-ivb-d04/debian-13-x86_64-20250902.cgz/x86_64-rhel-9.4-ltp/gcc-14/09154ff2072e36b86ba2d92d436b7f27df153ed1/0
>           BOOT_IMAGE=/pkg/linux/x86_64-rhel-9.4-ltp/gcc-14/09154ff2072e36b86ba2d92d436b7f27df153ed1/vmlinuz-7.2.0-rc1+
>           branch=linux-devel/devel-hourly-20260709-190759
>           job=/lkp/jobs/scheduled/lkp-ivb-d04/ltp-1HDD-ext4-syscalls-03-debian-13-x86_64-20250902.cgz-09154ff2072e-20260712-19649-tc8bu6-0.yaml
>           user=lkp
>           ARCH=x86_64
>           kconfig=x86_64-rhel-9.4-ltp
>           commit=09154ff2072e36b86ba2d92d436b7f27df153ed1
>           intremap=posted_msi
>           max_uptime=7200
>           LKP_SERVER=internal-lkp-server
>           nokaslr
>           selinux=0
>           debug
>           apic=debug
>           sysrq_always_enabled
>           rcupdate.rcu_cpu_stall_timeout=100
>           net.ifnames=0
>           printk.devkmsg=on
>           panic=-1
>           softlockup_panic=1
>           nmi_watchdog=panic
>           oops=panic
>           load_ramdisk=2
>           prompt_ramdisk=0
>           drbd.minor_count=8
>           systemd.log_level=err
>           ignore_loglevel
>           console=tty0
>           earlyprintk=ttyS0,115200
>           console=ttyS0,115200
>           vga=normal
>           rw
>           keep_initrds=/osimage/pkg/debian-13-x86_64-20250902.cgz/ltp-x86_64-ed2758122-1_20260711.cgz
>           acpi_rsdp=0x000f0490
> Machine:  unknown
> Arch:     x86_64
> RAM:      6895596 kB
> Swap:     0 kB
> Distro:   debian 13
> 
> ────────────────────────
>       TEST SUMMARY
> ────────────────────────
> Suite:   syscalls-03
> Runtime: 3m 24s
> Runs:    183
> 
> Results:
>     Passed:   2144
>     Failed:   1
>     Broken:   0
>     Skipped:  222
>     Warnings: 0
> 
> [1;31mFailures:[0m
>     • ioctl03
> 
> 
> 
> The kernel config and materials to reproduce are available at:
> https://download.01.org/0day-ci/archive/20260715/202607151550.5d829a99-lkp@intel.com
> 
> 
> 