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Thomas Gleixner 98d8256739 Prevent going idle with softirq pending 
The NOHZ patch contains a check for softirqs pending when a CPU goes idle.
The BUG is unrelated to NOHZ, it just was made visible by the NOHZ patch.
The BUG showed up mainly on P4 / hyperthreading enabled machines which lead
the investigations into the wrong direction in the first place.  The real
cause is in cond_resched_softirq():

cond_resched_softirq() is enabling softirqs without invoking the softirq
daemon when softirqs are pending.  This leads to the warning message in the
NOHZ idle code:

t1 runs softirq disabled code on CPU#0
interrupt happens, softirq is raised, but deferred (softirqs disabled)
t1 calls cond_resched_softirq()
	enables softirqs via _local_bh_enable()
	calls schedule()
t2 runs
t1 is migrated to CPU#1
t2 is done and invokes idle()
NOHZ detects the pending softirq

Fix: change _local_bh_enable() to local_bh_enable() so the softirq
daemon is invoked.

Thanks to Anant Nitya for debugging this with great patience !

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-23 20:14:15 -07:00
..
irq [IA64] SN: validate smp_affinity mask on intr redirect 2007-05-11 09:35:38 -07:00
power power: Fix sizeof(PAGE_SIZE) typo 2007-05-23 20:14:14 -07:00
time NOHZ: Rate limit the local softirq pending warning output 2007-05-23 20:14:11 -07:00
.gitignore
acct.c
audit.c audit: add spaces on either side of case "..." operator. 2007-05-08 11:15:09 -07:00
audit.h [PATCH] audit signal recipients 2007-05-11 05:38:25 -04:00
auditfilter.c audit_match_signal() and friends are used only if CONFIG_AUDITSYSCALL is set 2007-05-15 18:56:37 -07:00
auditsc.c [PATCH] Abnormal End of Processes 2007-05-11 05:38:26 -04:00
capability.c [PATCH] pid: replace do/while_each_task_pid with do/while_each_pid_task 2007-02-12 09:48:32 -08:00
compat.c signal/timer/event: timerfd compat code 2007-05-11 08:29:36 -07:00
configs.c use simple_read_from_buffer in kernel/ 2007-05-09 12:30:49 -07:00
cpu.c microcode: use suspend-related CPU hotplug notifications 2007-05-09 12:30:56 -07:00
cpuset.c use simple_read_from_buffer in kernel/ 2007-05-09 12:30:49 -07:00
delayacct.c KMEM_CACHE(): simplify slab cache creation 2007-05-07 12:12:55 -07:00
die_notifier.c move die notifier handling to common code 2007-05-08 11:15:04 -07:00
dma.c
exec_domain.c
exit.c recalc_sigpending_tsk fixes 2007-05-23 20:14:12 -07:00
extable.c
fork.c freezer: fix vfork problem 2007-05-23 20:14:11 -07:00
futex_compat.c futex_requeue_pi optimization 2007-05-09 12:30:55 -07:00
futex.c FUTEX: new PRIVATE futexes 2007-05-09 12:30:55 -07:00
hrtimer.c Add suspend-related notifications for CPU hotplug 2007-05-09 12:30:56 -07:00
itimer.c The scheduled -EINVAL for invalid timevals in setitimer 2007-05-08 11:15:13 -07:00
kallsyms.c kallsyms: cleanup: use seq_release_private() where appropriate 2007-05-08 11:15:09 -07:00
Kconfig.hz
Kconfig.preempt Fix trivial typos in Kconfig* files 2007-05-09 07:12:20 +02:00
kexec.c kdump/kexec: calculate note size at compile time 2007-05-08 11:15:07 -07:00
kfifo.c [PATCH] Numerous fixes to kernel-doc info in source files. 2007-02-11 10:51:32 -08:00
kmod.c wait_for_helper: remove unneeded do_sigaction() 2007-05-09 12:30:53 -07:00
kprobes.c Kprobes: The ON/OFF knob thru debugfs 2007-05-08 11:15:19 -07:00
ksysfs.c remove "struct subsystem" as it is no longer needed 2007-05-02 18:57:59 -07:00
kthread.c freezer: fix kthread_create vs freezer theoretical race 2007-05-23 20:14:11 -07:00
latency.c
lockdep_internals.h
lockdep_proc.c [PATCH] remove many unneeded #includes of sched.h 2007-02-14 08:09:54 -08:00
lockdep.c lockdep: removed unused ip argument in mark_lock & mark_held_locks 2007-05-08 11:15:13 -07:00
Makefile move die notifier handling to common code 2007-05-08 11:15:04 -07:00
module.c Fix minor typoes in kernel/module.c 2007-05-09 07:26:28 +02:00
mutex-debug.c [PATCH] remove many unneeded #includes of sched.h 2007-02-14 08:09:54 -08:00
mutex-debug.h
mutex.c wrap access to thread_info 2007-05-09 12:30:56 -07:00
mutex.h
nsproxy.c Merge sys_clone()/sys_unshare() nsproxy and namespace handling 2007-05-08 11:15:00 -07:00
panic.c [PATCH] Add TAINT_USER and ability to set taint flags from userspace 2007-02-11 10:51:29 -08:00
params.c kernel/params.c: fix lying comment for param_array() 2007-05-08 11:15:08 -07:00
pid.c statically initialize struct pid for swapper 2007-05-11 08:29:35 -07:00
posix-cpu-timers.c Introduce a handy list_first_entry macro 2007-05-08 11:15:11 -07:00
posix-timers.c header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
printk.c header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
profile.c Detach sched.h from mm.h 2007-05-21 09:18:19 -07:00
ptrace.c [PATCH] auditing ptrace 2007-05-11 05:38:25 -04:00
rcupdate.c Add suspend-related notifications for CPU hotplug 2007-05-09 12:30:56 -07:00
rcutorture.c rcutorture: Remove redundant assignment to cur_ops in for loop 2007-05-08 11:15:17 -07:00
relay.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/bunk/trivial 2007-05-09 12:54:17 -07:00
resource.c libata/IDE: remove combined mode quirk 2007-04-28 14:15:59 -04:00
rtmutex_common.h futex_requeue_pi optimization 2007-05-09 12:30:55 -07:00
rtmutex-debug.c
rtmutex-debug.h
rtmutex-tester.c
rtmutex.c futex_requeue_pi optimization 2007-05-09 12:30:55 -07:00
rtmutex.h
rwsem.c Lockdep treats down_write_trylock like regular down_write 2007-05-08 11:15:09 -07:00
sched.c Prevent going idle with softirq pending 2007-05-23 20:14:15 -07:00
seccomp.c
signal.c recalc_sigpending_tsk fixes 2007-05-23 20:14:12 -07:00
softirq.c Add suspend-related notifications for CPU hotplug 2007-05-09 12:30:56 -07:00
softlockup.c Add suspend-related notifications for CPU hotplug 2007-05-09 12:30:56 -07:00
spinlock.c
srcu.c
stacktrace.c
stop_machine.c stop_machine() now uses hard_irq_disable 2007-05-11 08:29:34 -07:00
sys_ni.c compat signalfd and timerfd are cond syscalls 2007-05-12 10:55:40 -07:00
sys.c attach_pid() with struct pid parameter 2007-05-11 08:29:35 -07:00
sysctl.c make sysctl/kernel/core_pattern and fs/exec.c agree on maximum core filename size 2007-05-17 05:23:05 -07:00
taskstats.c KMEM_CACHE(): simplify slab cache creation 2007-05-07 12:12:55 -07:00
time.c header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
timer.c timekeeping fix patch got mis-applied 2007-05-14 12:13:11 -07:00
tsacct.c [PATCH] time: x86_64: split x86_64/kernel/time.c up 2007-02-16 08:14:00 -08:00
uid16.c header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
user.c
utsname_sysctl.c [PATCH] sysctl: remove insert_at_head from register_sysctl 2007-02-14 08:09:59 -08:00
utsname.c Merge sys_clone()/sys_unshare() nsproxy and namespace handling 2007-05-08 11:15:00 -07:00
wait.c Fix occurrences of "the the " 2007-05-09 08:57:56 +02:00
workqueue.c simplify cleanup_workqueue_thread() 2007-05-23 20:14:13 -07:00