From 4c19087016e36a5f8d8be09ff1213ef7f8f57903 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Sun, 9 Aug 2015 15:29:06 -0400 Subject: [PATCH] mm: ZONE_DEVICE for "device memory" Orabug: 22913653 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. Cc: H. Peter Anvin Cc: Ingo Molnar Cc: Dave Hansen Cc: Rik van Riel Cc: Mel Gorman Cc: Jerome Glisse [hch: various simplifications in the arch interface] Signed-off-by: Christoph Hellwig Signed-off-by: Dan Williams Signed-off-by: Dan Duval (cherry picked from commit 033fbae988fcb67e5077203512181890848b8e90) Conflicts: include/linux/memory_hotplug.h mm/Kconfig --- arch/ia64/mm/init.c | 4 ++-- arch/powerpc/mm/mem.c | 4 ++-- arch/s390/mm/init.c | 2 +- arch/sh/mm/init.c | 5 +++-- arch/tile/mm/init.c | 2 +- arch/x86/mm/init_32.c | 4 ++-- arch/x86/mm/init_64.c | 4 ++-- include/linux/memory_hotplug.h | 5 +++-- include/linux/mmzone.h | 23 ++++++++++++++++++++++ mm/Kconfig | 35 ++++++++++++++++++++++++++++++++++ mm/memory_hotplug.c | 14 +++++++++++--- mm/page_alloc.c | 3 +++ 12 files changed, 88 insertions(+), 17 deletions(-) diff --git a/arch/ia64/mm/init.c b/arch/ia64/mm/init.c index a9b65cf7b34a..1c864a9dc8a6 100644 --- a/arch/ia64/mm/init.c +++ b/arch/ia64/mm/init.c @@ -652,7 +652,7 @@ mem_init (void) } #ifdef CONFIG_MEMORY_HOTPLUG -int arch_add_memory(int nid, u64 start, u64 size) +int arch_add_memory(int nid, u64 start, u64 size, bool for_device) { pg_data_t *pgdat; struct zone *zone; @@ -663,7 +663,7 @@ int arch_add_memory(int nid, u64 start, u64 size) pgdat = NODE_DATA(nid); zone = pgdat->node_zones + - zone_for_memory(nid, start, size, ZONE_NORMAL); + zone_for_memory(nid, start, size, ZONE_NORMAL, for_device); ret = __add_pages(nid, zone, start_pfn, nr_pages); if (ret) diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c index 45fda71feb27..43968d473f8d 100644 --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -113,7 +113,7 @@ int memory_add_physaddr_to_nid(u64 start) } #endif -int arch_add_memory(int nid, u64 start, u64 size) +int arch_add_memory(int nid, u64 start, u64 size, bool for_device) { struct pglist_data *pgdata; struct zone *zone; @@ -128,7 +128,7 @@ int arch_add_memory(int nid, u64 start, u64 size) /* this should work for most non-highmem platforms */ zone = pgdata->node_zones + - zone_for_memory(nid, start, size, 0); + zone_for_memory(nid, start, size, 0, for_device); return __add_pages(nid, zone, start_pfn, nr_pages); } diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c index 80875c43a4a4..087798144a14 100644 --- a/arch/s390/mm/init.c +++ b/arch/s390/mm/init.c @@ -168,7 +168,7 @@ void __init free_initrd_mem(unsigned long start, unsigned long end) #endif #ifdef CONFIG_MEMORY_HOTPLUG -int arch_add_memory(int nid, u64 start, u64 size) +int arch_add_memory(int nid, u64 start, u64 size, bool for_device) { unsigned long zone_start_pfn, zone_end_pfn, nr_pages; unsigned long start_pfn = PFN_DOWN(start); diff --git a/arch/sh/mm/init.c b/arch/sh/mm/init.c index 2790b6a64157..c1490096b863 100644 --- a/arch/sh/mm/init.c +++ b/arch/sh/mm/init.c @@ -485,7 +485,7 @@ void free_initrd_mem(unsigned long start, unsigned long end) #endif #ifdef CONFIG_MEMORY_HOTPLUG -int arch_add_memory(int nid, u64 start, u64 size) +int arch_add_memory(int nid, u64 start, u64 size, bool for_device) { pg_data_t *pgdat; unsigned long start_pfn = start >> PAGE_SHIFT; @@ -496,7 +496,8 @@ int arch_add_memory(int nid, u64 start, u64 size) /* We only have ZONE_NORMAL, so this is easy.. */ ret = __add_pages(nid, pgdat->node_zones + - zone_for_memory(nid, start, size, ZONE_NORMAL), + zone_for_memory(nid, start, size, ZONE_NORMAL, + for_device), start_pfn, nr_pages); if (unlikely(ret)) printk("%s: Failed, __add_pages() == %d\n", __func__, ret); diff --git a/arch/tile/mm/init.c b/arch/tile/mm/init.c index 5bd252e3fdc5..d4e1fc41d06d 100644 --- a/arch/tile/mm/init.c +++ b/arch/tile/mm/init.c @@ -863,7 +863,7 @@ void __init mem_init(void) * memory to the highmem for now. */ #ifndef CONFIG_NEED_MULTIPLE_NODES -int arch_add_memory(u64 start, u64 size) +int arch_add_memory(u64 start, u64 size, bool for_device) { struct pglist_data *pgdata = &contig_page_data; struct zone *zone = pgdata->node_zones + MAX_NR_ZONES-1; diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c index c23ab1ee3a9a..3c993d902b64 100644 --- a/arch/x86/mm/init_32.c +++ b/arch/x86/mm/init_32.c @@ -823,11 +823,11 @@ void __init mem_init(void) } #ifdef CONFIG_MEMORY_HOTPLUG -int arch_add_memory(int nid, u64 start, u64 size) +int arch_add_memory(int nid, u64 start, u64 size, bool for_device) { struct pglist_data *pgdata = NODE_DATA(nid); struct zone *zone = pgdata->node_zones + - zone_for_memory(nid, start, size, ZONE_HIGHMEM); + zone_for_memory(nid, start, size, ZONE_HIGHMEM, for_device); unsigned long start_pfn = start >> PAGE_SHIFT; unsigned long nr_pages = size >> PAGE_SHIFT; diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index f9977a7a9444..df48430c279b 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -687,11 +687,11 @@ 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) +int arch_add_memory(int nid, u64 start, u64 size, bool for_device) { struct pglist_data *pgdat = NODE_DATA(nid); struct zone *zone = pgdat->node_zones + - zone_for_memory(nid, start, size, ZONE_NORMAL); + zone_for_memory(nid, start, size, ZONE_NORMAL, for_device); unsigned long start_pfn = start >> PAGE_SHIFT; unsigned long nr_pages = size >> PAGE_SHIFT; int ret; diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h index 4caa65ca3177..62ff5bd7d276 100644 --- a/include/linux/memory_hotplug.h +++ b/include/linux/memory_hotplug.h @@ -267,9 +267,10 @@ static inline void remove_memory(int nid, u64 start, u64 size) {} extern int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn, void *arg, int (*func)(struct memory_block *, void *)); extern int add_memory(int nid, u64 start, u64 size); -extern int zone_for_memory(int nid, u64 start, u64 size, int zone_default); +extern int zone_for_memory(int nid, u64 start, u64 size, int zone_default, + bool for_device); extern int add_memory_resource(int nid, struct resource *resource); -extern int arch_add_memory(int nid, u64 start, u64 size); +extern int arch_add_memory(int nid, u64 start, u64 size, bool for_device); extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages); extern bool is_memblock_offlined(struct memory_block *mem); extern void remove_memory(int nid, u64 start, u64 size); diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 54d74f6eb233..ba700669d586 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 @@ -786,6 +790,25 @@ 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/Kconfig b/mm/Kconfig index 390214da4546..33f30121a7b9 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -635,3 +635,38 @@ config MAX_STACK_SIZE_MB changed to a smaller value in which case that is used. A sane initial value is 80 MB. + +# For architectures that support deferred memory initialisation +config ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT + bool + +config DEFERRED_STRUCT_PAGE_INIT + bool "Defer initialisation of struct pages to kswapd" + default n + depends on ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT + depends on MEMORY_HOTPLUG + help + Ordinarily all struct pages are initialised during early boot in a + single thread. On very large machines this can take a considerable + amount of time. If this option is set, large machines will bring up + a subset of memmap at boot and then initialise the rest in parallel + when kswapd starts. This has a potential performance impact on + processes running early in the lifetime of the systemm until kswapd + finishes the initialisation. + +config ZONE_DEVICE + bool "Device memory (pmem, etc...) hotplug support" if EXPERT + default !ZONE_DMA + depends on !ZONE_DMA + depends on MEMORY_HOTPLUG + depends on MEMORY_HOTREMOVE + depends on X86_64 #arch_add_memory() comprehends device memory + + 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. diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 74bfdcaeebab..31981dd7aa32 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -769,7 +769,10 @@ 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; @@ -1206,8 +1209,13 @@ static int should_add_memory_movable(int nid, u64 start, u64 size) return 0; } -int zone_for_memory(int nid, u64 start, u64 size, int zone_default) +int zone_for_memory(int nid, u64 start, u64 size, int zone_default, + bool for_device) { +#ifdef CONFIG_ZONE_DEVICE + if (for_device) + return ZONE_DEVICE; +#endif if (should_add_memory_movable(nid, start, size)) return ZONE_MOVABLE; @@ -1246,7 +1254,7 @@ int __ref add_memory_resource(int nid, struct resource *res) } /* call arch's memory hotadd */ - ret = arch_add_memory(nid, start, size); + ret = arch_add_memory(nid, start, size, false); if (ret < 0) goto error; diff --git a/mm/page_alloc.c b/mm/page_alloc.c index ab080bfeb5cd..f1de8e4de4b5 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -205,6 +205,9 @@ static char * const zone_names[MAX_NR_ZONES] = { "HighMem", #endif "Movable", +#ifdef CONFIG_ZONE_DEVICE + "Device", +#endif }; int min_free_kbytes = 1024; -- 2.50.1