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Date: Mon, 24 Jun 2013 20:23:00 +0000 From: Seiji Aguchi <seiji.aguchi@....com> To: Fengguang Wu <fengguang.wu@...el.com> CC: "H. Peter Anvin" <hpa@...ux.intel.com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: RE: [tip/x86/trace] INFO: suspicious RCU usage. I just sent the fix below. [PATCH -tip] x86,trace: Add rcu_irq_enter/exit() in smp_trace_reschedule_interrupt() > -----Original Message----- > From: Fengguang Wu [mailto:fengguang.wu@...el.com] > Sent: Saturday, June 22, 2013 8:36 PM > To: fengguang.wu@...el.com; Seiji Aguchi > Cc: H. Peter Anvin; linux-kernel@...r.kernel.org > Subject: [tip/x86/trace] INFO: suspicious RCU usage. > > Greetings, > > I got the below dmesg and the first bad commit is > > commit cf910e83ae23692fdeefc7e506e504c4c468d38a > Author: Seiji Aguchi <seiji.aguchi@....com> > Date: Thu Jun 20 11:46:53 2013 -0400 > > x86, trace: Add irq vector tracepoints > > [Purpose of this patch] > > As Vaibhav explained in the thread below, tracepoints for irq vectors > are useful. > > http://www.spinics.net/lists/mm-commits/msg85707.html > > <snip> > The current interrupt traces from irq_handler_entry and irq_handler_exit > provide when an interrupt is handled. They provide good data about when > the system has switched to kernel space and how it affects the currently > running processes. > > There are some IRQ vectors which trigger the system into kernel space, > which are not handled in generic IRQ handlers. Tracing such events gives > us the information about IRQ interaction with other system events. > > The trace also tells where the system is spending its time. We want to > know which cores are handling interrupts and how they are affecting other > processes in the system. Also, the trace provides information about when > the cores are idle and which interrupts are changing that state. > <snip> > > On the other hand, my usecase is tracing just local timer event and > getting a value of instruction pointer. > > I suggested to add an argument local timer event to get instruction pointer before. > But there is another way to get it with external module like systemtap. > So, I don't need to add any argument to irq vector tracepoints now. > > [Patch Description] > > Vaibhav's patch shared a trace point ,irq_vector_entry/irq_vector_exit, in all events. > But there is an above use case to trace specific irq_vector rather than tracing all events. > In this case, we are concerned about overhead due to unwanted events. > > So, add following tracepoints instead of introducing irq_vector_entry/exit. > so that we can enable them independently. > - local_timer_vector > - reschedule_vector > - call_function_vector > - call_function_single_vector > - irq_work_entry_vector > - error_apic_vector > - thermal_apic_vector > - threshold_apic_vector > - spurious_apic_vector > - x86_platform_ipi_vector > > Also, introduce a logic switching IDT at enabling/disabling time so that a time penalty > makes a zero when tracepoints are disabled. Detailed explanations are as follows. > - Create trace irq handlers with entering_irq()/exiting_irq(). > - Create a new IDT, trace_idt_table, at boot time by adding a logic to > _set_gate(). It is just a copy of original idt table. > - Register the new handlers for tracpoints to the new IDT by introducing > macros to alloc_intr_gate() called at registering time of irq_vector handlers. > - Add checking, whether irq vector tracing is on/off, into load_current_idt(). > This has to be done below debug checking for these reasons. > - Switching to debug IDT may be kicked while tracing is enabled. > - On the other hands, switching to trace IDT is kicked only when debugging > is disabled. > > In addition, the new IDT is created only when CONFIG_TRACING is enabled to avoid being > used for other purposes. > > Signed-off-by: Seiji Aguchi <seiji.aguchi@....com> > Link: http://lkml.kernel.org/r/51C323ED.5050708@hds.com > Signed-off-by: H. Peter Anvin <hpa@...ux.intel.com> > Cc: Steven Rostedt <rostedt@...dmis.org> > > [ 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 > > git bisect start cf910e83ae23692fdeefc7e506e504c4c468d38a v3.9 -- > git bisect good fbcd4836d20a33209843dcf84f83a33b97b74c9a # 16:16 52+ [SCSI] qla4xxx: Assign values using correct datatype > git bisect good 91f8575685e35f3bd021286bc82d26397458f5a9 # 17:09 52+ Merge branch 'for-linus' of > git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client > git bisect good c4cc75c3321cad6f20d1e5325293890255c8a663 # 20:03 52+ Merge git://git.infradead.org/users/eparis/audit > git bisect good 3a5395b3d57b9e3836c755434c88f4590d5ea6f6 # 20:17 52+ net: ethernet: xilinx_emaclite: set protocol selector bits > when writing ANAR > git bisect good e6395b68ad09a835f058da31bad0fe23d3882659 # 20:28 52+ Merge tag 'for-linus-v3.10-rc5' of > git://oss.sgi.com/xfs/xfs > git bisect good 5402b8047b0d286b6501f9097891cbf1e06daa3a # 20:40 52+ lib/mpi/mpicoder.c: looping issue, need stop when equal > to zero, found by 'EXTRA_FLAGS=-W'. > git bisect good 2dc85bf323515e59e15dfa858d1472bb25cad0fe # 20:53 52+ packet: packet_getname_spkt: make sure string is always > 0-terminated > git bisect good 3ad2e318a24124c53cc6390b5bfbd7613d9c2145 # 21:06 52+ Merge tag 'usb-3.10-rc5' of > git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb > git bisect good 5938930e71affa390c3fa33fa2fda52f58f850e8 # 21:17 52+ Merge branch 'merge' of > git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc > git bisect good 323226bbb3d865af12644d66df2b7f161adf51c7 # 21:30 52+ Merge tag 'fixes-3.10-4' of > git://git.infradead.org/users/jcooper/linux into fixes > git bisect good dd019897358b815f7828dab90b51d51df4d3658d # 21:40 52+ net: sh_eth: fix incorrect RX length error if R8A7740 > git bisect good e6694d984adbe8146d2f1e08d500befc1481835e # 22:02 52+ Merge tag 'fixes-for-linus' of > git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc > git bisect good f5abaa1bfc3dbf26d19d3513f39279ca369f8d65 # 22:13 52+ tracing: Add DEFINE_EVENT_FN() macro > git bisect good 629f4f9d59a27d8e58aa612e886e6a9a63ea7aeb # 22:24 52+ x86: Rename variables for debugging > git bisect good 629f4f9d59a27d8e58aa612e886e6a9a63ea7aeb # 22:31 156+ x86: Rename variables for debugging > git bisect bad 83ab85140bc1492f92de263a1c30ea04a0f465f7 # 22:31 0- trace,x86: Move creation of irq tracepoints from apic.c to > irq.c > git bisect good f71194a7d47c1da787555d27aac63973ca72323b # 22:36 156+ Merge branch 'x86/urgent' of > git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip > git bisect good a92a990789849502897e3e19c2c0e5154888edf7 # 23:55 156+ Merge branch 'perf/core' > > Thanks, > Fengguang -- 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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