From f64c6013a2029316ea552f99823d116ee5f5f955 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 22 May 2018 09:50:53 -0700 Subject: rcu/x86: Provide early rcu_cpu_starting() callback The x86/mtrr code does horrific things because hardware. It uses stop_machine_from_inactive_cpu(), which does a wakeup (of the stopper thread on another CPU), which uses RCU, all before the CPU is onlined. RCU complains about this, because wakeups use RCU and RCU does (rightfully) not consider offline CPUs for grace-periods. Fix this by initializing RCU way early in the MTRR case. Tested-by: Mike Galbraith Signed-off-by: Peter Zijlstra Signed-off-by: Paul E. McKenney [ paulmck: Add !SMP support, per 0day Test Robot report. ] --- arch/x86/kernel/cpu/mtrr/main.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch/x86/kernel/cpu') diff --git a/arch/x86/kernel/cpu/mtrr/main.c b/arch/x86/kernel/cpu/mtrr/main.c index 7468de429087..3ea0047beb40 100644 --- a/arch/x86/kernel/cpu/mtrr/main.c +++ b/arch/x86/kernel/cpu/mtrr/main.c @@ -46,6 +46,7 @@ #include #include #include +#include #include #include @@ -793,6 +794,9 @@ void mtrr_ap_init(void) if (!use_intel() || mtrr_aps_delayed_init) return; + + rcu_cpu_starting(smp_processor_id()); + /* * Ideally we should hold mtrr_mutex here to avoid mtrr entries * changed, but this routine will be called in cpu boot time, -- cgit v1.2.3