On Jun 16, 2020, at 1:44 AM, Thomas Gleixner <tglx@linutronix.de> wrote:

kernel test robot <rong.a.chen@intel.com> writes:
FYI, we noticed the following commit (built with gcc-9):

commit: 2bbc68f8373c0631ebf137f376fbea00e8086be7 ("x86/entry: Convert Debug exception to IDTENTRY_DB")
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master

Is the head of linux.git exposing the same problem or is this an
intermittent failure, which only affects bisectability?

It sure looks deterministic:

ptrace08.c:62: BROK: Cannot find address of kernel symbol "do_debug"