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Date: Fri, 28 Jun 2013 14:16:03 -0400 From: Steven Rostedt <rostedt@...dmis.org> To: Seiji Aguchi <seiji.aguchi@....com> Cc: linux-kernel@...r.kernel.org, x86@...nel.org, hpa@...or.com, mingo@...e.hu, tglx@...utronix.de Subject: Re: [PATCH -tip] x86,trace: Add irq_enter/exit() in smp_trace_reschedule_interrupt() On Fri, 2013-06-28 at 14:02 -0400, Seiji Aguchi wrote: > Reschedule vector tracepoints may be called in cpu idle state. > This causes lockdep check warning below. > > The tracepoint requires rcu but for accuracy it also > requires irq_enter() (tracepoints record the irq context), thus, the > tracepoint interrupt handler should be calling irq_enter() and not > rcu_irq_enter() (irq_enter() calls rcu_irq_enter()). > > So, add irq_enter/exit() to smp_trace_reschedule_interrupt() > with common pre/post processing functions, smp_entering_irq() > and exiting_irq() (exiting_irq() calls just irq_exit() > in arch/x86/include/asm/apic.h), > because these can be shared among reschedule, call_function, > and call_function_single vectors. > > [ 50.720557] Testing event reschedule_exit: > [ 50.721349] > [ 50.721502] =============================== > [ 50.721835] [ INFO: suspicious RCU usage. ] > [ 50.722169] 3.10.0-rc6-00004-gcf910e8 #190 Not tainted > [ 50.722582] ------------------------------- > [ 50.722915] /c/kernel-tests/src/linux/arch/x86/include/asm/trace/irq_vectors.h:50 suspicious rcu_dereference_check() usage! > [ 50.723770] > [ 50.723770] other info that might help us debug this: > [ 50.723770] > [ 50.724385] > [ 50.724385] RCU used illegally from idle CPU! > [ 50.724385] rcu_scheduler_active = 1, debug_locks = 0 > [ 50.725232] RCU used illegally from extended quiescent state! > [ 50.725690] no locks held by swapper/0/0. > [ 50.726010] > [ 50.726010] stack backtrace: > [ 50.726359] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.10.0-rc6-00004-gcf910e8 #190 > [ 50.726965] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 > > [ 50.727417] 00000001 00000001 79c53f04 798bd9f9 79c53f2c 79077a70 79b412c6 79b41fd1 > [ 50.728159] 00000001 00000000 79c5ef8c 87147c58 00000000 79c55800 79c53f38 79010b65 > [ 50.728849] 79c52000 79c53f7c 798c720e 79c52000 79c5ef8c 00000004 00000000 79c55800 > [ 50.729532] Call Trace: > [ 50.729730] [<798bd9f9>] dump_stack+0x16/0x18 > [ 50.730072] [<79077a70>] lockdep_rcu_suspicious+0xf2/0xfa > [ 50.730498] [<79010b65>] smp_trace_reschedule_interrupt+0x1c8/0x1d0 > [ 50.730979] [<798c720e>] trace_reschedule_interrupt+0x36/0x3c > [ 50.731214] [<7901875f>] ? native_safe_halt+0x5/0x7 > [ 50.731214] [<790085cc>] default_idle+0xb1/0x1e2 > [ 50.731214] [<79008d05>] arch_cpu_idle+0xe/0x10 > [ 50.731214] [<79069ddf>] cpu_startup_entry+0x1e4/0x2c3 > [ 50.731214] [<798adb34>] rest_init+0x12c/0x132 > [ 50.731214] [<798ada08>] ? __read_lock_failed+0x14/0x14 > [ 50.731214] [<79d309e4>] start_kernel+0x38d/0x393 > [ 50.731214] [<79d30489>] ? repair_env_string+0x51/0x51 > [ 50.731214] [<79d302c3>] i386_start_kernel+0x79/0x7d > [ 50.771947] OK > [ 50.772099] Testing event reschedule_entry: OK > > Signed-off-by: Seiji Aguchi <seiji.aguchi@....com> Reviewed-by: Steven Rostedt <rostedt@...dmis.org> -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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