From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: Re: 2.6.39-rc4+: Kernel leaking memory during FS scanning, regression? Date: Wed, 27 Apr 2011 14:55:49 -0700 Message-ID: <20110427215549.GN2135@linux.vnet.ibm.com> References: <20110425191607.GL2468@linux.vnet.ibm.com> <20110425231016.34b4293e@neptune.home> <20110425214933.GO2468@linux.vnet.ibm.com> <20110426081904.0d2b1494@pluto.restena.lu> <20110426112756.GF4308@linux.vnet.ibm.com> <20110426183859.6ff6279b@neptune.home> <20110426190918.01660ccf@neptune.home> Reply-To: paulmck@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Cc: Linus Torvalds , Bruno =?iso-8859-1?Q?Pr=E9mont?= , Ingo Molnar , Peter Zijlstra , Mike Frysinger , KOSAKI Motohiro , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, "Paul E. McKenney" , Pekka Enberg To: Thomas Gleixner Return-path: Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Wed, Apr 27, 2011 at 12:28:37AM +0200, Thomas Gleixner wrote: > On Tue, 26 Apr 2011, Linus Torvalds wrote: >=20 > > On Tue, Apr 26, 2011 at 10:09 AM, Bruno Pr=E9mont > > wrote: > > > > > > Just in case, /proc/$(pidof rcu_kthread)/status shows ~20k voluntar= y > > > context switches and exactly one non-voluntary one. > > > > > > In addition when rcu_kthread has stopped doing its work > > > `swapoff $(swapdevice)` seems to block forever (at least normal shu= tdown > > > blocks on disabling swap device). > > > If I get to do it when I get back home I will manually try to swapo= ff > > > and take process traces with sysrq-t. > >=20 > > That "exactly one non-voluntary one" sounds like the smoking gun. > >=20 > > Normally SCHED_FIFO runs until it voluntarily gives up the CPU. That'= s > > kind of the point of SCHED_FIFO. Involuntary context switches happen > > when some higher-priority SCHED_FIFO process becomes runnable (irq > > handlers? You _do_ have CONFIG_IRQ_FORCED_THREADING=3Dy in your confi= g > > too), and maybe there is a bug in the runqueue handling for that case= . >=20 > The forced irq threading is only effective when you add the command > line parameter "threadirqs". I don't see any irq threads in the ps > outputs, so that's not the problem. >=20 > Though the whole ps output is weird. There is only one thread/process > which accumulated CPU time >=20 > collectd 1605 0.6 0.7 49924 3748 ? SNLsl 22:14 0:14 I believe that the above is the script that prints out the RCU debugfs information periodically. Unless there is something else that begins with "collectd" instead of just collectdebugfs.sh. Thanx, Paul > All others show 0:00 CPU time - not only kthread_rcu. >=20 > Bruno, are you running on real hardware or in a virtual machine? >=20 > Can you please enable CONFIG_SCHED_DEBUG and provide the output of > /proc/sched_stat when the problem surfaces and a minute after the > first snapshot? >=20 > Also please apply the patch below and check, whether the printk shows > up in your dmesg. >=20 > Thanks, >=20 > tglx >=20 > --- > kernel/sched_rt.c | 1 + > 1 file changed, 1 insertion(+) >=20 > Index: linux-2.6-tip/kernel/sched_rt.c > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > --- linux-2.6-tip.orig/kernel/sched_rt.c > +++ linux-2.6-tip/kernel/sched_rt.c > @@ -609,6 +609,7 @@ static int sched_rt_runtime_exceeded(str >=20 > if (rt_rq->rt_time > runtime) { > rt_rq->rt_throttled =3D 1; > + printk_once(KERN_WARNING "sched: RT throttling activated\n"); > if (rt_rq_throttled(rt_rq)) { > sched_rt_rq_dequeue(rt_rq); > return 1; -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter= .ca/ Don't email: email@kvack.org