Messages in this thread | | | Subject | Re: [GIT PULL] RCU changes for v3.3 | From | Eric Dumazet <> | Date | Tue, 24 Jan 2012 20:57:49 +0100 |
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Le mardi 24 janvier 2012 à 11:41 -0800, Paul E. McKenney a écrit :
> Ah, I see... I need to find one of trace_power_start(), > trace_power_frequency(), or trace_power_end(). I would have to guess > that this is either the trace_power_start() or the trace_power_end() > called from drivers/cpuidle/cpuidle.c lines 97 and 102. Those are > within cpuidle_idle_call(), which are called from cpu_idle() in > arch/x86/kernel/process_32.c and arch/x86/kernel/process_64.c, so this > sounds plausible. > > And they are indeed busted -- RCU believes the CPU is idle at the point > that cpuidle_idle_call() is invoked. > > A hacky patch is below. Here are some of my concerns with it: > > 1. Is there a configuration in which the scheduler clock gets > turned off, but in which cpuidle_idle_call() always returns > zero? If so, we either really need RCU to consider the entire > inner loop to be idle (thus needing to snapshot the value of > cpuidle_idle_call() in the outer loop) or we need explicit calls > to rcu_sched_qs() and friends. > > Yes, we could momentarily exit RCU idleness mode, but I would > need to think that one through... > > 2. I am not totally confident that I have the order of operations > surrounding the call to pm_idle() correct. > > 3. This only addresses x86, and it looks like a few other architectures > have this same problem. > > 4. Probably other things that I haven't thought of. > > That said, the patch does seem to compile, at least on my 32-bit > laptop... > > Thanx, Paul > > ------------------------------------------------------------------------ > > idle: Avoid using RCU when RCU thinks the CPU is idle > > The x86 idle loops invoke cpuidle_idle_call() which uses tracing > which uses RCU. Unfortunately, these idle loops have already > told RCU to ignore this CPU when they call it. This patch hacks > the idle loops to avoid this problem, but probably causing several > other problems in the process. > > Not-yet-signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > ---
Hi Paul
Just tested it on my x86_64 machine, but warnings are still here
Thanks !
[ 61.111559] [ 61.111563] =============================== [ 61.111565] [ INFO: suspicious RCU usage. ] [ 61.111567] 3.3.0-rc1+ #572 Not tainted [ 61.111569] ------------------------------- [ 61.111571] include/trace/events/power.h:102 suspicious rcu_dereference_check() usage! [ 61.111573] [ 61.111574] other info that might help us debug this: [ 61.111575] [ 61.111577] [ 61.111577] rcu_scheduler_active = 1, debug_locks = 1 [ 61.111579] RCU used illegally from extended quiescent state! [ 61.111582] no locks held by swapper/0/0. [ 61.111583] [ 61.111584] stack backtrace: [ 61.111587] Pid: 0, comm: swapper/0 Not tainted 3.3.0-rc1+ #572 [ 61.111589] Call Trace: [ 61.111598] [<ffffffff810949ba>] lockdep_rcu_suspicious+0xca/0xf0 [ 61.111604] [<ffffffff8100abb9>] mwait_idle+0x499/0x4c0 [ 61.111609] [<ffffffff810011e8>] cpu_idle+0x98/0xe0 [ 61.111615] [<ffffffff8174f49f>] rest_init+0x133/0x144 [ 61.111618] [<ffffffff8174f3e5>] ? rest_init+0x79/0x144 [ 61.111623] [<ffffffff81cc2b51>] start_kernel+0x35b/0x366 [ 61.111627] [<ffffffff81cc2321>] x86_64_start_reservations+0x131/0x135 [ 61.111631] [<ffffffff81cc2415>] x86_64_start_kernel+0xf0/0xf7 [ 61.111743] ------------[ cut here ]------------ [ 61.111750] WARNING: at include/linux/rcupdate.h:242 __perf_event_overflow+0x27c/0x2c0() [ 61.111754] Hardware name: ProLiant BL460c G6 [ 61.111756] Modules linked in: ipmi_devintf nfsd exportfs hpilo ipmi_si bnx2x crc32c libcrc32c mdio [last unloaded: scsi_wait_scan] [ 61.111770] Pid: 0, comm: swapper/0 Not tainted 3.3.0-rc1+ #572 [ 61.111772] Call Trace: [ 61.111777] [<ffffffff81038eaf>] warn_slowpath_common+0x7f/0xc0 [ 61.111781] [<ffffffff81038f0a>] warn_slowpath_null+0x1a/0x20 [ 61.111784] [<ffffffff810f8ebc>] __perf_event_overflow+0x27c/0x2c0 [ 61.111788] [<ffffffff817711ae>] ? printk+0x41/0x43 [ 61.111794] [<ffffffff810a1f86>] ? __module_text_address+0x16/0x80 [ 61.111798] [<ffffffff810f8fa9>] perf_swevent_overflow+0xa9/0xc0 [ 61.111801] [<ffffffff810f902f>] perf_swevent_event+0x6f/0x90 [ 61.111804] [<ffffffff810f90c6>] perf_tp_event+0x76/0xf0 [ 61.111809] [<ffffffff810f14ce>] perf_trace_power+0xbe/0xe0 [ 61.111812] [<ffffffff8100ab2f>] ? mwait_idle+0x40f/0x4c0 [ 61.111815] [<ffffffff8100ab2f>] mwait_idle+0x40f/0x4c0 [ 61.111819] [<ffffffff810011e8>] cpu_idle+0x98/0xe0 [ 61.111822] [<ffffffff8174f49f>] rest_init+0x133/0x144 [ 61.111825] [<ffffffff8174f3e5>] ? rest_init+0x79/0x144 [ 61.111828] [<ffffffff81cc2b51>] start_kernel+0x35b/0x366 [ 61.111831] [<ffffffff81cc2321>] x86_64_start_reservations+0x131/0x135 [ 61.111834] [<ffffffff81cc2415>] x86_64_start_kernel+0xf0/0xf7 [ 61.111837] ---[ end trace 18a36211154afbbb ]--- [ 61.111839] ------------[ cut here ]------------ [ 61.111843] WARNING: at include/linux/rcupdate.h:242 perf_output_begin+0x2f6/0x330() [ 61.111845] Hardware name: ProLiant BL460c G6 [ 61.111848] Modules linked in: ipmi_devintf nfsd exportfs hpilo ipmi_si bnx2x crc32c libcrc32c mdio [last unloaded: scsi_wait_scan] [ 61.111859] Pid: 0, comm: swapper/0 Tainted: G W 3.3.0-rc1+ #572 [ 61.111861] Call Trace: [ 61.111864] [<ffffffff81038eaf>] warn_slowpath_common+0x7f/0xc0 [ 61.111868] [<ffffffff81038f0a>] warn_slowpath_null+0x1a/0x20 [ 61.111871] [<ffffffff810fc286>] perf_output_begin+0x2f6/0x330 [ 61.111875] [<ffffffff81076975>] ? sched_clock_cpu+0xc5/0x120 [ 61.111879] [<ffffffff8109371d>] ? trace_hardirqs_off+0xd/0x10 [ 61.111882] [<ffffffff81076a1f>] ? local_clock+0x4f/0x60 [ 61.111886] [<ffffffff810f21cd>] ? __perf_event_header__init_id+0xad/0xf0 [ 61.111889] [<ffffffff810f8b93>] ? perf_prepare_sample+0x63/0x110 [ 61.111892] [<ffffffff810f8dcd>] __perf_event_overflow+0x18d/0x2c0 [ 61.111895] [<ffffffff810f8d85>] ? __perf_event_overflow+0x145/0x2c0 [ 61.111898] [<ffffffff817711ae>] ? printk+0x41/0x43 [ 61.111901] [<ffffffff810f8fa9>] perf_swevent_overflow+0xa9/0xc0 [ 61.111904] [<ffffffff810f902f>] perf_swevent_event+0x6f/0x90 [ 61.111907] [<ffffffff810f90c6>] perf_tp_event+0x76/0xf0 [ 61.111911] [<ffffffff810f14ce>] perf_trace_power+0xbe/0xe0 [ 61.111915] [<ffffffff8100ab2f>] ? mwait_idle+0x40f/0x4c0 [ 61.111918] [<ffffffff8100ab2f>] mwait_idle+0x40f/0x4c0 [ 61.111922] [<ffffffff810011e8>] cpu_idle+0x98/0xe0 [ 61.111926] [<ffffffff8174f49f>] rest_init+0x133/0x144 [ 61.111929] [<ffffffff8174f3e5>] ? rest_init+0x79/0x144 [ 61.111933] [<ffffffff81cc2b51>] start_kernel+0x35b/0x366 [ 61.111937] [<ffffffff81cc2321>] x86_64_start_reservations+0x131/0x135 [ 61.111940] [<ffffffff81cc2415>] x86_64_start_kernel+0xf0/0xf7 [ 61.111943] ---[ end trace 18a36211154afbbc ]--- [ 61.111946] [ 61.111947] =============================== [ 61.111949] [ INFO: suspicious RCU usage. ] [ 61.111950] 3.3.0-rc1+ #572 Tainted: G W [ 61.111952] ------------------------------- [ 61.111954] kernel/events/ring_buffer.c:120 suspicious rcu_dereference_check() usage! [ 61.111956] [ 61.111957] other info that might help us debug this: [ 61.111958] [ 61.111960] [ 61.111960] rcu_scheduler_active = 1, debug_locks = 1 [ 61.111962] RCU used illegally from extended quiescent state! [ 61.111964] 2 locks held by swapper/0/0: [ 61.111966] #0: (rcu_read_lock){.+.+..}, at: [<ffffffff810f8d85>] __perf_event_overflow+0x145/0x2c0 [ 61.111974] #1: (rcu_read_lock){.+.+..}, at: [<ffffffff810fbfcf>] perf_output_begin+0x3f/0x330 [ 61.111980] [ 61.111980] stack backtrace: [ 61.111982] Pid: 0, comm: swapper/0 Tainted: G W 3.3.0-rc1+ #572 [ 61.111984] Call Trace: [ 61.111987] [<ffffffff810949ba>] lockdep_rcu_suspicious+0xca/0xf0 [ 61.111990] [<ffffffff810fc1f8>] perf_output_begin+0x268/0x330 [ 61.111993] [<ffffffff810fbfcf>] ? perf_output_begin+0x3f/0x330 [ 61.111997] [<ffffffff81076975>] ? sched_clock_cpu+0xc5/0x120 [ 61.111999] [<ffffffff8109371d>] ? trace_hardirqs_off+0xd/0x10 [ 61.112003] [<ffffffff81076a1f>] ? local_clock+0x4f/0x60 [ 61.112006] [<ffffffff810f21cd>] ? __perf_event_header__init_id+0xad/0xf0 [ 61.112009] [<ffffffff810f8b93>] ? perf_prepare_sample+0x63/0x110 [ 61.112013] [<ffffffff810f8dcd>] __perf_event_overflow+0x18d/0x2c0 [ 61.112015] [<ffffffff810f8d85>] ? __perf_event_overflow+0x145/0x2c0 [ 61.112019] [<ffffffff817711ae>] ? printk+0x41/0x43 [ 61.112022] [<ffffffff810f8fa9>] perf_swevent_overflow+0xa9/0xc0 [ 61.112024] [<ffffffff810f902f>] perf_swevent_event+0x6f/0x90 [ 61.112028] [<ffffffff810f90c6>] perf_tp_event+0x76/0xf0 [ 61.112031] [<ffffffff810f14ce>] perf_trace_power+0xbe/0xe0 [ 61.112034] [<ffffffff8100ab2f>] ? mwait_idle+0x40f/0x4c0 [ 61.112038] [<ffffffff8100ab2f>] mwait_idle+0x40f/0x4c0 [ 61.112041] [<ffffffff810011e8>] cpu_idle+0x98/0xe0 [ 61.112044] [<ffffffff8174f49f>] rest_init+0x133/0x144 [ 61.112047] [<ffffffff8174f3e5>] ? rest_init+0x79/0x144 [ 61.112050] [<ffffffff81cc2b51>] start_kernel+0x35b/0x366 [ 61.112053] [<ffffffff81cc2321>] x86_64_start_reservations+0x131/0x135 [ 61.112057] [<ffffffff81cc2415>] x86_64_start_kernel+0xf0/0xf7 [ 61.112059] ------------[ cut here ]------------ [ 61.112062] WARNING: at include/linux/rcupdate.h:248 perf_output_end+0x5b/0x70() [ 61.112064] Hardware name: ProLiant BL460c G6 [ 61.112065] Modules linked in: ipmi_devintf nfsd exportfs hpilo ipmi_si bnx2x crc32c libcrc32c mdio [last unloaded: scsi_wait_scan] [ 61.112076] Pid: 0, comm: swapper/0 Tainted: G W 3.3.0-rc1+ #572 [ 61.112078] Call Trace: [ 61.112081] [<ffffffff81038eaf>] warn_slowpath_common+0x7f/0xc0 [ 61.112085] [<ffffffff81038f0a>] warn_slowpath_null+0x1a/0x20 [ 61.112088] [<ffffffff810fc31b>] perf_output_end+0x5b/0x70 [ 61.112091] [<ffffffff810f8e6c>] __perf_event_overflow+0x22c/0x2c0 [ 61.112094] [<ffffffff810f8d85>] ? __perf_event_overflow+0x145/0x2c0 [ 61.112097] [<ffffffff810f8fa9>] perf_swevent_overflow+0xa9/0xc0 [ 61.112101] [<ffffffff810f902f>] perf_swevent_event+0x6f/0x90 [ 61.112104] [<ffffffff810f90c6>] perf_tp_event+0x76/0xf0 [ 61.112107] [<ffffffff810f14ce>] perf_trace_power+0xbe/0xe0 [ 61.112110] [<ffffffff8100ab2f>] ? mwait_idle+0x40f/0x4c0 [ 61.112113] [<ffffffff8100ab2f>] mwait_idle+0x40f/0x4c0 [ 61.112116] [<ffffffff810011e8>] cpu_idle+0x98/0xe0 [ 61.112120] [<ffffffff8174f49f>] rest_init+0x133/0x144 [ 61.112122] ------------[ cut here ]------------ [ 61.112126] WARNING: at include/linux/rcupdate.h:248 perf_output_end+0x5b/0x70() [ 61.112128] Hardware name: ProLiant BL460c G6 [ 61.112129] Modules linked in: ipmi_devintf nfsd exportfs hpilo [<ffffffff8174f3e5>] ? rest_init+0x79/0x144 [ 61.112137] [<ffffffff81cc2b51>] start_kernel+0x35b/0x366 [ 61.112138] ipmi_si bnx2x [<ffffffff81cc2321>] x86_64_start_reservations+0x131/0x135 [ 61.112143] crc32c libcrc32c mdio [last unloaded: scsi_wait_scan] [ 61.112148] Pid: 0, comm: swapper/2 Tainted: G W 3.3.0-rc1+ #572 [ 61.112150] [<ffffffff81cc2415>] x86_64_start_kernel+0xf0/0xf7 [ 61.112152] ---[ end trace 18a36211154afbbd ]--- [ 61.112153] ------------[ cut here ]------------ [ 61.112155] WARNING: at include/linux/rcupdate.h:248 __perf_event_overflow+0x2a6/0x2c0() [ 61.112156] Hardware name: ProLiant BL460c G6 [ 61.112157] Modules linked in: ipmi_devintf nfsd exportfs hpilo ipmi_si bnx2x crc32c libcrc32c mdio [last unloaded: scsi_wait_scan] [ 61.112165] Pid: 0, comm: swapper/0 Tainted: G W 3.3.0-rc1+ #572 [ 61.112166] Call Trace: [ 61.112168] [<ffffffff81038eaf>] warn_slowpath_common+0x7f/0xc0 [ 61.112170] Call Trace: [ 61.112172] [<ffffffff81038f0a>] warn_slowpath_null+0x1a/0x20 [ 61.112176] [<ffffffff81038eaf>] warn_slowpath_common+0x7f/0xc0 [ 61.112178] [<ffffffff810f8ee6>] __perf_event_overflow+0x2a6/0x2c0 [ 61.112182] [<ffffffff81038f0a>] warn_slowpath_null+0x1a/0x20 [ 61.112184] [<ffffffff810f8d85>] ? __perf_event_overflow+0x145/0x2c0 [ 61.112186] [<ffffffff810f8fa9>] perf_swevent_overflow+0xa9/0xc0 [ 61.112189] [<ffffffff810fc31b>] perf_output_end+0x5b/0x70 [ 61.112191] [<ffffffff810f902f>] perf_swevent_event+0x6f/0x90 [ 61.112193] [<ffffffff810f90c6>] perf_tp_event+0x76/0xf0 [ 61.112196] [<ffffffff810f8e6c>] __perf_event_overflow+0x22c/0x2c0 [ 61.112199] [<ffffffff810f14ce>] perf_trace_power+0xbe/0xe0 [ 61.112202] [<ffffffff8100ab2f>] ? mwait_idle+0x40f/0x4c0 [ 61.112205] [<ffffffff810f8d85>] ? __perf_event_overflow+0x145/0x2c0 [ 61.112207] [<ffffffff8100ab2f>] mwait_idle+0x40f/0x4c0 [ 61.112209] [<ffffffff810011e8>] cpu_idle+0x98/0xe0 [ 61.112212] [<ffffffff8174f49f>] rest_init+0x133/0x144 [ 61.112214] [<ffffffff810f8fa9>] perf_swevent_overflow+0xa9/0xc0 [ 61.112217] [<ffffffff810f902f>] perf_swevent_event+0x6f/0x90 [ 61.112219] [<ffffffff8174f3e5>] ? rest_init+0x79/0x144 [ 61.112222] [<ffffffff810f90c6>] perf_tp_event+0x76/0xf0 [ 61.112227] [<ffffffff8102009d>] ? lapic_next_event+0x1d/0x30 [ 61.112229] [<ffffffff81cc2b51>] start_kernel+0x35b/0x366 [ 61.112232] [<ffffffff81cc2321>] x86_64_start_reservations+0x131/0x135 [ 61.112235] [<ffffffff810f14ce>] perf_trace_power+0xbe/0xe0 [ 61.112238] [<ffffffff81cc2415>] x86_64_start_kernel+0xf0/0xf7 [ 61.112239] ---[ end trace 18a36211154afbbe ]--- [ 61.112242] [<ffffffff8100ab2f>] ? mwait_idle+0x40f/0x4c0 [ 61.112245] [<ffffffff8100ab2f>] mwait_idle+0x40f/0x4c0 [ 61.112248] [<ffffffff810011e8>] cpu_idle+0x98/0xe0 [ 61.112252] [<ffffffff8176baee>] start_secondary+0x1df/0x1e3 [ 61.112254] ---[ end trace 18a36211154afbbf ]--- [ 61.114605] [ 61.114608] =============================== [ 61.114611] [ INFO: suspicious RCU usage. ] [ 61.114614] 3.3.0-rc1+ #572 Tainted: G W [ 61.114616] ------------------------------- [ 61.114620] include/trace/events/power.h:127 suspicious rcu_dereference_check() usage! [ 61.114625] [ 61.114626] other info that might help us debug this: [ 61.114628] [ 61.114630] [ 61.114630] rcu_scheduler_active = 1, debug_locks = 1 [ 61.114633] RCU used illegally from extended quiescent state! [ 61.114635] no locks held by swapper/2/0. [ 61.114637] [ 61.114638] stack backtrace: [ 61.114641] Pid: 0, comm: swapper/2 Tainted: G W 3.3.0-rc1+ #572 [ 61.114645] Call Trace: [ 61.114650] [<ffffffff810949ba>] lockdep_rcu_suspicious+0xca/0xf0 [ 61.114655] [<ffffffff8100a9cd>] mwait_idle+0x2ad/0x4c0 [ 61.114660] [<ffffffff810011e8>] cpu_idle+0x98/0xe0 [ 61.114664] [<ffffffff8176baee>] start_secondary+0x1df/0x1e3
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