Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752136AbbHMDzz (ORCPT ); Wed, 12 Aug 2015 23:55:55 -0400 Received: from mga03.intel.com ([134.134.136.65]:46990 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752063AbbHMDzu (ORCPT ); Wed, 12 Aug 2015 23:55:50 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.15,667,1432623600"; d="scan'208";a="767759975" Subject: [RFC PATCH 1/7] x86, mm: ZONE_DEVICE for "device memory" From: Dan Williams To: linux-kernel@vger.kernel.org Cc: boaz@plexistor.com, riel@redhat.com, linux-nvdimm@ml01.01.org, Dave Hansen , david@fromorbit.com, mingo@kernel.org, linux-mm@kvack.org, Ingo Molnar , mgorman@suse.de, "H. Peter Anvin" , ross.zwisler@linux.intel.com, torvalds@linux-foundation.org, hch@lst.de Date: Wed, 12 Aug 2015 23:50:05 -0400 Message-ID: <20150813035005.36913.77364.stgit@otcpl-skl-sds-2.jf.intel.com> In-Reply-To: <20150813031253.36913.29580.stgit@otcpl-skl-sds-2.jf.intel.com> References: <20150813031253.36913.29580.stgit@otcpl-skl-sds-2.jf.intel.com> User-Agent: StGit/0.17.1-8-g92dd MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6176 Lines: 196 While pmem is usable as a block device or via DAX mappings to userspace there are several usage scenarios that can not target pmem due to its lack of struct page coverage. In preparation for "hot plugging" pmem into the vmemmap add ZONE_DEVICE as a new zone to tag these pages separately from the ones that are subject to standard page allocations. Importantly "device memory" can be removed at will by userspace unbinding the driver of the device. Having a separate zone prevents allocation and otherwise marks these pages that are distinct from typical uniform memory. Device memory has different lifetime and performance characteristics than RAM. However, since we have run out of ZONES_SHIFT bits this functionality currently depends on sacrificing ZONE_DMA. arch_add_memory() is reorganized a bit in preparation for a new arch_add_dev_memory() api, for now there is no functional change to the memory hotplug code. Cc: H. Peter Anvin Cc: Ingo Molnar Cc: Dave Hansen Cc: Rik van Riel Cc: Mel Gorman Cc: linux-mm@kvack.org Signed-off-by: Dan Williams --- arch/x86/Kconfig | 13 +++++++++++++ arch/x86/mm/init_64.c | 32 +++++++++++++++++++++----------- include/linux/mmzone.h | 23 +++++++++++++++++++++++ mm/memory_hotplug.c | 5 ++++- mm/page_alloc.c | 3 +++ 5 files changed, 64 insertions(+), 12 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index b3a1a5d77d92..64829b17980b 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -308,6 +308,19 @@ config ZONE_DMA If unsure, say Y. +config ZONE_DEVICE + bool "Device memory (pmem, etc...) hotplug support" if EXPERT + default !ZONE_DMA + depends on !ZONE_DMA + help + Device memory hotplug support allows for establishing pmem, + or other device driver discovered memory regions, in the + memmap. This allows pfn_to_page() lookups of otherwise + "device-physical" addresses which is needed for using a DAX + mapping in an O_DIRECT operation, among other things. + + If FS_DAX is enabled, then say Y. + config SMP bool "Symmetric multi-processing support" ---help--- diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 3fba623e3ba5..94f0fa56f0ed 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -683,15 +683,8 @@ static void update_end_of_memory_vars(u64 start, u64 size) } } -/* - * Memory is added always to NORMAL zone. This means you will never get - * additional DMA/DMA32 memory. - */ -int arch_add_memory(int nid, u64 start, u64 size) +static int __arch_add_memory(int nid, u64 start, u64 size, struct zone *zone) { - struct pglist_data *pgdat = NODE_DATA(nid); - struct zone *zone = pgdat->node_zones + - zone_for_memory(nid, start, size, ZONE_NORMAL); unsigned long start_pfn = start >> PAGE_SHIFT; unsigned long nr_pages = size >> PAGE_SHIFT; int ret; @@ -701,11 +694,28 @@ int arch_add_memory(int nid, u64 start, u64 size) ret = __add_pages(nid, zone, start_pfn, nr_pages); WARN_ON_ONCE(ret); - /* update max_pfn, max_low_pfn and high_memory */ - update_end_of_memory_vars(start, size); + /* + * Update max_pfn, max_low_pfn and high_memory, unless we added + * "device memory" which should not effect max_pfn + */ + if (!is_dev_zone(zone)) + update_end_of_memory_vars(start, size); return ret; } + +/* + * Memory is added always to NORMAL zone. This means you will never get + * additional DMA/DMA32 memory. + */ +int arch_add_memory(int nid, u64 start, u64 size) +{ + struct pglist_data *pgdat = NODE_DATA(nid); + struct zone *zone = pgdat->node_zones + + zone_for_memory(nid, start, size, ZONE_NORMAL); + + return __arch_add_memory(nid, start, size, zone); +} EXPORT_SYMBOL_GPL(arch_add_memory); #define PAGE_INUSE 0xFD @@ -1028,7 +1038,7 @@ int __ref arch_remove_memory(u64 start, u64 size) return ret; } -#endif +#endif /* CONFIG_MEMORY_HOTREMOVE */ #endif /* CONFIG_MEMORY_HOTPLUG */ static struct kcore_list kcore_vsyscall; diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 754c25966a0a..9217fd93c25b 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -319,7 +319,11 @@ enum zone_type { ZONE_HIGHMEM, #endif ZONE_MOVABLE, +#ifdef CONFIG_ZONE_DEVICE + ZONE_DEVICE, +#endif __MAX_NR_ZONES + }; #ifndef __GENERATING_BOUNDS_H @@ -794,6 +798,25 @@ static inline bool pgdat_is_empty(pg_data_t *pgdat) return !pgdat->node_start_pfn && !pgdat->node_spanned_pages; } +static inline int zone_id(const struct zone *zone) +{ + struct pglist_data *pgdat = zone->zone_pgdat; + + return zone - pgdat->node_zones; +} + +#ifdef CONFIG_ZONE_DEVICE +static inline bool is_dev_zone(const struct zone *zone) +{ + return zone_id(zone) == ZONE_DEVICE; +} +#else +static inline bool is_dev_zone(const struct zone *zone) +{ + return false; +} +#endif + #include extern struct mutex zonelists_mutex; diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 26fbba7d888f..6bc5b755ce98 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -770,7 +770,10 @@ int __remove_pages(struct zone *zone, unsigned long phys_start_pfn, start = phys_start_pfn << PAGE_SHIFT; size = nr_pages * PAGE_SIZE; - ret = release_mem_region_adjustable(&iomem_resource, start, size); + + /* in the ZONE_DEVICE case device driver owns the memory region */ + if (!is_dev_zone(zone)) + ret = release_mem_region_adjustable(&iomem_resource, start, size); if (ret) { resource_size_t endres = start + size - 1; diff --git a/mm/page_alloc.c b/mm/page_alloc.c index ef19f22b2b7d..0f19b4e18233 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -207,6 +207,9 @@ static char * const zone_names[MAX_NR_ZONES] = { "HighMem", #endif "Movable", +#ifdef CONFIG_ZONE_DEVICE + "Device", +#endif }; int min_free_kbytes = 1024; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/