[PATCH bpf-next 3/5] selftests/bpf: Use /tmp for temporary file in d_path

[Pu Lehui]

On 2026/9/30 0:29, Alexei Starovoitov wrote:
> On Tue, Sep 29, 2026 at 08:39 AM Pu Lehui <pulehui at huaweicloud.com> wrote:
>> The failure occurs because the rootfs created by libbpf/ci [0] does not
>> mount /dev/shm, causing temporary file creation under /dev/shm to fail.
>>
>> Let's switch to using /tmp instead to fix this issue.
> 
> This will break BPF CI.
> The test was using /tmp up to v4 and was moved to /dev/shm in v5,
> since /tmp is on 9p in BPF CI and 9p doesn't support fallocate. See
> https://lore.kernel.org/all/20251206141210.3148-1-electronlsr@gmail.com/
> vmtest's init mounts tmpfs at /dev/shm, /run and /mnt, but not at /tmp.
> So fallocate() will return EOPNOTSUPP and d_path/check_mem_access
> will fail on x86, arm64 and s390.
> 
> Mount tmpfs at /dev/shm in mkrootfs_tweak.sh like you did for /tmp in [1]
> and drop this patch.
> 
> pw-bot: cr

Hi Alexei and Ihor,

I have been make a pr for mount tmpfs at /dev/shm, pls take a look.

https://github.com/libbpf/ci/pull/239