Messages in this thread | | | Date | Tue, 8 Dec 2009 18:08:34 -0800 | From | "Paul E. McKenney" <> | Subject | Re: Badness at kernel/rcutree.c:1228 |
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On Wed, Dec 09, 2009 at 03:41:00AM +0200, kordex - wrote: > Hey, > > I put the debug function under init/main.c after rcu_init(); but there > is no output on dmesg which means that it receives zero value. > > Full dmesg: http://xnet.fi/opt/apps/lkml-2.6.32-vanilla.dmesg.rcu-init.txt
Could you please send the patch you applied to, as you said, put the debug function under init/main.c after rcu_init()?
Thanx, Paul
> --Mikko Kortelainen > > 2009/12/8 Paul E. McKenney <paulmck@linux.vnet.ibm.com>: > > On Tue, Dec 08, 2009 at 11:22:07AM -0800, Paul E. McKenney wrote: > >> At this point, I must defer to those more skilled than I at diagnosing > >> early-boot problems. > > > > Well, that is silly on my part -- the problem seems to appear late in > > boot, and you had no problem capturing that portion of the boot log. > > > > So please see below for a patch providing a rcu_check_beenonline() > > function that, when called after rcu_init(), returns non-zero if the > > beenonline fields have become corrupted. So put calls of the form: > > > > WARN_ON_ONCE(rcu_check_beenonline()); > > > > in the initialization code path preceding the problem. Either #include > > rcupdate.h or explicitly declare the function as appropriate. > > > > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > --- > > > > diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h > > index 9642c6b..190a687 100644 > > --- a/include/linux/rcutree.h > > +++ b/include/linux/rcutree.h > > @@ -39,6 +39,8 @@ extern int rcu_cpu_notify(struct notifier_block *self, > > extern int rcu_needs_cpu(int cpu); > > extern int rcu_expedited_torture_stats(char *page); > > > > +extern int rcu_check_beenonline(void); > > + > > #ifdef CONFIG_TREE_PREEMPT_RCU > > > > extern void __rcu_read_lock(void); > > diff --git a/kernel/rcutree.c b/kernel/rcutree.c > > index 207125b..27d3722 100644 > > --- a/kernel/rcutree.c > > +++ b/kernel/rcutree.c > > @@ -77,6 +77,17 @@ DEFINE_PER_CPU(struct rcu_data, rcu_sched_data); > > struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh_state); > > DEFINE_PER_CPU(struct rcu_data, rcu_bh_data); > > > > +/* > > + * Ad-hoc diagnostic function, for use only after rcu_init() has > > + * returned. Assumes that the boot CPU is CPU 0. Assumes that > > + * the kernel has been built with CONFIG_TREE_RCU. Not for inclusion. > > + * Usage: "WARN_ON_ONCE(rcu_check_beenonline());" > > + */ > > +int rcu_check_beenonline(void) > > +{ > > + return !per_cpu(rcu_sched_data, 0).beenonline || > > + !per_cpu(rcu_bh_data, 0).beenonline; > > +} > > > > /* > > * Return true if an RCU grace period is in progress. The ACCESS_ONCE()s > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.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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