From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754123AbaE3Abq (ORCPT ); Thu, 29 May 2014 20:31:46 -0400 Received: from lgeamrelo04.lge.com ([156.147.1.127]:44542 "EHLO lgeamrelo04.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753712AbaE3Abp (ORCPT ); Thu, 29 May 2014 20:31:45 -0400 X-Original-SENDERIP: 10.177.220.169 X-Original-MAILFROM: minchan@kernel.org Date: Fri, 30 May 2014 09:32:19 +0900 From: Minchan Kim To: Dave Chinner Cc: Dave Jones , Linus Torvalds , Jens Axboe , Linux Kernel Mailing List , Andrew Morton , linux-mm , "H. Peter Anvin" , Ingo Molnar , Peter Zijlstra , Mel Gorman , Rik van Riel , Johannes Weiner , Hugh Dickins , Rusty Russell , "Michael S. Tsirkin" , Dave Hansen , Steven Rostedt Subject: Re: [RFC 2/2] x86_64: expand kernel stack to 16K Message-ID: <20140530003219.GN10092@bbox> References: <20140528223142.GO8554@dastard> <20140529013007.GF6677@dastard> <20140529072633.GH6677@dastard> <20140529235308.GA14410@dastard> <20140530000649.GA3477@redhat.com> <20140530002113.GC14410@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140530002113.GC14410@dastard> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 30, 2014 at 10:21:13AM +1000, Dave Chinner wrote: > On Thu, May 29, 2014 at 08:06:49PM -0400, Dave Jones wrote: > > On Fri, May 30, 2014 at 09:53:08AM +1000, Dave Chinner wrote: > > > > > That sounds like a plan. Perhaps it would be useful to add a > > > WARN_ON_ONCE(stack_usage > 8k) (or some other arbitrary depth beyond > > > 8k) so that we get some indication that we're hitting a deep stack > > > but the system otherwise keeps functioning. That gives us some > > > motivation to keep stack usage down but isn't a fatal problem like > > > it is now.... > > > > We have check_stack_usage() and DEBUG_STACK_USAGE for this. > > Though it needs some tweaking if we move to 16K > > Right, but it doesn't throw loud warnings when a specific threshold > is reached - it just issues a quiet message when a process exits > telling you what the maximum was without giving us a stack to chew > on.... But we could enhance the inform so notice the risk to the user. as follow ... "kworker/u24:1 (94) used greatest stack depth: 8K bytes left, it means there is some horrible stack hogger in your kernel. Please report it the LKML and enable stacktrace to investigate who is culprit" > > Cheers, > > Dave. > -- > Dave Chinner > david@fromorbit.com > > -- > 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 -- Kind regards, Minchan Kim