From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f198.google.com (mail-qk0-f198.google.com [209.85.220.198]) by kanga.kvack.org (Postfix) with ESMTP id F22276B0008 for ; Tue, 7 Aug 2018 10:55:01 -0400 (EDT) Received: by mail-qk0-f198.google.com with SMTP id 99-v6so16975988qkr.14 for ; Tue, 07 Aug 2018 07:55:01 -0700 (PDT) Received: from mx1.redhat.com (mx3-rdu2.redhat.com. [66.187.233.73]) by mx.google.com with ESMTPS id q65-v6si1430437qkd.337.2018.08.07.07.55.01 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 07 Aug 2018 07:55:01 -0700 (PDT) Subject: Re: [RFC PATCH 2/3] mm/memory_hotplug: Create __shrink_pages and move it to offline_pages References: <20180807133757.18352-1-osalvador@techadventures.net> <20180807133757.18352-3-osalvador@techadventures.net> <20180807135221.GA3301@redhat.com> From: David Hildenbrand Message-ID: Date: Tue, 7 Aug 2018 16:54:57 +0200 MIME-Version: 1.0 In-Reply-To: <20180807135221.GA3301@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: Jerome Glisse , osalvador@techadventures.net Cc: akpm@linux-foundation.org, mhocko@suse.com, dan.j.williams@intel.com, pasha.tatashin@oracle.com, yasu.isimatu@gmail.com, logang@deltatee.com, dave.jiang@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Oscar Salvador On 07.08.2018 15:52, Jerome Glisse wrote: > 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. I wonder if we could instead forward from the callers whether we are dealing with ZONE_DEVICE memory (is_device ...), at least that seems feasible in hmm code. Not having looked at details yet. > > Cheers, > JA(C)rA'me > -- Thanks, David / dhildenb