Messages in this thread Patch in this message | | | From | Wanpeng Li <> | Subject | [PATCH] x86/smp: Add irq_enter/exit() in smp_reschedule_interrupt() | Date | Fri, 14 Oct 2016 09:48:53 +0800 |
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=============================== [ 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. stack backtrace: CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.8.0+ #24 Hardware name: Dell Inc. OptiPlex 7020/0F5C5X, BIOS A03 01/08/2015 ffff90285de03f58 ffffffff9d44a0c9 ffff90285ca5d100 0000000000000001 ffff90285de03f88 ffffffff9d0ebd67 ffff902845165410 000000000000080b 0000000000000000 0000000000000000 ffff90285de03fb8 ffffffff9d492b95 Call Trace: <IRQ> [<ffffffff9d44a0c9>] dump_stack+0x99/0xd0 [<ffffffff9d0ebd67>] lockdep_rcu_suspicious+0xe7/0x120 [<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 <EOI> [<ffffffff9d732634>] ? cpuidle_enter_state+0xe4/0x360 [<ffffffff9d73261f>] ? cpuidle_enter_state+0xcf/0x360 [<ffffffff9d7328e7>] cpuidle_enter+0x17/0x20 [<ffffffff9d0e1a73>] call_cpuidle+0x23/0x50 [<ffffffff9d0e1d0c>] cpu_startup_entry+0x15c/0x280 [<ffffffff9d05ce64>] start_secondary+0x154/0x180
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.
Cc: Ingo Molnar <mingo@kernel.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> --- 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 */ -- 1.9.1
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