From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f72.google.com (mail-wm0-f72.google.com [74.125.82.72]) by kanga.kvack.org (Postfix) with ESMTP id EA2986B02FA for ; Wed, 26 Jul 2017 04:33:54 -0400 (EDT) Received: by mail-wm0-f72.google.com with SMTP id m80so4905066wmd.4 for ; Wed, 26 Jul 2017 01:33:54 -0700 (PDT) Received: from mail-wr0-f196.google.com (mail-wr0-f196.google.com. [209.85.128.196]) by mx.google.com with ESMTPS id i6si12872946wrc.340.2017.07.26.01.33.53 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 26 Jul 2017 01:33:53 -0700 (PDT) Received: by mail-wr0-f196.google.com with SMTP id g32so4307124wrd.5 for ; Wed, 26 Jul 2017 01:33:53 -0700 (PDT) From: Michal Hocko Subject: [RFC PATCH 3/5] mm, memory_hotplug: allocate memmap from the added memory range for sparse-vmemmap Date: Wed, 26 Jul 2017 10:33:31 +0200 Message-Id: <20170726083333.17754-4-mhocko@kernel.org> In-Reply-To: <20170726083333.17754-1-mhocko@kernel.org> References: <20170726083333.17754-1-mhocko@kernel.org> Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: Andrew Morton , Mel Gorman , Vlastimil Babka , Andrea Arcangeli , Jerome Glisse , Reza Arbab , Yasuaki Ishimatsu , qiuxishi@huawei.com, Kani Toshimitsu , slaoub@gmail.com, Joonsoo Kim , Andi Kleen , Daniel Kiper , Igor Mammedov , Vitaly Kuznetsov , LKML , Michal Hocko , Benjamin Herrenschmidt , Dan Williams , "H. Peter Anvin" , Ingo Molnar , Michael Ellerman , Paul Mackerras , Thomas Gleixner From: Michal Hocko Physical memory hotadd has to allocate a memmap (struct page array) for the newly added memory section. kmalloc is currantly used for those allocations. This has some disadvantages a) an existing memory is consumed for that purpose (~2MB per 128MB memory section) and b) if the whole node is movable then we have off-node struct pages which has performance drawbacks. a) has turned out to be a problem for memory hotplug based ballooning because the userspace might not react in time to online memory while to memory consumed during physical hotadd consumes enough memory to push system to OOM. 31bc3858ea3e ("memory-hotplug: add automatic onlining policy for the newly added memory") has been added to workaround that problem. We can do much better when CONFIG_SPARSEMEM_VMEMMAP=y because vmemap page tables can map arbitrary memory. That means that we can simply use the beginning of each memory section and map struct pages there. struct pages which back the allocated space then just need to be treated carefully so that we know they are not usable. Add {_Set,_Clear}PageVmemmap helpers to distinguish those pages in pfn walkers. We do not have any spare page flag for this purpose so use the combination of PageReserved bit which already tells that the page should be ignored by the core mm code and store VMEMMAP_PAGE (which sets all bits but PAGE_MAPPING_FLAGS) into page->mapping. On the memory hotplug front reuse vmem_altmap infrastructure to override the default allocator used by __vmemap_populate. Once the memmap is allocated we need a way to mark altmap pfns used for the allocation and this is done by a new vmem_altmap::flush_alloc_pfns callback. mark_vmemmap_pages implementation then simply __SetPageVmemmap all struct pages backing those pfns. The callback is called from sparse_add_one_section after the memmap has been initialized to 0. We also have to be careful about those pages during online and offline operations. They are simply ignored. Finally __ClearPageVmemmap is called when the vmemmap page tables are torn down. Please note that only the memory hotplug is currently using this allocation scheme. The boot time memmap allocation could use the same trick as well but this is not done yet. Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Michael Ellerman Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: x86@kernel.org Cc: Dan Williams Cc: Vitaly Kuznetsov Signed-off-by: Michal Hocko --- arch/powerpc/mm/init_64.c | 5 +++++ arch/x86/mm/init_64.c | 9 +++++++++ include/linux/memory_hotplug.h | 5 ++++- include/linux/memremap.h | 25 ++++++++++++++++++++++++- include/linux/mm.h | 6 ++---- include/linux/page-flags.h | 18 ++++++++++++++++++ kernel/memremap.c | 6 ------ mm/compaction.c | 3 +++ mm/memory_hotplug.c | 23 ++++++++++++++++++++--- mm/page_alloc.c | 14 ++++++++++++++ mm/page_isolation.c | 11 ++++++++++- mm/sparse-vmemmap.c | 11 +++++++++-- mm/sparse.c | 26 +++++++++++++++++++++----- 13 files changed, 139 insertions(+), 23 deletions(-) diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c index 5ea5e870a589..b14f2239a152 100644 --- a/arch/powerpc/mm/init_64.c +++ b/arch/powerpc/mm/init_64.c @@ -264,6 +264,11 @@ void __ref vmemmap_free(unsigned long start, unsigned long end) goto unmap; } + if (PageVmemmap(page)) { + __ClearPageVmemmap(page); + goto unmap; + } + if (PageReserved(page)) { /* allocated from bootmem */ if (page_size < PAGE_SIZE) { diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index cfe01150f24f..e4f749e5652f 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -803,6 +803,15 @@ static void __meminit free_pagetable(struct page *page, int order) return; } + /* + * runtime vmemmap pages are residing inside the memory section so + * they do not have to be freed anywhere. + */ + if (PageVmemmap(page)) { + __ClearPageVmemmap(page); + return; + } + /* bootmem page has reserved flag */ if (PageReserved(page)) { __ClearPageReserved(page); diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h index 8e8738a6e76d..f2636ad2d00f 100644 --- a/include/linux/memory_hotplug.h +++ b/include/linux/memory_hotplug.h @@ -312,7 +312,10 @@ extern void move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn, 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); -extern int sparse_add_one_section(struct pglist_data *pgdat, unsigned long start_pfn); + +struct vmem_altmap; +extern int sparse_add_one_section(struct pglist_data *pgdat, unsigned long start_pfn, + struct vmem_altmap *altmap); extern void sparse_remove_one_section(struct zone *zone, struct mem_section *ms, unsigned long map_offset); extern struct page *sparse_decode_mem_map(unsigned long coded_mem_map, diff --git a/include/linux/memremap.h b/include/linux/memremap.h index 6f8f65d8ebdd..7aec9272fe4d 100644 --- a/include/linux/memremap.h +++ b/include/linux/memremap.h @@ -14,6 +14,8 @@ struct device; * @free: free pages set aside in the mapping for memmap storage * @align: pages reserved to meet allocation alignments * @alloc: track pages consumed, private to __vmemmap_populate() + * @flush_alloc_pfns: callback to be called on the allocated range after it + * is mapped to the vmemmap - see mark_vmemmap_pages */ struct vmem_altmap { const unsigned long base_pfn; @@ -21,11 +23,32 @@ struct vmem_altmap { unsigned long free; unsigned long align; unsigned long alloc; + void (*flush_alloc_pfns)(struct vmem_altmap *self); }; -unsigned long vmem_altmap_offset(struct vmem_altmap *altmap); +static inline unsigned long vmem_altmap_offset(struct vmem_altmap *altmap) +{ + /* number of pfns from base where pfn_to_page() is valid */ + return altmap->reserve + altmap->free; +} void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns); +static inline void mark_vmemmap_pages(struct vmem_altmap *self) +{ + unsigned long pfn = self->base_pfn + self->reserve; + unsigned long nr_pages = self->alloc; + unsigned long i; + + /* + * All allocations for the memory hotplug are the same sized so align + * should be 0 + */ + WARN_ON(self->align); + for (i = 0; i < nr_pages; i++, pfn++) { + struct page *page = pfn_to_page(pfn); + __SetPageVmemmap(page); + } +} /** * struct dev_pagemap - metadata for ZONE_DEVICE mappings * @altmap: pre-allocated/reserved memory for vmemmap allocations diff --git a/include/linux/mm.h b/include/linux/mm.h index 957d4658977d..3ce673570fb8 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2426,6 +2426,8 @@ void sparse_mem_maps_populate_node(struct page **map_map, unsigned long map_count, int nodeid); +struct page *__sparse_mem_map_populate(unsigned long pnum, int nid, + struct vmem_altmap *altmap); struct page *sparse_mem_map_populate(unsigned long pnum, int nid); pgd_t *vmemmap_pgd_populate(unsigned long addr, int node); p4d_t *vmemmap_p4d_populate(pgd_t *pgd, unsigned long addr, int node); @@ -2436,10 +2438,6 @@ void *vmemmap_alloc_block(unsigned long size, int node); struct vmem_altmap; void *__vmemmap_alloc_block_buf(unsigned long size, int node, struct vmem_altmap *altmap); -static inline void *vmemmap_alloc_block_buf(unsigned long size, int node) -{ - return __vmemmap_alloc_block_buf(size, node, NULL); -} #ifdef CONFIG_ZONE_DEVICE struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start); diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index d33e3280c8ad..a6d4f94cf7bf 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -412,6 +412,24 @@ static __always_inline int __PageMovable(struct page *page) PAGE_MAPPING_MOVABLE; } +#define VMEMMAP_PAGE ~PAGE_MAPPING_FLAGS +static __always_inline int PageVmemmap(struct page *page) +{ + return PageReserved(page) && (unsigned long)page->mapping == VMEMMAP_PAGE; +} + +static __always_inline void __ClearPageVmemmap(struct page *page) +{ + ClearPageReserved(page); + page->mapping = NULL; +} + +static __always_inline void __SetPageVmemmap(struct page *page) +{ + SetPageReserved(page); + page->mapping = (void *)VMEMMAP_PAGE; +} + #ifdef CONFIG_KSM /* * A KSM page is one of those write-protected "shared pages" or "merged pages" diff --git a/kernel/memremap.c b/kernel/memremap.c index 124bed776532..a72eb5932d2f 100644 --- a/kernel/memremap.c +++ b/kernel/memremap.c @@ -393,12 +393,6 @@ void *devm_memremap_pages(struct device *dev, struct resource *res, } EXPORT_SYMBOL(devm_memremap_pages); -unsigned long vmem_altmap_offset(struct vmem_altmap *altmap) -{ - /* number of pfns from base where pfn_to_page() is valid */ - return altmap->reserve + altmap->free; -} - void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns) { altmap->alloc -= nr_pfns; diff --git a/mm/compaction.c b/mm/compaction.c index fb548e4c7bd4..1ba5ad029258 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -741,6 +741,9 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, page = pfn_to_page(low_pfn); + if (PageVmemmap(page)) + goto isolate_fail; + if (!valid_page) valid_page = page; diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 260139f2581c..19037d0191e5 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -35,6 +35,7 @@ #include #include #include +#include #include @@ -244,7 +245,7 @@ void __init register_page_bootmem_info_node(struct pglist_data *pgdat) #endif /* CONFIG_HAVE_BOOTMEM_INFO_NODE */ static int __meminit __add_section(int nid, unsigned long phys_start_pfn, - bool want_memblock) + bool want_memblock, struct vmem_altmap *altmap) { int ret; int i; @@ -252,7 +253,7 @@ static int __meminit __add_section(int nid, unsigned long phys_start_pfn, if (pfn_valid(phys_start_pfn)) return -EEXIST; - ret = sparse_add_one_section(NODE_DATA(nid), phys_start_pfn); + ret = sparse_add_one_section(NODE_DATA(nid), phys_start_pfn, altmap); if (ret < 0) return ret; @@ -292,12 +293,23 @@ int __ref __add_pages(int nid, unsigned long phys_start_pfn, int err = 0; int start_sec, end_sec; struct vmem_altmap *altmap; + struct vmem_altmap __section_altmap = {.base_pfn = phys_start_pfn}; /* during initialize mem_map, align hot-added range to section */ start_sec = pfn_to_section_nr(phys_start_pfn); end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1); + /* + * Check device specific altmap and fallback to allocating from the + * begining of the section otherwise + */ altmap = to_vmem_altmap((unsigned long) pfn_to_page(phys_start_pfn)); + if (!altmap) { + __section_altmap.free = nr_pages; + __section_altmap.flush_alloc_pfns = mark_vmemmap_pages; + altmap = &__section_altmap; + } + if (altmap) { /* * Validate altmap is within bounds of the total request @@ -312,7 +324,7 @@ int __ref __add_pages(int nid, unsigned long phys_start_pfn, } for (i = start_sec; i <= end_sec; i++) { - err = __add_section(nid, section_nr_to_pfn(i), want_memblock); + err = __add_section(nid, section_nr_to_pfn(i), want_memblock, altmap); /* * EEXIST is finally dealt with by ioresource collision @@ -689,6 +701,8 @@ static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages, if (PageReserved(pfn_to_page(start_pfn))) for (i = 0; i < nr_pages; i++) { page = pfn_to_page(start_pfn + i); + if (PageVmemmap(page)) + continue; if (PageHWPoison(page)) { ClearPageReserved(page); continue; @@ -1406,6 +1420,9 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn) continue; page = pfn_to_page(pfn); + if (PageVmemmap(page)) + continue; + if (PageHuge(page)) { struct page *head = compound_head(page); pfn = page_to_pfn(head) + (1< #include #include +#include #include "internal.h" #include @@ -666,10 +667,11 @@ void offline_mem_sections(unsigned long start_pfn, unsigned long end_pfn) #endif #ifdef CONFIG_SPARSEMEM_VMEMMAP -static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid) +static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid, + struct vmem_altmap *altmap) { /* This will make the necessary allocations eventually. */ - return sparse_mem_map_populate(pnum, nid); + return __sparse_mem_map_populate(pnum, nid, altmap); } static void __kfree_section_memmap(struct page *memmap) { @@ -709,7 +711,8 @@ static struct page *__kmalloc_section_memmap(void) return ret; } -static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid) +static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid, + struct vmem_altmap *altmap) { return __kmalloc_section_memmap(); } @@ -761,7 +764,8 @@ static void free_map_bootmem(struct page *memmap) * set. If this is <=0, then that means that the passed-in * map was not consumed and must be freed. */ -int __meminit sparse_add_one_section(struct pglist_data *pgdat, unsigned long start_pfn) +int __meminit sparse_add_one_section(struct pglist_data *pgdat, unsigned long start_pfn, + struct vmem_altmap *altmap) { unsigned long section_nr = pfn_to_section_nr(start_pfn); struct mem_section *ms; @@ -777,7 +781,7 @@ int __meminit sparse_add_one_section(struct pglist_data *pgdat, unsigned long st ret = sparse_index_init(section_nr, pgdat->node_id); if (ret < 0 && ret != -EEXIST) return ret; - memmap = kmalloc_section_memmap(section_nr, pgdat->node_id); + memmap = kmalloc_section_memmap(section_nr, pgdat->node_id, altmap); if (!memmap) return -ENOMEM; usemap = __kmalloc_section_usemap(); @@ -794,8 +798,20 @@ int __meminit sparse_add_one_section(struct pglist_data *pgdat, unsigned long st goto out; } + /* + * TODO get rid of this somehow - we want to postpone the full + * initialization until memmap_init_zone. + */ memset(memmap, 0, sizeof(struct page) * PAGES_PER_SECTION); + /* + * now that we have a valid vmemmap mapping we can use + * pfn_to_page and flush struct pages which back the + * memmap + */ + if (altmap && altmap->flush_alloc_pfns) + altmap->flush_alloc_pfns(altmap); + section_mark_present(ms); ret = sparse_init_one_section(ms, section_nr, memmap, usemap); -- 2.13.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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