From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sedat Dilek Subject: Re: 2.6.39-rc4+: Kernel leaking memory during FS scanning, regression? Date: Mon, 25 Apr 2011 20:13:27 +0200 Message-ID: References: <20110424202158.45578f31@neptune.home> <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> Reply-To: sedat.dilek@gmail.com Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: =?UTF-8?Q?Bruno_Pr=C3=A9mont?= , 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 To: paulmck@linux.vnet.ibm.com Return-path: In-Reply-To: <20110425172914.GB2468@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org 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=C3=A9mont wrote: >> On Mon, 25 April 2011 Linus Torvalds wrote: >> > 2011/4/25 Bruno Pr=C3=A9mont : >> > > >> > > 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 ten= ds >> > to overwhelm everything else - none of it looks unreasonable per s= e. >> > >> > 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 configurat= ion, >> > and seeing if that makes a difference: >> > >> > > Yes, it's uni-processor system, so SMP=3Dn. >> > > TINY_RCU=3Dy, PREEMPT_VOLUNTARY=3Dy (whole /proc/config.gz attac= hed 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-perform= ance >> > option". >> >> Well, TINY_RCU is the only option when doing PREEMPT_VOLUNTARY on >> SMP=3Dn... > > You can either set SMP=3Dy and NR_CPUS=3D1 or you can handed-edit > init/Kconfig to remove the dependency on SMP. =C2=A0Just change the > > =C2=A0 =C2=A0 =C2=A0 =C2=A0depends on !PREEMPT && SMP > > to: > > =C2=A0 =C2=A0 =C2=A0 =C2=A0depends 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 disab= led. >> >> > So right now I suspect that you have a situation where you just ha= ve a >> > simple load that just ends up never triggering any RCU cleanup, an= d >> > the tiny-rcu thing just keeps on gathering events and delays freei= ng >> > 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 compilin= g >> packages (and probably also just unpacking larger tarballs or runnin= g >> things like du). > > If it is broken, I will fix it. =C2=A0;-) > > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0= =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0Thanx, Paul > >> And with system doing nothing (except monitoring itself) memory usag= e >> 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=3D1130480 >> >> Attached graph matching numbers of previous mail. (dropping caches w= as 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 bein= g >> > too dang stupid" hypothesis. >> > >> > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0Linus > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdev= el" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at =C2=A0http://vger.kernel.org/majordomo-info.ht= ml > 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=3Dy CONFIG_X86_UP_IOAPIC=3Dy =2E..is not possible with CONFIG_SMP=3Dy 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=3Dy # CONFIG_TINY_RCU is not set # CONFIG_TINY_PREEMPT_RCU is not set CONFIG_PREEMPT_RCU=3Dy # CONFIG_RCU_TRACE is not set CONFIG_RCU_FANOUT=3D32 # CONFIG_RCU_FANOUT_EXACT is not set # CONFIG_TREE_RCU_TRACE is not set CONFIG_PREEMPT_NOTIFIERS=3Dy # CONFIG_SMP is not set # CONFIG_M486 is not set CONFIG_M686=3Dy CONFIG_NR_CPUS=3D1 # CONFIG_PREEMPT_NONE is not set # CONFIG_PREEMPT_VOLUNTARY is not set CONFIG_PREEMPT=3Dy CONFIG_X86_UP_APIC=3Dy CONFIG_X86_UP_IOAPIC=3Dy CONFIG_HIGHMEM4G=3Dy # CONFIG_HIGHMEM64G is not set CONFIG_HIGHMEM=3Dy CONFIG_DEBUG_PREEMPT=3Dy # 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: =2Econfig:2106:warning: override: TREE_PREEMPT_RCU changes choice state =2Econfig:2182:warning: override: PREEMPT changes choice state Not sure how to interprete them, so I am a bit careful :-). ( Untested - not compiled yet! ) - Sedat -