From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752073AbdECPHH (ORCPT ); Wed, 3 May 2017 11:07:07 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:28431 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751046AbdECPG6 (ORCPT ); Wed, 3 May 2017 11:06:58 -0400 Subject: Re: [v2 3/5] mm: add "zero" argument to vmemmap allocators To: David Miller Cc: linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, borntraeger@de.ibm.com, heiko.carstens@de.ibm.com, willy@infradead.org References: <1490383192-981017-1-git-send-email-pasha.tatashin@oracle.com> <1490383192-981017-4-git-send-email-pasha.tatashin@oracle.com> <20170503.103428.1598887340082574002.davem@davemloft.net> From: Pasha Tatashin Message-ID: <3921e0c8-2c18-60e9-cc99-78dbed2dce90@oracle.com> Date: Wed, 3 May 2017 11:05:45 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.0 MIME-Version: 1.0 In-Reply-To: <20170503.103428.1598887340082574002.davem@davemloft.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Source-IP: aserv0022.oracle.com [141.146.126.234] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Dave, Thank you for the review. I will address your comment and update patchset.. Pasha On 05/03/2017 10:34 AM, David Miller wrote: > From: Pavel Tatashin > Date: Fri, 24 Mar 2017 15:19:50 -0400 > >> Allow clients to request non-zeroed memory from vmemmap allocator. >> The following two public function have a new boolean argument called zero: >> >> __vmemmap_alloc_block_buf() >> vmemmap_alloc_block() >> >> When zero is true, memory that is allocated by memblock allocator is zeroed >> (the current behavior), when argument is false, the memory is not zeroed. >> >> This change allows for optimizations where client knows when it is better >> to zero memory: may be later when other CPUs are started, or may be client >> is going to set every byte in the allocated memory, so no need to zero >> memory beforehand. >> >> Signed-off-by: Pavel Tatashin >> Reviewed-by: Shannon Nelson > > I think when you add a new argument that can adjust behavior, you > should add the new argument but retain exactly the current behavior in > the existing calls. > > Then later you can piece by piece change behavior, and document properly > in the commit message what is happening and why the transformation is > legal. > > Here, you are adding the new boolean to __earlyonly_bootmem_alloc() and > then making sparse_mem_maps_populate_node() pass false, which changes > behavior such that it doesn't get zero'd memory any more. > > Please make one change at a time. Otherwise review and bisection is > going to be difficult. > > -- > To unsubscribe from this list: send the line "unsubscribe sparclinux" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >