Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756868Ab1CaDo4 (ORCPT ); Wed, 30 Mar 2011 23:44:56 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:42141 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753905Ab1CaDoz convert rfc822-to-8bit (ORCPT ); Wed, 30 Mar 2011 23:44:55 -0400 MIME-Version: 1.0 In-Reply-To: <20110331033432.GA434@redhat.com> References: <20110329040939.GA32764@redhat.com> <20110331030917.GB26057@redhat.com> <20110331033432.GA434@redhat.com> From: Linus Torvalds Date: Wed, 30 Mar 2011 20:44:06 -0700 Message-ID: Subject: Re: excessive kworker activity when idle. (was Re: vma corruption in today's -git) To: Dave Jones , Andrew Morton , Linux Kernel , "Paul E. McKenney" Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1305 Lines: 27 On Wed, Mar 30, 2011 at 8:34 PM, Dave Jones wrote: > > so 'perf kmem record sleep 5' shows hundreds of calls kmem_cache_free from > the kworker processes. Called from shmem_i_callback, __d_free and file_free_rcu. > My guess is that my fuzzing caused so many allocations that the rcu freeing is > still ongoing an hour or so after the process has quit. ?does that make any sense? No, that shouldn't be the case. RCU freeing should go on for just a few RCU periods, and be done. I think there is some "limit the work we do for rcu each time" in order to not have bad latencies, but even so that shouldn't take _that_ long. And as you say, you should see the freeing in the slab stats. So clearly there are shmem inodes being destroyed, but it shouldn't be from an hour ago. I wonder if your system isn't as idle as you think it is. But I'm cc'ing Paul, maybe he'll disagree and say it's expected and that the RCU batch size is really small. Or at least give some hint about how to check the pending rcu state. Linus -- 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/