From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759367Ab1LPN1H (ORCPT ); Fri, 16 Dec 2011 08:27:07 -0500 Received: from casper.infradead.org ([85.118.1.10]:34487 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756407Ab1LPN06 convert rfc822-to-8bit (ORCPT ); Fri, 16 Dec 2011 08:26:58 -0500 Message-ID: <1324041955.18942.97.camel@twins> Subject: Re: printk() vs tty_io From: Peter Zijlstra To: Linus Torvalds Cc: "Ted Ts'o" , Alan Cox , Greg KH , linux-kernel , Ingo Molnar Date: Fri, 16 Dec 2011 14:25:55 +0100 In-Reply-To: References: <1323804803.9082.40.camel@twins> <20111214104308.14d0500c@pyramind.ukuu.org.uk> <1323860206.28489.35.camel@twins> <20111214140527.GA18080@thunk.org> <1323872631.28489.37.camel@twins> <1323943005.18942.18.camel@twins> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT X-Mailer: Evolution 3.2.1- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2011-12-15 at 09:08 -0800, Linus Torvalds wrote: > Peter, why do you want to try to work from under the rq lock? As Ingo already mentioned, there was no strong reason. The rationale was reducing surprise lockups like that xtime_lock thing. Also, there are various WARNs in the scheduler code that could possibly trigger and cause a deadlock. Then again, they're not supposed to trigger and mostly if they do we don't get an insta deadlock (at least not on the consoles I've used), but there is the possibility of course. I'm not sure the WARNs are enough reason to invent a new async printk facility, but if you feel strongly about that I can look into doing it.