Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758820Ab1DYS2r (ORCPT ); Mon, 25 Apr 2011 14:28:47 -0400 Received: from e2.ny.us.ibm.com ([32.97.182.142]:35036 "EHLO e2.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758664Ab1DYS2p (ORCPT ); Mon, 25 Apr 2011 14:28:45 -0400 Date: Mon, 25 Apr 2011 11:28:40 -0700 From: "Paul E. McKenney" To: sedat.dilek@gmail.com Cc: Bruno =?iso-8859-1?Q?Pr=E9mont?= , Linus Torvalds , Mike Frysinger , KOSAKI Motohiro , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, "Paul E. McKenney" , Pekka Enberg Subject: Re: 2.6.39-rc4+: Kernel leaking memory during FS scanning, regression? Message-ID: <20110425182840.GK2468@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20110424235928.71af51e0@neptune.home> <20110425114429.266A.A69D9226@jp.fujitsu.com> <20110425111705.786ef0c5@neptune.home> <20110425180450.1ede0845@neptune.home> <20110425190032.7904c95d@neptune.home> <20110425172914.GB2468@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6025 Lines: 161 On Mon, Apr 25, 2011 at 08:13:27PM +0200, Sedat Dilek wrote: > On Mon, Apr 25, 2011 at 7:29 PM, Paul E. McKenney > wrote: > > On Mon, Apr 25, 2011 at 07:00:32PM +0200, Bruno Pr?mont wrote: > >> On Mon, 25 April 2011 Linus Torvalds wrote: > >> > 2011/4/25 Bruno Pr?mont : > >> > > > >> > > kmemleak reports 86681 new leaks between shortly after boot and -2 state. > >> > > (and 2348 additional ones between -2 and -4). > >> > > >> > I wouldn't necessarily trust kmemleak with the whole RCU-freeing > >> > thing. In your slubinfo reports, the kmemleak data itself also tends > >> > to overwhelm everything else - none of it looks unreasonable per se. > >> > > >> > That said, you clearly have a *lot* of filp entries. I wouldn't > >> > consider it unreasonable, though, because depending on load those may > >> > well be fine. Perhaps you really do have some application(s) that hold > >> > thousands of files open. The default file limit is 1024 (I think), but > >> > you can raise it, and some programs do end up opening tens of > >> > thousands of files for filesystem scanning purposes. > >> > > >> > That said, I would suggest simply trying a saner kernel configuration, > >> > and seeing if that makes a difference: > >> > > >> > > Yes, it's uni-processor system, so SMP=n. > >> > > TINY_RCU=y, PREEMPT_VOLUNTARY=y (whole /proc/config.gz attached keeping > >> > > compression) > >> > > >> > I'm not at all certain that TINY_RCU is appropriate for > >> > general-purpose loads. I'd call it more of a "embedded low-performance > >> > option". > >> > >> Well, TINY_RCU is the only option when doing PREEMPT_VOLUNTARY on > >> SMP=n... > > > > You can either set SMP=y and NR_CPUS=1 or you can handed-edit > > init/Kconfig to remove the dependency on SMP. ?Just change the > > > > ? ? ? ?depends on !PREEMPT && SMP > > > > to: > > > > ? ? ? ?depends on !PREEMPT > > > > This will work fine, especially for experimental purposes. > > > >> > The _real_ RCU implementation ("tree rcu") forces quiescent states > >> > every few jiffies and has logic to handle "I've got tons of RCU > >> > events, I really need to start handling them now". All of which I > >> > think tiny-rcu lacks. > >> > >> Going to try it out (will take some time to compile), kmemleak disabled. > >> > >> > So right now I suspect that you have a situation where you just have a > >> > simple load that just ends up never triggering any RCU cleanup, and > >> > the tiny-rcu thing just keeps on gathering events and delays freeing > >> > stuff almost arbitrarily long. > >> > >> I hope tiny-rcu is not that broken... as it would mean driving any > >> PREEMPT_NONE or PREEMPT_VOLUNTARY system out of memory when compiling > >> packages (and probably also just unpacking larger tarballs or running > >> things like du). > > > > If it is broken, I will fix it. ?;-) > > > > ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?Thanx, Paul > > > >> And with system doing nothing (except monitoring itself) memory usage > >> goes increasing all the time until it starves (well it seems to keep > >> ~20M free, pushing processes it can to swap). Config is just being > >> make oldconfig from working 2.6.38 kernel (answering default for new > >> options) > >> > >> Memory usage evolution graph in first message of this thread: > >> http://thread.gmane.org/gmane.linux.kernel.mm/61909/focus=1130480 > >> > >> Attached graph matching numbers of previous mail. (dropping caches was at > >> 17:55, system idle since then) > >> > >> Bruno > >> > >> > >> > So try CONFIG_PREEMPT and CONFIG_TREE_PREEMPT_RCU to see if the > >> > behavior goes away. That would confirm the "it's just tinyrcu being > >> > too dang stupid" hypothesis. > >> > > >> > ? ? ? ? ? ? ? ? ? ? ?Linus > > > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at ?http://vger.kernel.org/majordomo-info.html > > > > Hi, > > I was playing with Debian's kernel-buildsystem for -rc4 with a > self-defined '686-up' so-called flavour. > > Here I have a Banias Pentium-M (UP, *no* PAE) and still experimenting > with kernel-config options. > > CONFIG_X86_UP_APIC=y > CONFIG_X86_UP_IOAPIC=y > > ...is not possible with CONFIG_SMP=y Right, hence my advice to hand-edit init/Kconfig for experimental purposes. Once that is done, you can select CONFIG_TREE_RCU with CONFIG_SMP=n. Thanx, Paul > These settings are possible by not hacking existing Kconfigs: > > $ egrep 'M486|M686|X86_UP|CONFIG_SMP|NR_CPUS|PREEMPT|_RCU|_HIGHMEM|PAE' > debian/build/build_i386_none_686-up/.config > CONFIG_TREE_PREEMPT_RCU=y > # CONFIG_TINY_RCU is not set > # CONFIG_TINY_PREEMPT_RCU is not set > CONFIG_PREEMPT_RCU=y > # CONFIG_RCU_TRACE is not set > CONFIG_RCU_FANOUT=32 > # CONFIG_RCU_FANOUT_EXACT is not set > # CONFIG_TREE_RCU_TRACE is not set > CONFIG_PREEMPT_NOTIFIERS=y > # CONFIG_SMP is not set > # CONFIG_M486 is not set > CONFIG_M686=y > CONFIG_NR_CPUS=1 > # CONFIG_PREEMPT_NONE is not set > # CONFIG_PREEMPT_VOLUNTARY is not set > CONFIG_PREEMPT=y > CONFIG_X86_UP_APIC=y > CONFIG_X86_UP_IOAPIC=y > CONFIG_HIGHMEM4G=y > # CONFIG_HIGHMEM64G is not set > CONFIG_HIGHMEM=y > CONFIG_DEBUG_PREEMPT=y > # CONFIG_SPARSE_RCU_POINTER is not set > # CONFIG_DEBUG_HIGHMEM is not set > # CONFIG_RCU_TORTURE_TEST is not set > # CONFIG_RCU_CPU_STALL_DETECTOR is not set > # CONFIG_PREEMPT_TRACER is not set > > But I also see these warnings: > > .config:2106:warning: override: TREE_PREEMPT_RCU changes choice state > .config:2182:warning: override: PREEMPT changes choice state > > Not sure how to interprete them, so I am a bit careful :-). > > ( Untested - not compiled yet! ) > > - 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/