kpatch-build error: can't create dynrela for section .rela.static_call_sites #1272
Description
We are seeing the following error from kpatch-build
space-info.o: changed function: __reserve_bytes
/data/users/songliubraving/kpatch/kpatch-build/create-diff-object: ERROR: space-info.o: kpatch_create_intermediate_sections: 3362: can't create dynrela for section .rela.static_call_sites (symbol __SCK__tp_func_btrfs_done_preemptive_reclaim): no bundled or section symbol
The patch to repro this error can be very simple:
diff --git i/fs/btrfs/space-info.c w/fs/btrfs/space-info.c
index e692c880deb7..ae7497b430e9 100644
--- i/fs/btrfs/space-info.c
+++ w/fs/btrfs/space-info.c
@@ -1489,6 +1489,8 @@ static int __reserve_bytes(struct btrfs_fs_info *fs_info,
int ret = 0;
bool pending_tickets;
+ if (IS_ERR(fs_info))
+ return 0;
ASSERT(orig_bytes);
ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_ALL);
After digging into this, we found this happens because missing symbol name for the .static_call_sites section. We need to access static_call_sites section for the tracepoint call trace_btrfs_done_preemptive_reclaim. The symbol name for static_call_sites is generated by the following step in scripts/Makefile.build:
cmd_modversions_c = \
if $(OBJDUMP) -h $@ | grep -q __ksymtab; then \
$(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
> $(@D)/.tmp_$(@F:.o=.ver); \
\
$(LD) $(KBUILD_LDFLAGS) -r -o $(@D)/.tmp_$(@F) $@ \
-T $(@D)/.tmp_$(@F:.o=.ver); \
mv -f $(@D)/.tmp_$(@F) $@; \
rm -f $(@D)/.tmp_$(@F:.o=.ver); \
fi
endif
As space-info.c doesn't export any symbol, space-info.o doesn't have any __ksymtab, and we skipped cmd_gensymtypes_c.
I tried a few things to fix this issue, but haven't figured out a good solution. Any suggestions on what would be the best fix here?
Thanks!