On 2/5/24 11:30 AM, Andrii Nakryiko wrote:
On Sun, Feb 4, 2024 at 10:58 PM Yonghong Song <yonghong.song@xxxxxxxxx> wrote:The selftest verif_scale_strobemeta_subprogs failed with latest llvm19 compiler. For example, $ ./test_progs -n 498 ... libbpf: prog 'on_event': BPF program load failed: Permission denied libbpf: prog 'on_event': -- BEGIN PROG LOAD LOG -- combined stack size of 4 calls is 544. Too large verification time 1417195 usec stack depth 24+440+0+32Is it a `struct strobe_map_raw map` in read_map_var()? I think we should move it to a per-cpu array anyways (not saying we shouldn't fix Clang regression), in production we've done this already a while ago :)
Yes, moving 'struct strobe_map_raw map' to be a global variable does work. I just sent a kernel patch to reduce the stack requirement for jitted code, which fixed this regression. https://lore.kernel.org/bpf/20240206063010.1352503-1-yonghong.song@xxxxxxxxx/ But let us keep the code as is for now, so we could use it to capture future potential clang regressions.
processed 53561 insns (limit 1000000) max_states_per_insn 18 total_states 1457 peak_states 308 mark_read 146 -- END PROG LOAD LOG -- libbpf: prog 'on_event': failed to load: -13 libbpf: failed to load object 'strobemeta_subprogs.bpf.o' scale_test:FAIL:expect_success unexpected error: -13 (errno 13) #498 verif_scale_strobemeta_subprogs:FAIL Summary: 0/0 PASSED, 0 SKIPPED, 1 FAILED The maximum stack size exceeded 512 bytes and caused verification failure. The following llvm patch caused the above regression: https://github.com/llvm/llvm-project/pull/68882 I will do some analysis and try to find a solution to resolve this failure. Thanks, Yonghong
