From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756880AbZEPBTU (ORCPT ); Fri, 15 May 2009 21:19:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754193AbZEPBTG (ORCPT ); Fri, 15 May 2009 21:19:06 -0400 Received: from mga14.intel.com ([143.182.124.37]:31435 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753132AbZEPBTE (ORCPT ); Fri, 15 May 2009 21:19:04 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.41,202,1241420400"; d="scan'208";a="143448071" Subject: Re: [GIT PATCH] x86,percpu: fix pageattr handling with remap allocator From: Suresh Siddha Reply-To: suresh.b.siddha@intel.com To: Tejun Heo Cc: "JBeulich@novell.com" , "andi@firstfloor.org" , "mingo@elte.hu" , "linux-kernel-owner@vger.kernel.org" , "hpa@zytor.com" , "tglx@linutronix.de" , "linux-kernel@vger.kernel.org" In-Reply-To: <1242305390-21958-1-git-send-email-tj@kernel.org> References: <1242305390-21958-1-git-send-email-tj@kernel.org> Content-Type: text/plain Organization: Intel Corp Date: Fri, 15 May 2009 18:17:06 -0700 Message-Id: <1242436626.27006.8623.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.24.1 (2.24.1-2.fc10) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2009-05-14 at 05:49 -0700, Tejun Heo wrote: > Hello, > > Upon ack, please pull from the following git tree. > > git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc.git x86-percpu-pageattr > > This patchset fixes subtile bug in pageattr handling when remap percpu > first chunk allocator is in use and implements percpu_alloc kernel > parameter so that allocator can be selected from boot prompt. > > This problem was spotted by Jan Beulich. > > The remap allocator allocates a PMD page per cpu, returns whatever is > unnecessary to the page allocator and remaps the PMD page into vmalloc > area to construct the first percpu chunk. This is to take advantage > of large page mapping. Tejun, Can you please educate me why we need to map this first percpu chunk (which is pre-allocated during boot and is physically contiguous) into vmalloc area? Perhaps even for the other dynamically allocated secondary chunks? (as far as I can see, all the chunk allocations seems to be physically contiguous and later mapped into vmalloc area).. That should simplify these things quite a bit(atleast for first percpu chunk). I am missing something obvious I guess. thanks, suresh