Subject: Re: [PATCH bpf-next 2/3] bpf: Introduce BPF_BRANCH_SNAPSHOT_F_COPY flag for bpf_get_branch_snapshot helper

From: kernel test robot <[email-masked]>
Date: Mon, 12 Jan 2026 20:22:22 +0100

Hi Leon,

kernel test robot noticed the following build errors:

[auto build test ERROR on bpf-next/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Leon-Hwang/bpf-x64-Call-perf_snapshot_branch_stack-in-trampoline/20260109-234435
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/20260109153420.32181-3-leon.hwang%40linux.dev
patch subject: [PATCH bpf-next 2/3] bpf: Introduce BPF_BRANCH_SNAPSHOT_F_COPY flag for bpf_get_branch_snapshot helper
config: x86_64-kexec (https://download.01.org/0day-ci/archive/20260112/[email-masked]/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260112/[email-masked]/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email-masked]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email-masked]/

All errors (new ones prefixed by >>):

>> ld.lld: error: undefined symbol: bpf_branch_snapshot
   >>> referenced by bpf_trace.c:1182 (kernel/trace/bpf_trace.c:1182)
   >>>               vmlinux.o:(bpf_get_branch_snapshot)
   >>> referenced by bpf_trace.c:0 (kernel/trace/bpf_trace.c:0)
   >>>               vmlinux.o:(bpf_get_branch_snapshot)

-- 
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