From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f182.google.com (mail-pd0-f182.google.com [209.85.192.182]) by kanga.kvack.org (Postfix) with ESMTP id 32C286B0075 for ; Tue, 4 Mar 2014 19:49:04 -0500 (EST) Received: by mail-pd0-f182.google.com with SMTP id g10so299256pdj.27 for ; Tue, 04 Mar 2014 16:49:03 -0800 (PST) Received: from mail-pd0-x22c.google.com (mail-pd0-x22c.google.com [2607:f8b0:400e:c02::22c]) by mx.google.com with ESMTPS id ub8si477956pac.329.2014.03.04.16.49.02 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 04 Mar 2014 16:49:03 -0800 (PST) Received: by mail-pd0-f172.google.com with SMTP id p10so295783pdj.31 for ; Tue, 04 Mar 2014 16:49:02 -0800 (PST) Message-ID: <1393980534.26794.147.camel@edumazet-glaptop2.roam.corp.google.com> Subject: Re: RCU stalls when running out of memory on 3.14-rc4 w/ NFS and kernel threads priorities changed From: Eric Dumazet Date: Tue, 04 Mar 2014 16:48:54 -0800 In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Florian Fainelli Cc: "linux-kernel@vger.kernel.org" , linux-mm , paulmck@linux.vnet.ibm.com, linux-nfs@vger.kernel.org, trond.myklebust@primarydata.com, netdev On Tue, 2014-03-04 at 15:55 -0800, Florian Fainelli wrote: > Hi all, > > I am seeing the following RCU stalls messages appearing on an ARMv7 > 4xCPUs system running 3.14-rc4: > > [ 42.974327] INFO: rcu_sched detected stalls on CPUs/tasks: > [ 42.979839] (detected by 0, t=2102 jiffies, g=4294967082, > c=4294967081, q=516) > [ 42.987169] INFO: Stall ended before state dump start > > this is happening under the following conditions: > > - the attached bumper.c binary alters various kernel thread priorities > based on the contents of bumpup.cfg and > - malloc_crazy is running from a NFS share > - malloc_crazy.c is running in a loop allocating chunks of memory but > never freeing it > > when the priorities are altered, instead of getting the OOM killer to > be invoked, the RCU stalls are happening. Taking NFS out of the > equation does not allow me to reproduce the problem even with the > priorities altered. > > This "problem" seems to have been there for quite a while now since I > was able to get 3.8.13 to trigger that bug as well, with a slightly > more detailed RCU debugging trace which points the finger at kswapd0. > > You should be able to get that reproduced under QEMU with the > Versatile Express platform emulating a Cortex A15 CPU and the attached > files. > > Any help or suggestions would be greatly appreciated. Thanks! Do you have a more complete trace, including stack traces ? -- 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/ . Don't email: email@kvack.org