| Message ID | 20210530002536.3193829-1-andrii@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | kbuild: skip per-CPU BTF generation for pahole v1.18-v1.21 | expand |
On Sat, May 29, 2021 at 05:25:36PM -0700, Andrii Nakryiko wrote: > Commit "mm/page_alloc: convert per-cpu list protection to local_lock" > introduced 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. > > Cc: Mel Gorman <mgorman@techsingularity.net> > Cc: Arnaldo Carvalho de Melo <acme@redhat.com> > Cc: Hao Luo <haoluo@google.com> > Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Mel Gorman <mgorman@techsingularity.net>
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index 3b342b0b0b38..66e7053aa907 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -233,6 +233,10 @@ 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 if [ "${pahole_ver}" -ge "121" ]; then extra_paholeopt="${extra_paholeopt} --btf_gen_floats" fi
Commit "mm/page_alloc: convert per-cpu list protection to local_lock" introduced 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. Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Hao Luo <haoluo@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> --- scripts/link-vmlinux.sh | 4 ++++ 1 file changed, 4 insertions(+)