Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753767Ab0ADTay (ORCPT ); Mon, 4 Jan 2010 14:30:54 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753541Ab0ADTaw (ORCPT ); Mon, 4 Jan 2010 14:30:52 -0500 Received: from mx1.redhat.com ([209.132.183.28]:4478 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753513Ab0ADTaw (ORCPT ); Mon, 4 Jan 2010 14:30:52 -0500 Date: Mon, 4 Jan 2010 20:30:44 +0100 From: Oleg Nesterov To: Martin Schwidefsky Cc: caiqian@redhat.com, Heiko Carstens , Jan Kratochvil , Roland McGrath , linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, utrace-devel@redhat.com Subject: Re: s390 && user_enable_single_step() (Was: odd utrace testing results on s390x) Message-ID: <20100104193044.GB21146@redhat.com> References: <1503844142.2061111261478093776.JavaMail.root@zmail06.collab.prod.int.phx2.redhat.com> <1257887498.2061171261478252049.JavaMail.root@zmail06.collab.prod.int.phx2.redhat.com> <20100104155225.GA16650@redhat.com> <20100104171626.22ea2d9c@mschwide.boeblingen.de.ibm.com> <20100104181412.GA21146@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100104181412.GA21146@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1169 Lines: 36 On 01/04, Oleg Nesterov wrote: > > IOW. I think this problem is minor and probably can be ignored, Or may be not... Even if the child is not killed by SIGTRAP, it can get a lot of unnecessary traps. To verify, I did another trivial patch (below), and the test case from 6580807da14c423f0d0a708108e6df6ebc8bc83d does trigger a lot of "false step" printks. Hmm. And sometimes there is nothing in dmesg, but the test-case needs a lot of time to complete. "taskset -c" seems to always trigger printk's. Magic. Oleg. --- arch/s390/kernel/traps.c~ 2009-12-22 10:41:52.909174198 -0500 +++ arch/s390/kernel/traps.c 2010-01-04 13:19:51.038187586 -0500 @@ -384,6 +384,8 @@ void __kprobes do_single_step(struct pt_ } if (tracehook_consider_fatal_signal(current, SIGTRAP)) force_sig(SIGTRAP, current); + else + printk("false step\n"); } static void default_trap_handler(struct pt_regs * regs, long interruption_code) -- 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/