From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f71.google.com (mail-pl0-f71.google.com [209.85.160.71]) by kanga.kvack.org (Postfix) with ESMTP id 908D56B0003 for ; Wed, 18 Jul 2018 16:16:32 -0400 (EDT) Received: by mail-pl0-f71.google.com with SMTP id g15-v6so3111496plo.11 for ; Wed, 18 Jul 2018 13:16:32 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id y10-v6sor1055093pga.170.2018.07.18.13.16.30 for (Google Transport Security); Wed, 18 Jul 2018 13:16:30 -0700 (PDT) Date: Wed, 18 Jul 2018 13:16:28 -0700 (PDT) From: David Rientjes Subject: Re: [PATCH] mm/page_alloc: Deprecate kernelcore=nn and movable_core= In-Reply-To: <20180717233100.GH1724@MiWiFi-R3L-srv> Message-ID: References: <20180717131837.18411-1-bhe@redhat.com> <20180717233100.GH1724@MiWiFi-R3L-srv> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Baoquan He Cc: mhocko@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, corbet@lwn.net, linux-doc@vger.kernel.org On Wed, 18 Jul 2018, Baoquan He wrote: > > > We can still use 'kernelcore=mirror' or 'movable_node' for the usage > > > of hotplug and movable zone. If somebody shows up with a valid usecase > > > we can reconsider. > > > > > > > We actively use kernelcore=n%, I had recently added support for the option > > in the first place in 4.17. It's certainly not deprecated. > > Thanks for telling. Just for curiosity, could you tell the scenario you > are using kernelcore=n%? Since it evenly spread movable area on nodes, > we may not be able to physically hot unplug/plug RAM. > To evenly distribute ZONE_MOVABLE over a set of nodes regardless of the many memory capacities of systems that we have where individual command lines cannot be tuned. But you want to deprecate kernelcore=nn, not just the percent version, so I assume that's not the answer you're looking for. We do not enable CONFIG_MEMORY_HOTPLUG so this deprecation would break our userspace such that we cannot use ZONE_MOVABLE.