Re: [mainline][bpf] build failure: conflicting bpf_arena_* prototypes between vmlinux.h and bpf_arena_common.h

[Alexei Starovoitov]

On Mon, May 4, 2026 at 10:42 AM Venkat Rao Bagalkote
<venkat88@xxxxxxxxxxxxx> wrote:
>
> Greetings!!!
>
> I’m seeing a CLANG-BPF build failure in tools/testing/selftests/bpf
> related to conflicting prototypes of bpf_arena_* helpers between
> vmlinux.h and bpf_arena_common.h, on mainline kernel.
>
>
> Error log:
>
>    In file included from progs/arena_strsearch.c:12:
>    In file included from
> tools/testing/selftests/bpf/bpf_arena_strsearch.h:4:
>    tools/testing/selftests/bpf/bpf_arena_common.h:47:15:
>      error: conflicting types for 'bpf_arena_alloc_pages'
>        void __arena* bpf_arena_alloc_pages(void *map,
>                                            void __arena *addr,
>                                            __u32 page_cnt,
>                                            __u32 node_id,
>                                            __u64 flags);
>
>    tools/testing/selftests/bpf/tools/include/vmlinux.h:135295:14:
>      note: previous declaration is here
>        extern void *bpf_arena_alloc_pages(void *p__map,
>                                           void *addr__ign,
>                                           u32 page_cnt,
>                                           int node_id,
>                                           u64 flags) __weak __ksym;
>
>    tools/testing/selftests/bpf/bpf_arena_common.h:49:5:
>      error: conflicting types for 'bpf_arena_reserve_pages'
>        int bpf_arena_reserve_pages(void *map,
>                                    void __arena *addr,
>                                    __u32 page_cnt) __ksym __weak;
>
>    tools/testing/selftests/bpf/tools/include/vmlinux.h:135297:12:
>      note: previous declaration is here
>        extern int bpf_arena_reserve_pages(void *p__map,
>                                           void *ptr__ign,
>                                           u32 page_cnt) __weak __ksym;
>
>    tools/testing/selftests/bpf/bpf_arena_common.h:50:6:
>      error: conflicting types for 'bpf_arena_free_pages'
>        void bpf_arena_free_pages(void *map,
>                                  void __arena *ptr,
>                                  __u32 page_cnt) __ksym __weak;
>
>    tools/testing/selftests/bpf/tools/include/vmlinux.h:135296:13:
>      note: previous declaration is here
>        extern void bpf_arena_free_pages(void *p__map,
>                                         void *ptr__ign,
>                                         u32 page_cnt) __weak __ksym;
>
> Tool chain Versions:
>
> gcc (GCC) 14.2.0
> # clang --version
> clang version 23.0.0git (https://github.com/llvm/llvm-project.git
> bd6bfba3e50343c112a04b639394ab85be17c29b)
>
> # llc --version
> LLVM (http://llvm.org/):
>    LLVM version 23.0.0git
>    Optimized build.
>    Default target: powerpc64le-unknown-linux-gnu
>    Host CPU: (unknown)
>
>    Registered Targets:
>      bpf     - BPF (host endian)
>      bpfeb   - BPF (big endian)
>      bpfel   - BPF (little endian)
>      ppc32   - PowerPC 32
>      ppc32le - PowerPC 32 LE
>      ppc64   - PowerPC 64
>      ppc64le - PowerPC 64 LE
>
> # objcopy --version | head -1
> GNU objcopy version 2.35.2-67.el9_7.1
> # ld --version | head -1
> GNU ld version 2.35.2-67.el9_7.1
>
>
> If you happen to fix this, please add below tag.
>
>
> Reported-by: Venkat Rao Bagalkote <venkat88@xxxxxxxxxxxxx>

The issue is in your setup.
It was brought up a couple times in the past.
Please search archives.