From a7c734140aa36413944eef0f8c660e0e2256357d Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 12 Jul 2016 21:59:23 +0200 Subject: [PATCH] cpu/hotplug: Keep enough storage space if SMP=n to avoid array out of bounds scribble Xiaolong Ye reported lock debug warnings triggered by the following commit: 8de4a0066106 ("perf/x86: Convert the core to the hotplug state machine") The bug is the following: the cpuhp_bp_states[] array is cut short when CONFIG_SMP=n, but the dynamically registered callbacks are stored nevertheless and happily scribble outside of the array bounds... We need to store them in case that the state is unregistered so we can invoke the teardown function. That's independent of CONFIG_SMP. Make sure the array is large enough. Reported-by: kernel test robot Signed-off-by: Thomas Gleixner Cc: Adam Borowski Cc: Alexander Shishkin Cc: Anna-Maria Gleixner Cc: Arnaldo Carvalho de Melo Cc: Arnaldo Carvalho de Melo Cc: Borislav Petkov Cc: Jiri Olsa Cc: Kan Liang Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Sebastian Andrzej Siewior Cc: Stephane Eranian Cc: Vince Weaver Cc: lkp@01.org Cc: stable@vger.kernel.org Cc: tipbuild@zytor.com Fixes: cff7d378d3fd "cpu/hotplug: Convert to a state machine for the control processor" Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1607122144560.4083@nanos Signed-off-by: Ingo Molnar --- kernel/cpu.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/cpu.c b/kernel/cpu.c index d948e44c471e..7b61887f7ccd 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -1201,6 +1201,8 @@ static struct cpuhp_step cpuhp_bp_states[] = { .teardown = takedown_cpu, .cant_stop = true, }, +#else + [CPUHP_BRINGUP_CPU] = { }, #endif };