Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755210Ab1DZMu2 (ORCPT ); Tue, 26 Apr 2011 08:50:28 -0400 Received: from mail-qw0-f46.google.com ([209.85.216.46]:62851 "EHLO mail-qw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753200Ab1DZMu0 convert rfc822-to-8bit (ORCPT ); Tue, 26 Apr 2011 08:50:26 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=mime-version:reply-to:in-reply-to:references:date:message-id :subject:from:to:cc:content-type:content-transfer-encoding; b=givVzzB98LP2LMk9ArP7Xufz4GDU/RtffFACsfCAgXbXWv7Y5tFZ8JgjoEDo90NYrO Low6Em20smgbOoy/h4zhQO5hSqQVV6xDtjmR7XefRcDRHkrlxu2hlzADlBMcvyBE/Sc8 sw/SKl8MbcYSOt12C053OZHrM+esquUP41aOA= MIME-Version: 1.0 Reply-To: sedat.dilek@gmail.com In-Reply-To: <20110426124256.GI4308@linux.vnet.ibm.com> References: <20110423210539.GI2628@linux.vnet.ibm.com> <20110424062728.GM2628@linux.vnet.ibm.com> <20110424164331.GN2628@linux.vnet.ibm.com> <20110426050612.GA7651@linux.vnet.ibm.com> <20110426124256.GI4308@linux.vnet.ibm.com> Date: Tue, 26 Apr 2011 14:50:25 +0200 Message-ID: Subject: Re: linux-next: Tree for April 14 (Call-traces: RCU/ACPI/WQ related?) From: Sedat Dilek To: paulmck@linux.vnet.ibm.com Cc: Stephen Rothwell , linux-next@vger.kernel.org, LKML , peterz@infradead.org Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8266 Lines: 198 On Tue, Apr 26, 2011 at 2:42 PM, Paul E. McKenney wrote: > On Tue, Apr 26, 2011 at 01:45:31PM +0200, Sedat Dilek wrote: >> On Tue, Apr 26, 2011 at 7:06 AM, Paul E. McKenney >> wrote: >> > On Sun, Apr 24, 2011 at 09:43:31AM -0700, Paul E. McKenney wrote: >> >> On Sun, Apr 24, 2011 at 11:36:44AM +0200, Sedat Dilek wrote: >> >> > On Sun, Apr 24, 2011 at 8:27 AM, Paul E. McKenney >> >> > wrote: >> >> >> >> [ . . . ] >> >> >> >> > > OK, this looks unrelated, but just in case, could you please try it >> >> > > again with the following patch?  (Not mainlinable, debug only.) >> >> > > >> >> > > Also, it does look like you are still seeing a grace-period hang. >> >> > > Could you please send the output of the script?  Same one as last time. >> >> > > >> >> > >                                                        Thanx, Paul >> >> > > >> >> > > ------------------------------------------------------------------------ >> >> > > >> >> > >  debugobjects.c |    8 +++++--- >> >> > >  1 file changed, 5 insertions(+), 3 deletions(-) >> >> > > >> >> > > diff --git a/lib/debugobjects.c b/lib/debugobjects.c >> >> > > index 9d86e45..10a7c7a 100644 >> >> > > --- a/lib/debugobjects.c >> >> > > +++ b/lib/debugobjects.c >> >> > > @@ -289,10 +289,12 @@ static void debug_object_is_on_stack(void *addr, int onstack) >> >> > >                return; >> >> > > >> >> > >        limit++; >> >> > > -       if (is_on_stack) >> >> > > +       if (is_on_stack) { >> >> > > +               struct rcu_head *p = (struct rcu_head *)addr; >> >> > >                printk(KERN_WARNING >> >> > > -                      "ODEBUG: object is on stack, but not annotated\n"); >> >> > > -       else >> >> > > +                      "ODEBUG: object is on stack, but not annotated: %p\n", >> >> > > +                      p->func); >> >> > > +       } else >> >> > >                printk(KERN_WARNING >> >> > >                       "ODEBUG: object is not on stack, but annotated\n"); >> >> > >        WARN_ON(1); >> >> > > >> >> > >> >> > Somehow your attached patch was not applicable. >> >> > As the changes were a few lines I applied it by myself. >> >> > Attached are log, dmesg and patches (orig + mine) >> >> >> >> Hmmm...  Does 0xc10231a1 correspond to a function in your build?  If so, >> >> could you please let me know which one? >> >> >> >> OK, so according to "ps" the per-CPU kthread is runnable, but it appears >> >> to never run.  You only have one CPU, so it cannot be waiting due to >> >> running on the wrong CPU.  The only other loop is in wait_event(), and >> >> that code looks good -- besides, if wait_event() was broken, we would >> >> be seeing breakage everywhere. >> >> >> >> Peter, any thoughts on what I might have done wrong to get the scheduler >> >> into a state where it was ignoring a runnable realtime task? >> > >> > Hello, Sedat, >> > >> > Here is a diagnostic patch to apply on top of sedat.2011.04.23a from >> > the -rcu git tree.  Could you please try it out, let me know what >> > happens, and run the last collectdebugfs.sh during the test? >> > >> >                                                        Thanx, Paul >> > >> > ------------------------------------------------------------------------ >> > >> > diff --git a/kernel/rcutree.c b/kernel/rcutree.c >> > index 6cf6e47..65ae701 100644 >> > --- a/kernel/rcutree.c >> > +++ b/kernel/rcutree.c >> > @@ -1524,9 +1524,9 @@ static void rcu_cpu_kthread_setrt(int cpu, int to_rt) >> >                return; >> >        if (to_rt) { >> >                policy = SCHED_NORMAL; >> > -               sp.sched_priority = RCU_KTHREAD_PRIO; >> > +               sp.sched_priority = 0; >> >        } else { >> > -               policy = SCHED_FIFO; >> > +               policy = SCHED_NORMAL; >> >                sp.sched_priority = 0; >> >        } >> >        sched_setscheduler_nocheck(t, policy, &sp); >> > @@ -1566,8 +1566,8 @@ static void rcu_yield(void (*f)(unsigned long), unsigned long arg) >> >        sp.sched_priority = 0; >> >        sched_setscheduler_nocheck(current, SCHED_NORMAL, &sp); >> >        schedule(); >> > -       sp.sched_priority = RCU_KTHREAD_PRIO; >> > -       sched_setscheduler_nocheck(current, SCHED_FIFO, &sp); >> > +       sp.sched_priority = 0; >> > +       sched_setscheduler_nocheck(current, SCHED_NORMAL, &sp); >> >        del_timer(&yield_timer); >> >  } >> > >> > @@ -1671,8 +1671,8 @@ static int __cpuinit rcu_spawn_one_cpu_kthread(int cpu) >> >        WARN_ON_ONCE(per_cpu(rcu_cpu_kthread_task, cpu) != NULL); >> >        per_cpu(rcu_cpu_kthread_task, cpu) = t; >> >        wake_up_process(t); >> > -       sp.sched_priority = RCU_KTHREAD_PRIO; >> > -       sched_setscheduler_nocheck(t, SCHED_FIFO, &sp); >> > +       sp.sched_priority = 0; >> > +       sched_setscheduler_nocheck(t, SCHED_NORMAL, &sp); >> >        return 0; >> >  } >> > >> > @@ -1713,8 +1713,8 @@ static int rcu_node_kthread(void *arg) >> >                                continue; >> >                        } >> >                        per_cpu(rcu_cpu_has_work, cpu) = 1; >> > -                       sp.sched_priority = RCU_KTHREAD_PRIO; >> > -                       sched_setscheduler_nocheck(t, SCHED_FIFO, &sp); >> > +                       sp.sched_priority = 0; >> > +                       sched_setscheduler_nocheck(t, SCHED_NORMAL, &sp); >> >                        preempt_enable(); >> >                } >> >        } >> > diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h >> > index a21413d..baee185 100644 >> > --- a/kernel/rcutree_plugin.h >> > +++ b/kernel/rcutree_plugin.h >> > @@ -1307,8 +1307,8 @@ static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp, >> >        rnp->boost_kthread_task = t; >> >        raw_spin_unlock_irqrestore(&rnp->lock, flags); >> >        wake_up_process(t); >> > -       sp.sched_priority = RCU_KTHREAD_PRIO; >> > -       sched_setscheduler_nocheck(t, SCHED_FIFO, &sp); >> > +       sp.sched_priority = 0; >> > +       sched_setscheduler_nocheck(t, SCHED_NORMAL, &sp); >> >        return 0; >> >  } >> > >> > >> >> Hi Paul, >> >> I have tested with your patch and kept the kernel-config file from >> previous tests (don't get confused by the new name). >> Hope this helps you. >> >> I have some questions to k-c options espcially X86_UP and >> CONFIG_RCU_FANOUT=32 options. >> To what extent can they influence our RCU issue? >> The below options were not set for this round of testing, but I would >> like to have a feedback. >> Thanks in advance. >> >> Would these settings be more optimal for a UP-machine? >> >> # CONFIG_SMP is not set >> # CONFIG_M486 is not set >> CONFIG_M686=y >> CONFIG_NR_CPUS=1 > > These should be fine. > >> CONFIG_X86_UP_APIC=y >> CONFIG_X86_UP_IOAPIC=y > > These I don't know about. > >> CONFIG_HIGHMEM4G=y > > This one seems good for allowing the system to go as long as possible. > >> Is CONFIG_RCU_FANOUT=32 OK? > > On a UP system, this one doesn't matter. > >> With reverting commit 687d7a960aea46e016182c7ce346d62c4dbd0366 ("rcu: >> restrict TREE_RCU to SMP builds with !PREEMPT"). > > Thank you for trying this one out! > > I don't see any sign of a grace-period hang.  Did your test complete > correctly? > >                                                        Thanx, Paul > Thanks for the comments. I let run the script very long (approx. one hour) and did parallelly my daily work. Then booted into a known as working kernel. Did I miss something, should I stress more? - Sedat - -- 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/