From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f199.google.com (mail-qk0-f199.google.com [209.85.220.199]) by kanga.kvack.org (Postfix) with ESMTP id A76176B026A for ; Tue, 7 Aug 2018 09:52:27 -0400 (EDT) Received: by mail-qk0-f199.google.com with SMTP id q3-v6so16789565qki.4 for ; Tue, 07 Aug 2018 06:52:27 -0700 (PDT) Received: from mx1.redhat.com (mx3-rdu2.redhat.com. [66.187.233.73]) by mx.google.com with ESMTPS id p5-v6si1348058qkf.174.2018.08.07.06.52.26 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 07 Aug 2018 06:52:26 -0700 (PDT) Date: Tue, 7 Aug 2018 09:52:21 -0400 From: Jerome Glisse Subject: Re: [RFC PATCH 2/3] mm/memory_hotplug: Create __shrink_pages and move it to offline_pages Message-ID: <20180807135221.GA3301@redhat.com> References: <20180807133757.18352-1-osalvador@techadventures.net> <20180807133757.18352-3-osalvador@techadventures.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20180807133757.18352-3-osalvador@techadventures.net> Sender: owner-linux-mm@kvack.org List-ID: To: osalvador@techadventures.net Cc: akpm@linux-foundation.org, mhocko@suse.com, dan.j.williams@intel.com, pasha.tatashin@oracle.com, david@redhat.com, yasu.isimatu@gmail.com, logang@deltatee.com, dave.jiang@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Oscar Salvador On Tue, Aug 07, 2018 at 03:37:56PM +0200, osalvador@techadventures.net wrote: > From: Oscar Salvador [...] > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 9bd629944c91..e33555651e46 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c [...] > /** > * __remove_pages() - remove sections of pages from a zone > - * @zone: zone from which pages need to be removed > + * @nid: node which pages belong to > * @phys_start_pfn: starting pageframe (must be aligned to start of a section) > * @nr_pages: number of pages to remove (must be multiple of section size) > * @altmap: alternative device page map or %NULL if default memmap is used > @@ -548,7 +557,7 @@ static int __remove_section(struct zone *zone, struct mem_section *ms, > * sure that pages are marked reserved and zones are adjust properly by > * calling offline_pages(). > */ > -int __remove_pages(struct zone *zone, unsigned long phys_start_pfn, > +int __remove_pages(int nid, unsigned long phys_start_pfn, > unsigned long nr_pages, struct vmem_altmap *altmap) > { > unsigned long i; > @@ -556,10 +565,9 @@ int __remove_pages(struct zone *zone, unsigned long phys_start_pfn, > int sections_to_remove, ret = 0; > > /* In the ZONE_DEVICE case device driver owns the memory region */ > - if (is_dev_zone(zone)) { > - if (altmap) > - map_offset = vmem_altmap_offset(altmap); > - } else { > + if (altmap) > + map_offset = vmem_altmap_offset(altmap); > + else { This will break ZONE_DEVICE at least for HMM. While i think that altmap -> ZONE_DEVICE (ie altmap imply ZONE_DEVICE) the reverse is not true ie ZONE_DEVICE does not necessarily imply altmap. So with the above changes you change the expected behavior. You do need the zone to know if it is a ZONE_DEVICE. You could also lookup one of the struct page but my understanding is that this is what you want to avoid in the first place. Cheers, Jerome