From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752331AbcF1OIu (ORCPT ); Tue, 28 Jun 2016 10:08:50 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:40901 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752006AbcF1OIs (ORCPT ); Tue, 28 Jun 2016 10:08:48 -0400 X-IBM-Helo: d03dlp03.boulder.ibm.com X-IBM-MailFrom: aneesh.kumar@linux.vnet.ibm.com From: "Aneesh Kumar K.V" To: Michael Ellerman , Reza Arbab Cc: Benjamin Herrenschmidt , Paul Mackerras , Dan Williams , Balbir Singh , Gavin Shan , David Gibson , Vasant Hegde , Scott Wood , "Oliver O'Halloran" , Nathan Fontenot , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] powerpc/mm: update arch_{add,remove}_memory() for radix In-Reply-To: <1467112865.16036.4.camel@ellerman.id.au> References: <1466699962-22412-1-git-send-email-arbab@linux.vnet.ibm.com> <87mvmbygdb.fsf@skywalker.in.ibm.com> <20160623193739.GA19202@arbab-laptop.austin.ibm.com> <1467112865.16036.4.camel@ellerman.id.au> User-Agent: Notmuch/0.21 (https://notmuchmail.org) Emacs/24.5.1 (x86_64-pc-linux-gnu) Date: Tue, 28 Jun 2016 19:33:06 +0530 MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16062814-0020-0000-0000-0000093375DD X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16062814-0021-0000-0000-00005337686C Message-Id: <87ziq54did.fsf@skywalker.in.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-06-28_09:,, 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=8.0.1-1604210000 definitions=main-1606280130 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Michael Ellerman writes: > On Thu, 2016-06-23 at 14:37 -0500, Reza Arbab wrote: >> On Thu, Jun 23, 2016 at 10:47:20PM +0530, Aneesh Kumar K.V wrote: >> > Reza Arbab writes: >> > > These functions are making direct calls to the hash table APIs, >> > > leading to a BUG() on systems using radix. >> > > >> > > Switch them to the vmemmap_{create,remove}_mapping() wrappers, and >> > > move to the __meminit section. >> > >> > They are really not the same. They can possibly end up using different >> > base page size. Also vmemmap is available only with SPARSEMEM_VMEMMAP >> > enabled. Does hotplug depend on sparsemem vmemmap ? >> >> I'm not sure. Maybe it's best if I back up a step and explain what lead >> me to this patch. During hotplug, you get >> >> ... >> arch_add_memory >> create_section_mapping >> htab_bolt_mapping >> BUG_ON(!ppc_md.hpte_insert); >> >> So it seemed to me that I needed a radix equivalent of >> create_section_mapping(). >> >> After some digging, I found hash__vmemmap_create_mapping() and >> radix__vmemmap_create_mapping() did what I needed. I did not notice the >> #ifdef SPARSEMEM_VMEMMAP around them. > > I think that's more by luck than design. The vmemmap routines use > mmu_vmemmap_psize which is probably but not definitely the same as > mmu_linear_psize. > >> Could it be that the functions just need to be renamed >> hash__create_mapping()/radix__create_mapping() and moved out of #ifdef >> SPARSEMEM_VMEMMAP? > > No, you need to use mmu_linear_psize for the hotplug case. > > But you can probably factor out a common routine that both cases use, and hide > the hash vs radix check in that. > > And probably send me a patch to make MEMORY_HOTPLUG depend on !RADIX for v4.7? Few other stuff we need to still look from Radix point 1) machine check handling/memory errors 2) kexec -aneesh