From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755308Ab1A1QzR (ORCPT ); Fri, 28 Jan 2011 11:55:17 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:47161 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755267Ab1A1QzQ (ORCPT ); Fri, 28 Jan 2011 11:55:16 -0500 Date: Fri, 28 Jan 2011 17:54:55 +0100 From: Ingo Molnar To: Tejun Heo Cc: roland@redhat.com, oleg@redhat.com, jan.kratochvil@redhat.com, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, Peter Zijlstra , Thomas Gleixner , =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker Subject: Re: [PATCHSET] ptrace,signal: group stop / ptrace updates Message-ID: <20110128165455.GA18194@elte.hu> References: <1296227324-25295-1-git-send-email-tj@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1296227324-25295-1-git-send-email-tj@kernel.org> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, I'm hijacking this thread, to report a signal handling bug that Linux and Bash has, and which has been there at least for 10 years since i started using SMP Linux systems ... It's not easy to reproduce but today i found a reproducer - maybe you guys have an idea what's going on. There's two very simple scripts, one calls the other in an infinite loop: $ cat test-signal #!/bin/bash while true; do ./test-signal2; done $ cat test-signal2 #!/bin/bash true The bug is that occasionally Ctrl-C does not get processed, and that the Ctrl-C is 'lost'. It can be reproduced here by running ./test-signal several times, and Ctrl-C-ing it: $ ./test-signal ^C $ ./test-signal ^C^C $ ./test-signal ^C See that '^C^C' line? That is where i had to do Ctrl-C twice. It only fails here about once every 10 times, so it's very rare. I have a stock F14 system running on that box, with the very latest .38 based kernel. Any ideas what's going on? Thanks, Ingo