From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755282Ab3EaROn (ORCPT ); Fri, 31 May 2013 13:14:43 -0400 Received: from mx1.redhat.com ([209.132.183.28]:50685 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751311Ab3EaROe (ORCPT ); Fri, 31 May 2013 13:14:34 -0400 Date: Fri, 31 May 2013 19:10:25 +0200 From: Oleg Nesterov To: Andrew Morton Cc: Al Viro , Guy Streeter , Eric Paris , David Woodhouse , linux-kernel@vger.kernel.org Subject: Re: [PATCH] audit: wait_for_auditd() should use TASK_UNINTERRUPTIBLE Message-ID: <20130531171025.GA32387@redhat.com> References: <20130524173925.GA17177@redhat.com> <20130529145933.6e02f8379cf20b9c7ef30977@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130529145933.6e02f8379cf20b9c7ef30977@linux-foundation.org> 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 On 05/29, Andrew Morton wrote: > > On Fri, 24 May 2013 19:39:25 +0200 Oleg Nesterov wrote: > > > audit_log_start() does wait_for_auditd() in a loop until > > audit_backlog_wait_time passes or audit_skb_queue has a room. > > > > If signal_pending() is true this becomes a busy-wait loop, > > schedule() in TASK_INTERRUPTIBLE won't block. > > And that's game over for a uniprocessor non-preempt machine, yes? If this task is rt, yes. Otherwise schedule() still does pick_next_task() but this is obviously bad anyway. So I fully agree with "Cc: stable" you added. > > Reported-by: Guy Streeter > > And what did Guy report? "that looks screwy"? "my machine locked up"? He also investigated the problem and provided the detailed explanation ;) Oleg.