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Groups > linux.kernel > #1500890

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

From tip-bot for Wanpeng Li <tipbot@zytor.com>
Newsgroups linux.kernel
Subject [tip:x86/urgent] x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt()
Date 2016-10-14 14:30 +0200
Message-ID <ss9MB-1cq-9@gated-at.bofh.it> (permalink)
References <srZNg-2Zc-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Commit-ID:  1ec6ec14a2943f6f611fc1d5fb2d4eaa85bd9d72
Gitweb:     http://git.kernel.org/tip/1ec6ec14a2943f6f611fc1d5fb2d4eaa85bd9d72
Author:     Wanpeng Li <kernellwp@gmail.com>
AuthorDate: Fri, 14 Oct 2016 09:48:53 +0800
Committer:  Thomas Gleixner <tglx@linutronix.de>
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@hotmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>
Link: http://lkml.kernel.org/r/1476409733-5133-1-git-send-email-wanpeng.li@hotmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
 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();
 	ack_APIC_irq();
 	__smp_reschedule_interrupt();
+	irq_exit();
 	/*
 	 * KVM uses this interrupt to force a cpu out of guest mode
 	 */

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Thread

[PATCH] x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt() Wanpeng Li <kernellwp@gmail.com> - 2016-10-14 03:50 +0200
  [tip:x86/urgent] x86/smp: Add irq_enter/exit() in  smp_reschedule_interrupt() tip-bot for Wanpeng Li <tipbot@zytor.com> - 2016-10-14 14:30 +0200
  Re: [PATCH] x86/smp: Add irq_enter/exit() in  smp_reschedule_interrupt() Peter Zijlstra <peterz@infradead.org> - 2016-10-16 15:40 +0200
    Re: [PATCH] x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt() Wanpeng Li <kernellwp@gmail.com> - 2016-10-17 06:30 +0200
      Re: [PATCH] x86/smp: Add irq_enter/exit() in  smp_reschedule_interrupt() Peter Zijlstra <peterz@infradead.org> - 2016-10-17 10:30 +0200
        Re: [PATCH] x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt() Wanpeng Li <kernellwp@gmail.com> - 2016-10-17 11:50 +0200
          Re: [PATCH] x86/smp: Add irq_enter/exit() in  smp_reschedule_interrupt() Paolo Bonzini <pbonzini@redhat.com> - 2016-10-17 12:20 +0200
            Re: [PATCH] x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt() Wanpeng Li <kernellwp@gmail.com> - 2016-10-17 12:30 +0200
            Re: [PATCH] x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt() Wanpeng Li <kernellwp@gmail.com> - 2016-10-18 02:10 +0200
              Re: [PATCH] x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt() Wanpeng Li <kernellwp@gmail.com> - 2016-10-19 16:20 +0200
                Re: [PATCH] x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt() Wanpeng Li <kernellwp@gmail.com> - 2016-10-19 16:40 +0200
                Re: [PATCH] x86/smp: Add irq_enter/exit() in  smp_reschedule_interrupt() Paolo Bonzini <pbonzini@redhat.com> - 2016-10-24 16:40 +0200
                Re: [PATCH] x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt() Wanpeng Li <kernellwp@gmail.com> - 2016-10-25 05:00 +0200
                Re: [PATCH] x86/smp: Add irq_enter/exit() in  smp_reschedule_interrupt() Paolo Bonzini <pbonzini@redhat.com> - 2016-10-19 18:40 +0200
        Re: [PATCH] x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt() Wanpeng Li <kernellwp@gmail.com> - 2016-10-17 14:20 +0200

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