On Wed, Dec 06, 2017 at 09:54:18PM +0100, Arnd Bergmann wrote:

On Wed, Dec 6, 2017 at 9:45 PM, kernelci.org bot bot@kernelci.org wrote:

...

stable-rc/linux-4.9.y build: 187 builds: 5 failed, 182 passed, 6 errors (v4.9.67-89-gbaa2108672eb) Full Build Summary: https://kernelci.org/build/stable-rc/branch/linux-4.9.y/kernel/v4.9.67-89-gb...

...

Build Failures Detected:

arm: gcc version 5.3.1 20160412 (Linaro GCC 5.3-2016.05) omap2plus_defconfig FAIL xcep_defconfig FAIL x86: gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.4) defconfig+CONFIG_LKDTM=y FAIL i386_defconfig FAIL x86_64_defconfig FAIL

Errors Detected:

arm: gcc version 5.3.1 20160412 (Linaro GCC 5.3-2016.05) omap2plus_defconfig 2 errors xcep_defconfig 1 error x86: gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.4) defconfig+CONFIG_LKDTM=y 1 error i386_defconfig 1 error x86_64_defconfig 1 error Errors summary: 2 kprobes.c:(.text+0x9ab7e): undefined reference to `synchronize_rcu_tasks' 1 memremap.c:(.text+0x53e78): undefined reference to `synchronize_rcu_tasks' 1 kprobes.c:(.text+0x96a50): undefined reference to `synchronize_rcu_tasks' 1 kernel/built-in.o:(.debug_addr+0x4d7c4): undefined reference to `synchronize_rcu_tasks' 1 /home/buildslave/workspace/kernel-single-defconfig-builder/defconfig/omap2plus_defconfig/label/builder/build-arm/../kernel/kprobes.c:551: undefined reference to `synchronize_rcu_tasks'

This seems to be caused by commit

ee182da1cace ("kprobes: Use synchronize_rcu_tasks() for optprobe with CONFIG_PREEMPT=y")

which is the backport of upstream commit a30b85df7d59.

I've now dropped this from the 4.9 tree, thanks.

greg k-h