From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755226Ab0KKKeS (ORCPT ); Thu, 11 Nov 2010 05:34:18 -0500 Received: from one.firstfloor.org ([213.235.205.2]:47613 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754830Ab0KKKeR (ORCPT ); Thu, 11 Nov 2010 05:34:17 -0500 Date: Thu, 11 Nov 2010 11:34:15 +0100 From: Andi Kleen To: Jiri Olsa Cc: mingo@elte.hu, rostedt@goodmis.org, andi@firstfloor.org, lwoodman@redhat.com, hch@infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCHv2 1/2] tracing - fix recursive user stack trace Message-ID: <20101111103415.GD18718@basil.fritz.box> References: <20101110164413.GA5360@nowhere> <1289466549-7602-2-git-send-email-jolsa@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1289466549-7602-2-git-send-email-jolsa@redhat.com> 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 On Thu, Nov 11, 2010 at 10:09:08AM +0100, Jiri Olsa wrote: > The user stack trace can fault when examining the trace. Which > would call the do_page_fault handler, which would trace again, > which would do the user stack trace, which would fault and call > do_page_fault again ... > > Thus this is causing a recursive bug. We need to have a recursion > detector here. I suspect this problem is in more trace points: any NMI or MCE trace point or any other trace point that can be triggered from a page. so it seems to be a general bug fix independent of the other patch. -Andi