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

[Ihor Solodrai]

On 9/29/26 11:24 PM, Pu Lehui wrote:
> 
> On 2026/9/30 0:29, Alexei Starovoitov wrote:
>> On Tue, Sep 29, 2026 at 08:39 AM Pu Lehui <pulehui@xxxxxxxxxxxxxxx> 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@xxxxxxxxx/
>> 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


Merged, thanks.