kernel/bpf/Makefile builds arena.o only for CONFIG_MMU && CONFIG_64BIT, but special_kfunc_list references bpf_arena_alloc_pages() and bpf_arena_free_pages() unconditionally, so on 32-bit and !MMU kernels resolve_btfids can't resolve them: WARN: resolve_btfids: unresolved symbol bpf_arena_free_pages WARN: resolve_btfids: unresolved symbol bpf_arena_alloc_pages Since commit 201a454df948 ("resolve_btfids: Fix the --fatal_warnings exit status") these warnings fail the build with CONFIG_WERROR=y, which breaks i386 builds with CONFIG_DEBUG_INFO_BTF=y: Failed to generate BTF for vmlinux Try to disable CONFIG_DEBUG_INFO_BTF Only reference them under the condition arena.o is built with, and use BTF_ID_UNUSED otherwise to keep the list in sync with enum special_kfunc_type. An unresolved ID is zero, like BTF_ID_UNUSED, so the contents of the list don't change. Fixes: b8467290edab ("bpf: arena: make arena kfuncs any context safe") Assisted-by: LLM Signed-off-by: Sasha Levin --- kernel/bpf/verifier.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 22f095b9dca2d..12229713a4528 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -13639,8 +13639,13 @@ BTF_ID(func, bpf_task_work_schedule_signal) BTF_ID(func, bpf_task_work_schedule_resume) BTF_ID(func, bpf_call_rcu) BTF_ID(func, bpf_call_rcu_tasks_trace) +#if defined(CONFIG_MMU) && defined(CONFIG_64BIT) BTF_ID(func, bpf_arena_alloc_pages) BTF_ID(func, bpf_arena_free_pages) +#else +BTF_ID_UNUSED +BTF_ID_UNUSED +#endif #ifdef CONFIG_BPF_EVENTS BTF_ID(func, bpf_session_is_return) #else -- 2.53.0