From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753274AbeADVdM (ORCPT + 1 other); Thu, 4 Jan 2018 16:33:12 -0500 Received: from aserp2120.oracle.com ([141.146.126.78]:48280 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752666AbeADVdK (ORCPT ); Thu, 4 Jan 2018 16:33:10 -0500 Subject: Re: [PATCH 1/2] Move kfree_call_rcu() to slab_common.c From: Rao Shoaib To: Boqun Feng Cc: Matthew Wilcox , linux-kernel@vger.kernel.org, paulmck@linux.vnet.ibm.com, brouer@redhat.com, linux-mm@kvack.org References: <1514923898-2495-1-git-send-email-rao.shoaib@oracle.com> <20180102222341.GB20405@bombadil.infradead.org> <3be609d4-800e-a89e-f885-7e0f5d288862@oracle.com> <20180104013807.GA31392@tardis> Message-ID: <64ca3929-4044-9393-a6ca-70c0a2589a35@oracle.com> Date: Thu, 4 Jan 2018 13:27:49 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8764 signatures=668651 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=40 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1711220000 definitions=main-1801040293 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On 01/04/2018 12:35 PM, Rao Shoaib wrote: > Hi Boqun, > > Thanks a lot for all your guidance and for catching the cut and paster > error. Please see inline. > > > On 01/03/2018 05:38 PM, Boqun Feng wrote: >> >> But you introduced a bug here, you should use rcu_state_p instead of >> &rcu_sched_state as the third parameter for __call_rcu(). >> >> Please re-read: >> >>     https://marc.info/?l=linux-mm&m=151390529209639 >> >> , and there are other comments, which you still haven't resolved in this >> version. You may want to write a better commit log to explain the >> reasons of each modifcation and fix bugs or typos in your previous >> version. That's how review process works ;-) >> >> Regards, >> Boqun >> > This is definitely a serious error. Thanks for catching this. > > As far as your previous comments are concerned, only the following one > has not been addressed. Can you please elaborate as I do not > understand the comment. The code was expanded because the new macro > expansion check fails. Based on Matthew Wilcox's comment I have > reverted rcu_head_name back to rcu_head. It turns out I did not remember the real reason for the change. With the macro rewritten, using rcu_head as a macro argument does not work because it conflicts with the name of the type 'struct rcu_head' used in the macro. I have renamed the macro argument to rcu_name. Shoaib > >> +#define kfree_rcu(ptr, rcu_head_name) \ >> +    do { \ >> +        typeof(ptr) __ptr = ptr;    \ >> +        unsigned long __off = offsetof(typeof(*(__ptr)), \ >> +                              rcu_head_name); \ >> +        struct rcu_head *__rptr = (void *)__ptr + __off; \ >> +        __kfree_rcu(__rptr, __off); \ >> +    } while (0) > > why do you want to open code this? > > Does the following text for the commit log looks better. > > kfree_rcu() should use the new kfree_bulk() interface for freeing rcu > structures > > The newly implemented kfree_bulk() interfaces are more efficient, > using the interfaces for freeing rcu structures has shown performance > improvements in synthetic benchmarks that allocate and free rcu > structures at a high rate. > > Shoaib > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org.  For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: email@kvack.org