From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755132Ab2LCQWi (ORCPT ); Mon, 3 Dec 2012 11:22:38 -0500 Received: from mx1.redhat.com ([209.132.183.28]:50995 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754293Ab2LCQWg (ORCPT ); Mon, 3 Dec 2012 11:22:36 -0500 From: Jeff Moyer To: Zach Brown Cc: Jens Axboe , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [patch] bdi: add a user-tunable cpu_list for the bdi flusher threads References: <20121130221542.GM18574@lenny.home.zabbo.net> X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 X-PCLoadLetter: What the f**k does that mean? Date: Mon, 03 Dec 2012 11:22:31 -0500 In-Reply-To: (Jeff Moyer's message of "Mon, 03 Dec 2012 10:49:25 -0500") Message-ID: User-Agent: Gnus/5.110011 (No Gnus v0.11) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Jeff Moyer writes: >>> + bdi->flusher_cpumask = kmalloc(sizeof(cpumask_t), GFP_KERNEL); >>> + if (!bdi->flusher_cpumask) >>> + return -ENOMEM; >> >> The bare GFP_KERNEL raises an eyebrow. Some bdi_init() callers like >> blk_alloc_queue_node() look like they'll want to pass in a gfp_t for the >> allocation. > > I'd be surprised if that was necessary, seeing how every single caller > of blk_alloc_queue_node passes in GFP_KERNEL. I'll make the change, > though, there aren't too many callers of bdi_init out there. No other callers of bdi_init want anything but GFP_KERNEL. In the case of blk_alloc_queue_node, even *it* doesn't honor the gfp_t passed in! Have a look at blkcg_init_queue (called from blk_alloc_queue_node) to see what I mean. Maybe that's a bug? I've written the patch to modify bdi_init to take a gfp_t, but I'm actually not in favor of this change, so I'm not going to post it (unless, of course, you can provide a compelling argument). :-) Cheers, Jeff