From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751339AbaK2PVR (ORCPT ); Sat, 29 Nov 2014 10:21:17 -0500 Received: from mga03.intel.com ([134.134.136.65]:22636 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751033AbaK2PVP (ORCPT ); Sat, 29 Nov 2014 10:21:15 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.07,483,1413270000"; d="scan'208";a="645427328" Message-ID: <5479E467.5070701@linux.intel.com> Date: Sat, 29 Nov 2014 23:21:11 +0800 From: Jiang Liu Organization: Intel User-Agent: Mozilla/5.0 (Windows NT 6.2; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Borislav Petkov CC: linux-tip-commits@vger.kernel.org, matthias.bgg@gmail.com, tony.luck@intel.com, tglx@linutronix.de, benh@kernel.crashing.org, linux-kernel@vger.kernel.org, hpa@zytor.com, grant.likely@linaro.org, wangyijing@huawei.com, marc.zyngier@arm.com, bhelgaas@google.com, yingjoe.chen@mediatek.com, mingo@kernel.org Subject: Re: [tip:irq/irqdomain] irqdomain: Introduce helper function irq_domain_add_hierarchy() References: <1416061447-9472-5-git-send-email-jiang.liu@linux.intel.com> <20141129125319.GA6491@pd.tnic> <5479D84D.7000500@linux.intel.com> <20141129145616.GC5075@pd.tnic> In-Reply-To: <20141129145616.GC5075@pd.tnic> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2014/11/29 22:56, Borislav Petkov wrote: > On Sat, Nov 29, 2014 at 10:29:33PM +0800, Jiang Liu wrote: >> Thanks for reporting and fixing this. How about using GFP_ATOMIC >> here? > > Well, I don't see the need to use GFP_ATOMIC if we absolutely don't have > to. And in this case lockdep is, AFAICT, correct in saying that we still > can do allocations with interrupts disabled, only not go down into fs > and do all kinds of lock grabbing operations like page reclaim, writeout > or whatever it is being done nowadays there. > > Yeah, this is also some old "no-no" in my memory which says that we > should almost never use GFP_ATOMIC if it can be helped. Thanks for the info about GFP_ATOMIC, originally I have an impression that we should use GFP_ATOMIC when interrupt is disabled:( > > OTOH, I wonder if this code would rather need to hand down explicit gfp > flags in case it should be able to do GFP_ATOMIC operations at some > point... > > Thanks. >