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

[Alexei Starovoitov]

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