From: Andrii Nakryiko <andrii@xxxxxxxxxx> commit a0b8200d06ad6450c179407baa5f0f52f8cfcc97 upstream. [small context changes due to missing floats support in 5.10] Commit "mm/page_alloc: convert per-cpu list protection to local_lock" will introduce a zero-sized per-CPU variable, which causes pahole to generate invalid BTF. Only pahole versions 1.18 through 1.21 are impacted, as before 1.18 pahole doesn't know anything about per-CPU variables, and 1.22 contains the proper fix for the issue. Luckily, pahole 1.18 got --skip_encoding_btf_vars option disabling BTF generation for per-CPU variables in anticipation of some unanticipated problems. So use this escape hatch to disable per-CPU var BTF info on those problematic pahole versions. Users relying on availability of per-CPU var BTFs would need to upgrade to pahole 1.22+, but everyone won't notice any regressions. Link: https://lkml.kernel.org/r/20210530002536.3193829-1-andrii@xxxxxxxxxx Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx> Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> Cc: Hao Luo <haoluo@xxxxxxxxxx> Cc: Michal Suchanek <msuchanek@xxxxxxx> Cc: Jiri Olsa <jolsa@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- scripts/link-vmlinux.sh | 5 +++++ 1 file changed, 5 insertions(+) --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -161,6 +161,11 @@ gen_btf() vmlinux_link ${1} + if [ "${pahole_ver}" -ge "118" ] && [ "${pahole_ver}" -le "121" ]; then + # pahole 1.18 through 1.21 can't handle zero-sized per-CPU vars + extra_paholeopt="${extra_paholeopt} --skip_encoding_btf_vars" + fi + info "BTF" ${2} LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${extra_paholeopt} ${1}
