Re: [rcu:dev.2020.04.05b 101/101] kprobes.c:undefined reference to `.synchronize_rcu_tasks'

["Paul E. McKenney" <paulmck@kernel.org>]

On Tue, Apr 07, 2020 at 12:06:11PM +0800, kbuild test robot wrote:
> Hi Paul,
> 
> It's probably a bug fix that unveils the link errors.

Looks like my fault, actually, but your "unveils" point is right on,
as it appears that this change exposed a bug in an earlier commit.

Will fix, and thank you for the testing!

							Thanx, Paul

> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2020.04.05b
> head:   805020c8028f6e95a8fc57132af5f896a8ad6391
> commit: 805020c8028f6e95a8fc57132af5f896a8ad6391 [101/101] squash! rcu-tasks: Add an RCU Tasks Trace to simplify protection of tracing hooks
> config: powerpc-defconfig (attached as .config)
> compiler: powerpc64-linux-gcc (GCC) 9.3.0
> reproduce:
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         git checkout 805020c8028f6e95a8fc57132af5f896a8ad6391
>         # save the attached .config to linux build tree
>         GCC_VERSION=9.3.0 make.cross ARCH=powerpc 
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kbuild test robot <lkp@intel.com>
> 
> All errors (new ones prefixed by >>):
> 
>    powerpc64-linux-ld: warning: orphan section `.gnu.hash' from `linker stubs' being placed in section `.gnu.hash'
>    powerpc64-linux-ld: kernel/kprobes.o: in function `.kprobe_optimizer':
> >> kprobes.c:(.text+0x2bc8): undefined reference to `.synchronize_rcu_tasks'
>    powerpc64-linux-ld: kernel/bpf/trampoline.o: in function `.bpf_trampoline_put':
> >> trampoline.c:(.text+0x630): undefined reference to `.synchronize_rcu_tasks'
>    powerpc64-linux-ld: kernel/bpf/trampoline.o: in function `.bpf_trampoline_update':
>    trampoline.c:(.text+0x908): undefined reference to `.synchronize_rcu_tasks'
> 
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org