From 4afaf6ea65acb07e151470580d89e6a2c0268610 Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Fri, 29 Sep 2017 17:08:16 +0300 Subject: [PATCH] mm/sparsemem: Allocate mem_section at runtime for CONFIG_SPARSEMEM_EXTREME=y commit 83e3c48729d9ebb7af5a31a504f3fd6aff0348c4 upstream. Size of the mem_section[] array depends on the size of the physical address space. In preparation for boot-time switching between paging modes on x86-64 we need to make the allocation of mem_section[] dynamic, because otherwise we waste a lot of RAM: with CONFIG_NODE_SHIFT=10, mem_section[] size is 32kB for 4-level paging and 2MB for 5-level paging mode. The patch allocates the array on the first call to sparse_memory_present_with_active_regions(). Signed-off-by: Kirill A. Shutemov Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Cyrill Gorcunov Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20170929140821.37654-2-kirill.shutemov@linux.intel.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- include/linux/mmzone.h | 6 +++++- mm/page_alloc.c | 10 ++++++++++ mm/sparse.c | 17 +++++++++++------ 3 files changed, 26 insertions(+), 7 deletions(-) diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 18b06983131a..f0938257ee6d 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -1152,13 +1152,17 @@ struct mem_section { #define SECTION_ROOT_MASK (SECTIONS_PER_ROOT - 1) #ifdef CONFIG_SPARSEMEM_EXTREME -extern struct mem_section *mem_section[NR_SECTION_ROOTS]; +extern struct mem_section **mem_section; #else extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]; #endif static inline struct mem_section *__nr_to_section(unsigned long nr) { +#ifdef CONFIG_SPARSEMEM_EXTREME + if (!mem_section) + return NULL; +#endif if (!mem_section[SECTION_NR_TO_ROOT(nr)]) return NULL; return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK]; diff --git a/mm/page_alloc.c b/mm/page_alloc.c index d51c2087c498..02cf30bd01cd 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5651,6 +5651,16 @@ void __init sparse_memory_present_with_active_regions(int nid) unsigned long start_pfn, end_pfn; int i, this_nid; +#ifdef CONFIG_SPARSEMEM_EXTREME + if (!mem_section) { + unsigned long size, align; + + size = sizeof(struct mem_section) * NR_SECTION_ROOTS; + align = 1 << (INTERNODE_CACHE_SHIFT); + mem_section = memblock_virt_alloc(size, align); + } +#endif + for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, &this_nid) memory_present(this_nid, start_pfn, end_pfn); } diff --git a/mm/sparse.c b/mm/sparse.c index 4900707ae146..044138852baf 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -23,8 +23,7 @@ * 1) mem_section - memory sections, mem_map's for valid memory */ #ifdef CONFIG_SPARSEMEM_EXTREME -struct mem_section *mem_section[NR_SECTION_ROOTS] - ____cacheline_internodealigned_in_smp; +struct mem_section **mem_section; #else struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT] ____cacheline_internodealigned_in_smp; @@ -101,7 +100,7 @@ static inline int sparse_index_init(unsigned long section_nr, int nid) int __section_nr(struct mem_section* ms) { unsigned long root_nr; - struct mem_section* root; + struct mem_section *root = NULL; for (root_nr = 0; root_nr < NR_SECTION_ROOTS; root_nr++) { root = __nr_to_section(root_nr * SECTIONS_PER_ROOT); @@ -112,7 +111,7 @@ int __section_nr(struct mem_section* ms) break; } - VM_BUG_ON(root_nr == NR_SECTION_ROOTS); + VM_BUG_ON(!root); return (root_nr * SECTIONS_PER_ROOT) + (ms - root); } @@ -330,11 +329,17 @@ again: static void __init check_usemap_section_nr(int nid, unsigned long *usemap) { unsigned long usemap_snr, pgdat_snr; - static unsigned long old_usemap_snr = NR_MEM_SECTIONS; - static unsigned long old_pgdat_snr = NR_MEM_SECTIONS; + static unsigned long old_usemap_snr; + static unsigned long old_pgdat_snr; struct pglist_data *pgdat = NODE_DATA(nid); int usemap_nid; + /* First call */ + if (!old_usemap_snr) { + old_usemap_snr = NR_MEM_SECTIONS; + old_pgdat_snr = NR_MEM_SECTIONS; + } + usemap_snr = pfn_to_section_nr(__pa(usemap) >> PAGE_SHIFT); pgdat_snr = pfn_to_section_nr(__pa(pgdat) >> PAGE_SHIFT); if (usemap_snr == pgdat_snr) -- 2.20.1