patches/kernel/0074-mm-sparsemem-Allocate-mem_section-at-runtime-for-CON.patch

   1 From cc87e9d44044fb3ae4145d6ad9574697439b03bf Mon Sep 17 00:00:00 2001
   2 From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
   3 Date: Fri, 29 Sep 2017 17:08:16 +0300
   4 Subject: [PATCH 074/233] mm/sparsemem: Allocate mem_section at runtime for
   5  CONFIG_SPARSEMEM_EXTREME=y
   6 MIME-Version: 1.0
   7 Content-Type: text/plain; charset=UTF-8
   8 Content-Transfer-Encoding: 8bit
   9
  10 CVE-2017-5754
  11
  12 Size of the mem_section[] array depends on the size of the physical address space.
  13
  14 In preparation for boot-time switching between paging modes on x86-64
  15 we need to make the allocation of mem_section[] dynamic, because otherwise
  16 we waste a lot of RAM: with CONFIG_NODE_SHIFT=10, mem_section[] size is 32kB
  17 for 4-level paging and 2MB for 5-level paging mode.
  18
  19 The patch allocates the array on the first call to sparse_memory_present_with_active_regions().
  20
  21 Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
  22 Cc: Andrew Morton <akpm@linux-foundation.org>
  23 Cc: Andy Lutomirski <luto@amacapital.net>
  24 Cc: Borislav Petkov <bp@suse.de>
  25 Cc: Cyrill Gorcunov <gorcunov@openvz.org>
  26 Cc: Linus Torvalds <torvalds@linux-foundation.org>
  27 Cc: Peter Zijlstra <peterz@infradead.org>
  28 Cc: Thomas Gleixner <tglx@linutronix.de>
  29 Cc: linux-mm@kvack.org
  30 Link: http://lkml.kernel.org/r/20170929140821.37654-2-kirill.shutemov@linux.intel.com
  31 Signed-off-by: Ingo Molnar <mingo@kernel.org>
  32 (cherry picked from commit 83e3c48729d9ebb7af5a31a504f3fd6aff0348c4)
  33 Signed-off-by: Andy Whitcroft <apw@canonical.com>
  34 Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
  35 (cherry picked from commit c70f71e01a0ae5d884abae0424618abe90b82011)
  36 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  37 ---
  38  include/linux/mmzone.h |  6 +++++-
  39  mm/page_alloc.c        | 10 ++++++++++
  40  mm/sparse.c            | 17 +++++++++++------
  41  3 files changed, 26 insertions(+), 7 deletions(-)
  42
  43 diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
  44 index fc14b8b3f6ce..9c6c001a8c6c 100644
  45 --- a/include/linux/mmzone.h
  46 +++ b/include/linux/mmzone.h
  47 @@ -1137,13 +1137,17 @@ struct mem_section {
  48  #define SECTION_ROOT_MASK      (SECTIONS_PER_ROOT - 1)
  49
  50  #ifdef CONFIG_SPARSEMEM_EXTREME
  51 -extern struct mem_section *mem_section[NR_SECTION_ROOTS];
  52 +extern struct mem_section **mem_section;
  53  #else
  54  extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
  55  #endif
  56
  57  static inline struct mem_section *__nr_to_section(unsigned long nr)
  58  {
  59 +#ifdef CONFIG_SPARSEMEM_EXTREME
  60 +       if (!mem_section)
  61 +               return NULL;
  62 +#endif
  63         if (!mem_section[SECTION_NR_TO_ROOT(nr)])
  64                 return NULL;
  65         return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK];
  66 diff --git a/mm/page_alloc.c b/mm/page_alloc.c
  67 index 1423da8dd16f..66eb23ab658d 100644
  68 --- a/mm/page_alloc.c
  69 +++ b/mm/page_alloc.c
  70 @@ -5707,6 +5707,16 @@ void __init sparse_memory_present_with_active_regions(int nid)
  71         unsigned long start_pfn, end_pfn;
  72         int i, this_nid;
  73
  74 +#ifdef CONFIG_SPARSEMEM_EXTREME
  75 +       if (!mem_section) {
  76 +               unsigned long size, align;
  77 +
  78 +               size = sizeof(struct mem_section) * NR_SECTION_ROOTS;
  79 +               align = 1 << (INTERNODE_CACHE_SHIFT);
  80 +               mem_section = memblock_virt_alloc(size, align);
  81 +       }
  82 +#endif
  83 +
  84         for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, &this_nid)
  85                 memory_present(this_nid, start_pfn, end_pfn);
  86  }
  87 diff --git a/mm/sparse.c b/mm/sparse.c
  88 index cdce7a7bb3f3..308a0789d1bb 100644
  89 --- a/mm/sparse.c
  90 +++ b/mm/sparse.c
  91 @@ -22,8 +22,7 @@
  92   * 1) mem_section      - memory sections, mem_map's for valid memory
  93   */
  94  #ifdef CONFIG_SPARSEMEM_EXTREME
  95 -struct mem_section *mem_section[NR_SECTION_ROOTS]
  96 -       ____cacheline_internodealigned_in_smp;
  97 +struct mem_section **mem_section;
  98  #else
  99  struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
 100         ____cacheline_internodealigned_in_smp;
 101 @@ -104,7 +103,7 @@ static inline int sparse_index_init(unsigned long section_nr, int nid)
 102  int __section_nr(struct mem_section* ms)
 103  {
 104         unsigned long root_nr;
 105 -       struct mem_section* root;
 106 +       struct mem_section *root = NULL;
 107
 108         for (root_nr = 0; root_nr < NR_SECTION_ROOTS; root_nr++) {
 109                 root = __nr_to_section(root_nr * SECTIONS_PER_ROOT);
 110 @@ -115,7 +114,7 @@ int __section_nr(struct mem_section* ms)
 111                      break;
 112         }
 113
 114 -       VM_BUG_ON(root_nr == NR_SECTION_ROOTS);
 115 +       VM_BUG_ON(!root);
 116
 117         return (root_nr * SECTIONS_PER_ROOT) + (ms - root);
 118  }
 119 @@ -333,11 +332,17 @@ sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
 120  static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
 121  {
 122         unsigned long usemap_snr, pgdat_snr;
 123 -       static unsigned long old_usemap_snr = NR_MEM_SECTIONS;
 124 -       static unsigned long old_pgdat_snr = NR_MEM_SECTIONS;
 125 +       static unsigned long old_usemap_snr;
 126 +       static unsigned long old_pgdat_snr;
 127         struct pglist_data *pgdat = NODE_DATA(nid);
 128         int usemap_nid;
 129
 130 +       /* First call */
 131 +       if (!old_usemap_snr) {
 132 +               old_usemap_snr = NR_MEM_SECTIONS;
 133 +               old_pgdat_snr = NR_MEM_SECTIONS;
 134 +       }
 135 +
 136         usemap_snr = pfn_to_section_nr(__pa(usemap) >> PAGE_SHIFT);
 137         pgdat_snr = pfn_to_section_nr(__pa(pgdat) >> PAGE_SHIFT);
 138         if (usemap_snr == pgdat_snr)
 139 --
 140 2.14.2
 141