Kernel error messsage - NOHZ: local_softirq_pending 100

[oshunluvr]

Any geniuses out there know what this means? Just started showing up in my kernel log (yes, I actually look once in awhile!).

NOHZ: local_softirq_pending 100

Only happens once a day or so, just never seen it before. Web searching reveals little reference to it except that it exists.

[oblivion]

Re: Kernel error messsage - NOHZ: local_softirq_pending 100

Hello oshunluvr,

Forgive me If I'm posting something you already know ( I don't want to be "captain obvious" here ), could this be of any help to you?:

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

================================================== =================
--- linux.orig/kernel/sched.c
+++ linux/kernel/sched.c
@@ -4212,9 +4212,7 @@ int __sched cond_resched_softirq(void)
BUG_ON(!in_softirq());

if (need_resched() && system_state == SYSTEM_RUNNING) {
raw_local_irq_disable();
_local_bh_enable();- raw_local_irq_enable();
local_bh_enable();
__cond_resched();
local_bh_disable();
return 1;

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

Here is the original link:

http://lkml.org/lkml/2007/5/22/35

I know that this is an old link, but it seems that this "patch" might be what you are looking for (though, you may need to recompile kernel)

Regards