Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752001AbdIEIox (ORCPT ); Tue, 5 Sep 2017 04:44:53 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:47999 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750902AbdIEIos (ORCPT ); Tue, 5 Sep 2017 04:44:48 -0400 Subject: Re: [PATCH] mm, sparse: fix typo in online_mem_sections To: Michal Hocko , Anshuman Khandual References: <20170904112210.3401-1-mhocko@kernel.org> <4d648f70-325d-3f60-8620-94c232b380d8@linux.vnet.ibm.com> <20170905072836.i4dxrukevojty4ub@dhcp22.suse.cz> <20170905073730.4reirga47o4athse@dhcp22.suse.cz> Cc: Andrew Morton , Vlastimil Babka , linux-mm@kvack.org, LKML From: Anshuman Khandual Date: Tue, 5 Sep 2017 14:14:38 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: <20170905073730.4reirga47o4athse@dhcp22.suse.cz> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable x-cbid: 17090508-0016-0000-0000-000002621AB1 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17090508-0017-0000-0000-000006E4F6D6 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-09-05_03:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1707230000 definitions=main-1709050133 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1112 Lines: 24 On 09/05/2017 01:07 PM, Michal Hocko wrote: > On Tue 05-09-17 09:28:36, Michal Hocko wrote: >> On Tue 05-09-17 12:32:28, Anshuman Khandual wrote: >>> On 09/04/2017 04:52 PM, Michal Hocko wrote: >>>> From: Michal Hocko >>>> >>>> online_mem_sections accidentally marks online only the first section in >>>> the given range. This is a typo which hasn't been noticed because I >>>> haven't tested large 2GB blocks previously. All users of >>> >>> Section sizes are normally less than 2GB. Could you please elaborate >>> why this never got noticed before ? >> >> Section size is 128MB which is the default block size as well. So we >> have one section per block. But if the amount of memory is very large >> (64GB - see probe_memory_block_size) then we have a 2GB memory blocks >> so multiple sections per block. > > And just to clarify. Not that 64G would be too large but the original > patch has been merged in 4.13 so nobody probably managed to hit that > _yet_. Got it. Section size is 16MB and block size is 256MB on most of the POWER platforms. Hence this could have affected them as well.