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[62.201.165.239]) by smtp.gmail.com with ESMTPSA id 185-v6sm8025100wmy.38.2018.08.08.06.42.34 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 08 Aug 2018 06:42:35 -0700 (PDT) Received: by techadventures.net (Postfix, from userid 1000) id F1FB4124790; Wed, 8 Aug 2018 15:42:33 +0200 (CEST) Date: Wed, 8 Aug 2018 15:42:33 +0200 From: Oscar Salvador To: David Hildenbrand Cc: Jerome Glisse , akpm@linux-foundation.org, mhocko@suse.com, dan.j.williams@intel.com, yasu.isimatu@gmail.com, logang@deltatee.com, dave.jiang@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Oscar Salvador Subject: Re: [RFC PATCH 2/3] mm/memory_hotplug: Create __shrink_pages and move it to offline_pages Message-ID: <20180808134233.GA10946@techadventures.net> References: <20180807133757.18352-1-osalvador@techadventures.net> <20180807133757.18352-3-osalvador@techadventures.net> <20180807135221.GA3301@redhat.com> <20180807204834.GA6844@techadventures.net> <20180807221345.GD3301@redhat.com> <20180808073835.GA9568@techadventures.net> <44f74b58-aae0-a44c-3b98-7b1aac186f8e@redhat.com> <20180808075614.GB9568@techadventures.net> <7a64e67d-1df9-04ab-cc49-99a39aa90798@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7a64e67d-1df9-04ab-cc49-99a39aa90798@redhat.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 08, 2018 at 10:08:41AM +0200, David Hildenbrand wrote: > Then it is maybe time to cleary distinguish both types of memory, as > they are fundamentally different when it comes to online/offline behavior. > > Ordinary ram: > add_memory ... > online_pages ... > offline_pages > remove_memory > > Device memory > add_device_memory ... > remove_device_memory > > So adding/removing from the zone and stuff can be handled there. Uhm, I have been thinking about this. Maybe we could do something like (completely untested): == memory_hotplug code == int add_device_memory(int nid, unsigned long start, unsigned long size, struct vmem_altmap *altmap, bool mapping) { int ret; unsigned long start_pfn = PHYS_PFN(start); unsigned long nr_pages = size >> PAGE_SHIFT; mem_hotplug_begin(); if (mapping) ret = arch_add_memory(nid, start, size, altmap, false) else ret = add_pages(nid, start_pfn, nr_pages, altmap, false): if (!ret) { pgdata_t *pgdata = NODE_DATA(nid); struct zone *zone = pgdata->node_zones[ZONE_DEVICE]; online_mem_sections(start_pfn, start_pfn + nr_pages); move_pfn_range_to_zone(zone, start_pfn, nr_pages, altmap); } mem_hotplug_done(); return ret; } int del_device_memory(int nid, unsigned long start, unsigned long size, struct vmem_altmap *altmap, bool mapping) { int ret; unsigned long start_pfn = PHYS_PFN(start); unsigned long nr_pages = size >> PAGE_SHIFT; pgdata_t *pgdata = NODE_DATA(nid); struct zone *zone = pgdata->node_zones[ZONE_DEVICE]; mem_hotplug_begin(); offline_mem_sections(start_pfn, start_pfn + nr_pages); __shrink_pages(zone, start_pfn, start_pfn + nr_pages, nr_pages); if (mapping) ret = arch_remove_memory(nid, start, size, altmap) else ret = __remove_pages(nid, start_pfn, nr_pages, altmap) mem_hotplug_done(); return ret; } === And then, HMM/devm code could use it. For example: hmm_devmem_pages_create(): ... ... if (devmem->pagemap.type == MEMORY_DEVICE_PUBLIC) linear_mapping = true; else linear_mapping = false; ret = add_device_memory(nid, align_start, align_size, NULL, linear_mapping); if (ret) goto error_add_memory; ... ... hmm_devmem_release: ... ... if (resource->desc == IORES_DESC_DEVICE_PRIVATE_MEMORY) mapping = false; else mapping = true; del_device_memory(nid, start_pfn << PAGE_SHIFT, npages << PAGE_SHIFT, NULL, mapping); ... ... In this way, we do not need to play tricks in HMM/devm code, we just need to call those functions when adding/removing memory. We would still have to figure out a way to go for the release_mem_region_adjustable() stuff though. Thanks -- Oscar Salvador SUSE L3