[tip:x86/urgent] x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt()

From: tip-bot for Wanpeng Li
Date: Fri Oct 14 2016 - 08:21:53 EST

Commit-ID: 1ec6ec14a2943f6f611fc1d5fb2d4eaa85bd9d72
Gitweb: http://git.kernel.org/tip/1ec6ec14a2943f6f611fc1d5fb2d4eaa85bd9d72
Author: Wanpeng Li <kernellwp@xxxxxxxxx>
AuthorDate: Fri, 14 Oct 2016 09:48:53 +0800
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Fri, 14 Oct 2016 14:14:20 +0200

x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt()

[ INFO: suspicious RCU usage. ]
4.8.0+ #24 Not tainted
./arch/x86/include/asm/msr-trace.h:47 suspicious rcu_dereference_check() usage!

other info that might help us debug this:

RCU used illegally from idle CPU!
rcu_scheduler_active = 1, debug_locks = 0
RCU used illegally from extended quiescent state!
no locks held by swapper/1/0.

[<ffffffff9d492b95>] do_trace_write_msr+0x135/0x140
[<ffffffff9d06f860>] native_write_msr+0x20/0x30
[<ffffffff9d065fad>] native_apic_msr_eoi_write+0x1d/0x30
[<ffffffff9d05bd1d>] smp_reschedule_interrupt+0x1d/0x30
[<ffffffff9d8daec6>] reschedule_interrupt+0x96/0xa0

Reschedule interrupt may be called in cpu idle state. This causes lockdep
check warning above.

Add irq_enter/exit() in smp_reschedule_interrupt(), irq_enter() tells the RCU
subsystems to end the extended quiescent state, so the following trace call in
ack_APIC_irq() works correctly.

Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Link: http://lkml.kernel.org/r/1476409733-5133-1-git-send-email-wanpeng.li@xxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

arch/x86/kernel/smp.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c
index 658777c..ac2ee87 100644
--- a/arch/x86/kernel/smp.c
+++ b/arch/x86/kernel/smp.c
@@ -259,8 +259,10 @@ static inline void __smp_reschedule_interrupt(void)

__visible void smp_reschedule_interrupt(struct pt_regs *regs)
+ irq_enter();
+ irq_exit();
* KVM uses this interrupt to force a cpu out of guest mode