From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964988AbWLTLCK (ORCPT ); Wed, 20 Dec 2006 06:02:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964991AbWLTLCK (ORCPT ); Wed, 20 Dec 2006 06:02:10 -0500 Received: from smtp.osdl.org ([65.172.181.25]:54739 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964988AbWLTLCJ (ORCPT ); Wed, 20 Dec 2006 06:02:09 -0500 Date: Wed, 20 Dec 2006 03:02:04 -0800 From: Andrew Morton To: Arjan van de Ven Cc: linux-kernel@vger.kernel.org Subject: Re: + down_write-preserve-local-irqs.patch added to -mm tree Message-Id: <20061220030204.d070c807.akpm@osdl.org> In-Reply-To: <1166612063.3365.1367.camel@laptopd505.fenrus.org> References: <200612201038.kBKAcN4L026466@shell0.pdx.osdl.net> <1166612063.3365.1367.camel@laptopd505.fenrus.org> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.17; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 20 Dec 2006 11:54:23 +0100 Arjan van de Ven wrote: > On Wed, 2006-12-20 at 02:38 -0800, akpm@osdl.org wrote: > > The patch titled > > down_write(): preserve local irqs > > has been added to the -mm tree. Its filename is > > down_write-preserve-local-irqs.patch > > > > See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find > > out what to do about this > > > > ------------------------------------------------------ > > Subject: down_write(): preserve local irqs > > excuse me? Am I missing something here? Lots. > down_write() is a sleeping function, right? what business does it have > to be *ever* called with irqs off? > > if the answer is "none whatsoever", what good is saving irq state then? > a) this patch is for testers to confirm that this fixes the hangs b) there's plenty of precendent for this - powerpc won't boot if mutex_lock() enables interrupts, for example. We just assume that during early boot these sleeping locks aren't contended. yes, it does suck.