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![]() Impact: fix incorrect locking triggered during hotplug-intense stress-tests While migrating the the CB_IRQSAFE_UNLOCKED timers during a cpu-offline, we queue them on the cb_pending list, so that they won't go stale. Thus, when the callbacks of the timers run from the softirq context, they could run into potential deadlocks, since these callbacks assume that they're running with irq's disabled, thereby annoying lockdep! Fix this by emulating hardirq context while running these callbacks from the hrtimer softirq. ================================= [ INFO: inconsistent lock state ] 2.6.27 #2 -------------------------------- inconsistent {in-hardirq-W} -> {hardirq-on-W} usage. ksoftirqd/0/4 [HC0[0]:SC1[1]:HE1:SE0] takes: (&rq->lock){++..}, at: [<c011db84>] sched_rt_period_timer+0x9e/0x1fc {in-hardirq-W} state was registered at: [<c014103c>] __lock_acquire+0x549/0x121e [<c0107890>] native_sched_clock+0x88/0x99 [<c013aa12>] clocksource_get_next+0x39/0x3f [<c0139abc>] update_wall_time+0x616/0x7df [<c0141d6b>] lock_acquire+0x5a/0x74 [<c0121724>] scheduler_tick+0x3a/0x18d [<c047ed45>] _spin_lock+0x1c/0x45 [<c0121724>] scheduler_tick+0x3a/0x18d [<c0121724>] scheduler_tick+0x3a/0x18d [<c012c436>] update_process_times+0x3a/0x44 [<c013c044>] tick_periodic+0x63/0x6d [<c013c062>] tick_handle_periodic+0x14/0x5e [<c010568c>] timer_interrupt+0x44/0x4a [<c0150c9f>] handle_IRQ_event+0x13/0x3d [<c0151c14>] handle_level_irq+0x79/0xbd [<c0105634>] do_IRQ+0x69/0x7d [<c01041e4>] common_interrupt+0x28/0x30 [<c047007b>] aac_probe_one+0x1a3/0x3f3 [<c047ec2d>] _spin_unlock_irqrestore+0x36/0x39 [<c01512b4>] setup_irq+0x1be/0x1f9 [<c065d70b>] start_kernel+0x259/0x2c5 [<ffffffff>] 0xffffffff irq event stamp: 50102 hardirqs last enabled at (50102): [<c047ebf4>] _spin_unlock_irq+0x20/0x23 hardirqs last disabled at (50101): [<c047edc2>] _spin_lock_irq+0xa/0x4b softirqs last enabled at (50088): [<c0128ba6>] do_softirq+0x37/0x4d softirqs last disabled at (50099): [<c0128ba6>] do_softirq+0x37/0x4d other info that might help us debug this: no locks held by ksoftirqd/0/4. stack backtrace: Pid: 4, comm: ksoftirqd/0 Not tainted 2.6.27 #2 [<c013f6cb>] print_usage_bug+0x13e/0x147 [<c013fef5>] mark_lock+0x493/0x797 [<c01410b1>] __lock_acquire+0x5be/0x121e [<c0141d6b>] lock_acquire+0x5a/0x74 [<c011db84>] sched_rt_period_timer+0x9e/0x1fc [<c047ed45>] _spin_lock+0x1c/0x45 [<c011db84>] sched_rt_period_timer+0x9e/0x1fc [<c011db84>] sched_rt_period_timer+0x9e/0x1fc [<c01210fd>] finish_task_switch+0x41/0xbd [<c0107890>] native_sched_clock+0x88/0x99 [<c011dae6>] sched_rt_period_timer+0x0/0x1fc [<c0136dda>] run_hrtimer_pending+0x54/0xe5 [<c011dae6>] sched_rt_period_timer+0x0/0x1fc [<c0128afb>] __do_softirq+0x7b/0xef [<c0128ba6>] do_softirq+0x37/0x4d [<c0128c12>] ksoftirqd+0x56/0xc5 [<c0128bbc>] ksoftirqd+0x0/0xc5 [<c0134649>] kthread+0x38/0x5d [<c0134611>] kthread+0x0/0x5d [<c0104477>] kernel_thread_helper+0x7/0x10 ======================= Signed-off-by: Gautham R Shenoy <ego@in.ibm.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> |
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irq | ||
power | ||
time | ||
trace | ||
.gitignore | ||
acct.c | ||
audit.c | ||
audit.h | ||
audit_tree.c | ||
auditfilter.c | ||
auditsc.c | ||
backtracetest.c | ||
bounds.c | ||
capability.c | ||
cgroup.c | ||
cgroup_debug.c | ||
cgroup_freezer.c | ||
compat.c | ||
configs.c | ||
cpu.c | ||
cpuset.c | ||
delayacct.c | ||
dma-coherent.c | ||
dma.c | ||
exec_domain.c | ||
exit.c | ||
extable.c | ||
fork.c | ||
freezer.c | ||
futex.c | ||
futex_compat.c | ||
hrtimer.c | ||
itimer.c | ||
kallsyms.c | ||
Kconfig.freezer | ||
Kconfig.hz | ||
Kconfig.preempt | ||
kexec.c | ||
kfifo.c | ||
kgdb.c | ||
kmod.c | ||
kprobes.c | ||
ksysfs.c | ||
kthread.c | ||
latencytop.c | ||
lockdep.c | ||
lockdep_internals.h | ||
lockdep_proc.c | ||
Makefile | ||
marker.c | ||
module.c | ||
mutex-debug.c | ||
mutex-debug.h | ||
mutex.c | ||
mutex.h | ||
notifier.c | ||
ns_cgroup.c | ||
nsproxy.c | ||
panic.c | ||
params.c | ||
pid.c | ||
pid_namespace.c | ||
pm_qos_params.c | ||
posix-cpu-timers.c | ||
posix-timers.c | ||
printk.c | ||
profile.c | ||
ptrace.c | ||
rcuclassic.c | ||
rcupdate.c | ||
rcupreempt.c | ||
rcupreempt_trace.c | ||
rcutorture.c | ||
relay.c | ||
res_counter.c | ||
resource.c | ||
rtmutex-debug.c | ||
rtmutex-debug.h | ||
rtmutex-tester.c | ||
rtmutex.c | ||
rtmutex.h | ||
rtmutex_common.h | ||
rwsem.c | ||
sched.c | ||
sched_clock.c | ||
sched_cpupri.c | ||
sched_cpupri.h | ||
sched_debug.c | ||
sched_fair.c | ||
sched_features.h | ||
sched_idletask.c | ||
sched_rt.c | ||
sched_stats.h | ||
seccomp.c | ||
semaphore.c | ||
signal.c | ||
smp.c | ||
softirq.c | ||
softlockup.c | ||
spinlock.c | ||
srcu.c | ||
stacktrace.c | ||
stop_machine.c | ||
sys.c | ||
sys_ni.c | ||
sysctl.c | ||
sysctl_check.c | ||
taskstats.c | ||
test_kprobes.c | ||
time.c | ||
timeconst.pl | ||
timer.c | ||
tracepoint.c | ||
tsacct.c | ||
uid16.c | ||
user.c | ||
user_namespace.c | ||
utsname.c | ||
utsname_sysctl.c | ||
wait.c | ||
workqueue.c |