mm/hugetlb.c

   1 /*
   2  * Generic hugetlb support.
   3  * (C) William Irwin, April 2004
   4  */
   5 #include <linux/gfp.h>
   6 #include <linux/list.h>
   7 #include <linux/init.h>
   8 #include <linux/module.h>
   9 #include <linux/mm.h>
  10 #include <linux/hugetlb.h>
  11 #include <linux/sysctl.h>
  12 #include <linux/highmem.h>
  13 #include <linux/nodemask.h>
  14
  15 const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
  16 static unsigned long nr_huge_pages, free_huge_pages;
  17 unsigned long max_huge_pages;
  18 static struct list_head hugepage_freelists[MAX_NUMNODES];
  19 static unsigned int nr_huge_pages_node[MAX_NUMNODES];
  20 static unsigned int free_huge_pages_node[MAX_NUMNODES];
  21 static DEFINE_SPINLOCK(hugetlb_lock);
  22
  23 static void enqueue_huge_page(struct page *page)
  24 {
  25         int nid = page_to_nid(page);
  26         list_add(&page->lru, &hugepage_freelists[nid]);
  27         free_huge_pages++;
  28         free_huge_pages_node[nid]++;
  29 }
  30
  31 static struct page *dequeue_huge_page(void)
  32 {
  33         int nid = numa_node_id();
  34         struct page *page = NULL;
  35
  36         if (list_empty(&hugepage_freelists[nid])) {
  37                 for (nid = 0; nid < MAX_NUMNODES; ++nid)
  38                         if (!list_empty(&hugepage_freelists[nid]))
  39                                 break;
  40         }
  41         if (nid >= 0 && nid < MAX_NUMNODES &&
  42             !list_empty(&hugepage_freelists[nid])) {
  43                 page = list_entry(hugepage_freelists[nid].next,
  44                                   struct page, lru);
  45                 list_del(&page->lru);
  46                 free_huge_pages--;
  47                 free_huge_pages_node[nid]--;
  48         }
  49         return page;
  50 }
  51
  52 static struct page *alloc_fresh_huge_page(void)
  53 {
  54         static int nid = 0;
  55         struct page *page;
  56         page = alloc_pages_node(nid, GFP_HIGHUSER|__GFP_COMP|__GFP_NOWARN,
  57                                         HUGETLB_PAGE_ORDER);
  58         nid = (nid + 1) % num_online_nodes();
  59         if (page) {
  60                 nr_huge_pages++;
  61                 nr_huge_pages_node[page_to_nid(page)]++;
  62         }
  63         return page;
  64 }
  65
  66 void free_huge_page(struct page *page)
  67 {
  68         BUG_ON(page_count(page));
  69
  70         INIT_LIST_HEAD(&page->lru);
  71         page[1].mapping = NULL;
  72
  73         spin_lock(&hugetlb_lock);
  74         enqueue_huge_page(page);
  75         spin_unlock(&hugetlb_lock);
  76 }
  77
  78 struct page *alloc_huge_page(void)
  79 {
  80         struct page *page;
  81         int i;
  82
  83         spin_lock(&hugetlb_lock);
  84         page = dequeue_huge_page();
  85         if (!page) {
  86                 spin_unlock(&hugetlb_lock);
  87                 return NULL;
  88         }
  89         spin_unlock(&hugetlb_lock);
  90         set_page_count(page, 1);
  91         page[1].mapping = (void *)free_huge_page;
  92         for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); ++i)
  93                 clear_highpage(&page[i]);
  94         return page;
  95 }
  96
  97 static int __init hugetlb_init(void)
  98 {
  99         unsigned long i;
 100         struct page *page;
 101
 102         for (i = 0; i < MAX_NUMNODES; ++i)
 103                 INIT_LIST_HEAD(&hugepage_freelists[i]);
 104
 105         for (i = 0; i < max_huge_pages; ++i) {
 106                 page = alloc_fresh_huge_page();
 107                 if (!page)
 108                         break;
 109                 spin_lock(&hugetlb_lock);
 110                 enqueue_huge_page(page);
 111                 spin_unlock(&hugetlb_lock);
 112         }
 113         max_huge_pages = free_huge_pages = nr_huge_pages = i;
 114         printk("Total HugeTLB memory allocated, %ld\n", free_huge_pages);
 115         return 0;
 116 }
 117 module_init(hugetlb_init);
 118
 119 static int __init hugetlb_setup(char *s)
 120 {
 121         if (sscanf(s, "%lu", &max_huge_pages) <= 0)
 122                 max_huge_pages = 0;
 123         return 1;
 124 }
 125 __setup("hugepages=", hugetlb_setup);
 126
 127 #ifdef CONFIG_SYSCTL
 128 static void update_and_free_page(struct page *page)
 129 {
 130         int i;
 131         nr_huge_pages--;
 132         nr_huge_pages_node[page_zone(page)->zone_pgdat->node_id]--;
 133         for (i = 0; i < (HPAGE_SIZE / PAGE_SIZE); i++) {
 134                 page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
 135                                 1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
 136                                 1 << PG_private | 1<< PG_writeback);
 137                 set_page_count(&page[i], 0);
 138         }
 139         set_page_count(page, 1);
 140         __free_pages(page, HUGETLB_PAGE_ORDER);
 141 }
 142
 143 #ifdef CONFIG_HIGHMEM
 144 static void try_to_free_low(unsigned long count)
 145 {
 146         int i, nid;
 147         for (i = 0; i < MAX_NUMNODES; ++i) {
 148                 struct page *page, *next;
 149                 list_for_each_entry_safe(page, next, &hugepage_freelists[i], lru) {
 150                         if (PageHighMem(page))
 151                                 continue;
 152                         list_del(&page->lru);
 153                         update_and_free_page(page);
 154                         nid = page_zone(page)->zone_pgdat->node_id;
 155                         free_huge_pages--;
 156                         free_huge_pages_node[nid]--;
 157                         if (count >= nr_huge_pages)
 158                                 return;
 159                 }
 160         }
 161 }
 162 #else
 163 static inline void try_to_free_low(unsigned long count)
 164 {
 165 }
 166 #endif
 167
 168 static unsigned long set_max_huge_pages(unsigned long count)
 169 {
 170         while (count > nr_huge_pages) {
 171                 struct page *page = alloc_fresh_huge_page();
 172                 if (!page)
 173                         return nr_huge_pages;
 174                 spin_lock(&hugetlb_lock);
 175                 enqueue_huge_page(page);
 176                 spin_unlock(&hugetlb_lock);
 177         }
 178         if (count >= nr_huge_pages)
 179                 return nr_huge_pages;
 180
 181         spin_lock(&hugetlb_lock);
 182         try_to_free_low(count);
 183         while (count < nr_huge_pages) {
 184                 struct page *page = dequeue_huge_page();
 185                 if (!page)
 186                         break;
 187                 update_and_free_page(page);
 188         }
 189         spin_unlock(&hugetlb_lock);
 190         return nr_huge_pages;
 191 }
 192
 193 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
 194                            struct file *file, void __user *buffer,
 195                            size_t *length, loff_t *ppos)
 196 {
 197         proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
 198         max_huge_pages = set_max_huge_pages(max_huge_pages);
 199         return 0;
 200 }
 201 #endif /* CONFIG_SYSCTL */
 202
 203 int hugetlb_report_meminfo(char *buf)
 204 {
 205         return sprintf(buf,
 206                         "HugePages_Total: %5lu\n"
 207                         "HugePages_Free:  %5lu\n"
 208                         "Hugepagesize:    %5lu kB\n",
 209                         nr_huge_pages,
 210                         free_huge_pages,
 211                         HPAGE_SIZE/1024);
 212 }
 213
 214 int hugetlb_report_node_meminfo(int nid, char *buf)
 215 {
 216         return sprintf(buf,
 217                 "Node %d HugePages_Total: %5u\n"
 218                 "Node %d HugePages_Free:  %5u\n",
 219                 nid, nr_huge_pages_node[nid],
 220                 nid, free_huge_pages_node[nid]);
 221 }
 222
 223 int is_hugepage_mem_enough(size_t size)
 224 {
 225         return (size + ~HPAGE_MASK)/HPAGE_SIZE <= free_huge_pages;
 226 }
 227
 228 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
 229 unsigned long hugetlb_total_pages(void)
 230 {
 231         return nr_huge_pages * (HPAGE_SIZE / PAGE_SIZE);
 232 }
 233 EXPORT_SYMBOL(hugetlb_total_pages);
 234
 235 /*
 236  * We cannot handle pagefaults against hugetlb pages at all.  They cause
 237  * handle_mm_fault() to try to instantiate regular-sized pages in the
 238  * hugegpage VMA.  do_page_fault() is supposed to trap this, so BUG is we get
 239  * this far.
 240  */
 241 static struct page *hugetlb_nopage(struct vm_area_struct *vma,
 242                                 unsigned long address, int *unused)
 243 {
 244         BUG();
 245         return NULL;
 246 }
 247
 248 struct vm_operations_struct hugetlb_vm_ops = {
 249         .nopage = hugetlb_nopage,
 250 };
 251
 252 void zap_hugepage_range(struct vm_area_struct *vma,
 253                         unsigned long start, unsigned long length)
 254 {
 255         struct mm_struct *mm = vma->vm_mm;
 256
 257         spin_lock(&mm->page_table_lock);
 258         unmap_hugepage_range(vma, start, start + length);
 259         spin_unlock(&mm->page_table_lock);
 260 }