From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758077AbYDUArJ (ORCPT ); Sun, 20 Apr 2008 20:47:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751681AbYDUAq4 (ORCPT ); Sun, 20 Apr 2008 20:46:56 -0400 Received: from rv-out-0708.google.com ([209.85.198.243]:22552 "EHLO rv-out-0506.google.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751503AbYDUAqz (ORCPT ); Sun, 20 Apr 2008 20:46:55 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=awYggEqrCEoqVjtA3jH1YjggJxjne/6eEZrQTucHC4ji8yqhV4AmlgubjM2fmjG7YQpUf9Ga+o7PMGcIp0/g9UNVtJv6J2xKsO8Woq/R2gbEEWDmV9rPOqo78gaVb5paPtcSQ6cL0dvIeJKmubipLdIdFQB1JM6XrCrVN1WPTIc= Message-ID: Date: Sun, 20 Apr 2008 20:46:53 -0400 From: "Dan Upton" To: linux-kernel@vger.kernel.org Subject: Re: migration thread and active_load_balance In-Reply-To: <87tzhw8b1k.fsf@basil.nowhere.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <87tzhw8b1k.fsf@basil.nowhere.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > > > Anyway, like I said, I've spent several days trying to understand this > > error by putting in printk()s galore and doing traces through the > > That might be obvious, but are you aware that printks inside > the scheduler can lead to deadlocks? printk when the buffer > is full calls wake_up and that calls the scheduler. So for > debugging the scheduler you need some other way to get > the information out. > > -Andi > Yes, I've read that printk can cause deadlocks, although I get the deadlocks without printks as well. Also, I found a modification on kerneltrap (http://kerneltrap.org/mailarchive/linux-kernel/2008/1/23/595569) that seems to a decent job of preventing deadlocks due to printk, at least in my case (I see in the comments on that thread though that it's not perfect). -dan