arch/i386/mm/init.c

   1 /*
   2  *  linux/arch/i386/mm/init.c
   3  *
   4  *  Copyright (C) 1995  Linus Torvalds
   5  *
   6  *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
   7  */
   8
   9 #include <linux/config.h>
  10 #include <linux/module.h>
  11 #include <linux/signal.h>
  12 #include <linux/sched.h>
  13 #include <linux/kernel.h>
  14 #include <linux/errno.h>
  15 #include <linux/string.h>
  16 #include <linux/types.h>
  17 #include <linux/ptrace.h>
  18 #include <linux/mman.h>
  19 #include <linux/mm.h>
  20 #include <linux/hugetlb.h>
  21 #include <linux/swap.h>
  22 #include <linux/smp.h>
  23 #include <linux/init.h>
  24 #include <linux/highmem.h>
  25 #include <linux/pagemap.h>
  26 #include <linux/bootmem.h>
  27 #include <linux/slab.h>
  28 #include <linux/proc_fs.h>
  29 #include <linux/efi.h>
  30
  31 #include <asm/processor.h>
  32 #include <asm/system.h>
  33 #include <asm/uaccess.h>
  34 #include <asm/pgtable.h>
  35 #include <asm/pgalloc.h>
  36 #include <asm/dma.h>
  37 #include <asm/fixmap.h>
  38 #include <asm/e820.h>
  39 #include <asm/apic.h>
  40 #include <asm/tlb.h>
  41 #include <asm/tlbflush.h>
  42 #include <asm/sections.h>
  43 #include <asm/desc.h>
  44
  45 DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
  46 unsigned long highstart_pfn, highend_pfn;
  47
  48 static int do_test_wp_bit(void);
  49
  50 static inline int page_kills_ppro(unsigned long pagenr)
  51 {
  52         if (pagenr >= 0x70000 && pagenr <= 0x7003F)
  53                 return 1;
  54         return 0;
  55 }
  56
  57 extern int is_available_memory(efi_memory_desc_t *);
  58
  59 int page_is_ram(unsigned long pagenr)
  60 {
  61         int i;
  62         unsigned long addr, end;
  63
  64         if (efi_enabled) {
  65                 efi_memory_desc_t *md;
  66
  67                 for (i = 0; i < memmap.nr_map; i++) {
  68                         md = &memmap.map[i];
  69                         if (!is_available_memory(md))
  70                                 continue;
  71                         addr = (md->phys_addr+PAGE_SIZE-1) >> PAGE_SHIFT;
  72                         end = (md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT)) >> PAGE_SHIFT;
  73
  74                         if ((pagenr >= addr) && (pagenr < end))
  75                                 return 1;
  76                 }
  77                 return 0;
  78         }
  79
  80         for (i = 0; i < e820.nr_map; i++) {
  81
  82                 if (e820.map[i].type != E820_RAM)       /* not usable memory */
  83                         continue;
  84                 /*
  85                  *      !!!FIXME!!! Some BIOSen report areas as RAM that
  86                  *      are not. Notably the 640->1Mb area. We need a sanity
  87                  *      check here.
  88                  */
  89                 addr = (e820.map[i].addr+PAGE_SIZE-1) >> PAGE_SHIFT;
  90                 end = (e820.map[i].addr+e820.map[i].size) >> PAGE_SHIFT;
  91                 if  ((pagenr >= addr) && (pagenr < end))
  92                         return 1;
  93         }
  94         return 0;
  95 }
  96
  97 pte_t *kmap_pte;
  98
  99 EXPORT_SYMBOL(kmap_pte);
 100
 101 #define kmap_get_fixmap_pte(vaddr)                                      \
 102         pte_offset_kernel(pmd_offset(pgd_offset_k(vaddr), (vaddr)), (vaddr))
 103
 104 void __init kmap_init(void)
 105 {
 106         kmap_pte = kmap_get_fixmap_pte(__fix_to_virt(FIX_KMAP_BEGIN));
 107 }
 108
 109 void __init one_highpage_init(struct page *page, int pfn, int bad_ppro)
 110 {
 111         if (page_is_ram(pfn) && !(bad_ppro && page_kills_ppro(pfn))) {
 112                 ClearPageReserved(page);
 113                 set_bit(PG_highmem, &page->flags);
 114                 set_page_count(page, 1);
 115                 __free_page(page);
 116                 totalhigh_pages++;
 117         } else
 118                 SetPageReserved(page);
 119 }
 120
 121 EXPORT_SYMBOL_GPL(page_is_ram);
 122
 123 #ifdef CONFIG_HIGHMEM
 124
 125 #ifndef CONFIG_DISCONTIGMEM
 126 void __init set_highmem_pages_init(int bad_ppro)
 127 {
 128         int pfn;
 129         for (pfn = highstart_pfn; pfn < highend_pfn; pfn++)
 130                 one_highpage_init(pfn_to_page(pfn), pfn, bad_ppro);
 131         totalram_pages += totalhigh_pages;
 132 }
 133 #else
 134 extern void set_highmem_pages_init(int);
 135 #endif /* !CONFIG_DISCONTIGMEM */
 136 #else
 137 # define set_highmem_pages_init(bad_ppro) do { } while (0)
 138 #endif
 139
 140 unsigned long __PAGE_KERNEL = _PAGE_KERNEL;
 141
 142 #ifndef CONFIG_DISCONTIGMEM
 143 #define remap_numa_kva() do {} while (0)
 144 #else
 145 extern void __init remap_numa_kva(void);
 146 #endif
 147
 148 static __init void prepare_pagetables(pgd_t *pgd_base, unsigned long address)
 149 {
 150         pgd_t *pgd;
 151         pmd_t *pmd;
 152         pte_t *pte;
 153
 154         pgd = pgd_base + pgd_index(address);
 155         pmd = pmd_offset(pgd, address);
 156         if (!pmd_present(*pmd)) {
 157                 pte = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
 158                 set_pmd(pmd, __pmd(_PAGE_TABLE + __pa(pte)));
 159         }
 160 }
 161
 162 static void __init fixrange_init (unsigned long start, unsigned long end, pgd_t *pgd_base)
 163 {
 164         unsigned long vaddr;
 165
 166         for (vaddr = start; vaddr != end; vaddr += PAGE_SIZE)
 167                 prepare_pagetables(pgd_base, vaddr);
 168 }
 169
 170 void setup_identity_mappings(pgd_t *pgd_base, unsigned long start, unsigned long end)
 171 {
 172         unsigned long vaddr;
 173         pgd_t *pgd;
 174         int i, j, k;
 175         pmd_t *pmd;
 176         pte_t *pte, *pte_base;
 177
 178         pgd = pgd_base;
 179
 180         for (i = 0; i < PTRS_PER_PGD; pgd++, i++) {
 181                 vaddr = i*PGDIR_SIZE;
 182                 if (end && (vaddr >= end))
 183                         break;
 184                 pmd = pmd_offset(pgd, 0);
 185                 for (j = 0; j < PTRS_PER_PMD; pmd++, j++) {
 186                         vaddr = i*PGDIR_SIZE + j*PMD_SIZE;
 187                         if (end && (vaddr >= end))
 188                                 break;
 189                         if (vaddr < start)
 190                                 continue;
 191                         if (cpu_has_pse) {
 192                                 unsigned long __pe;
 193
 194                                 set_in_cr4(X86_CR4_PSE);
 195                                 boot_cpu_data.wp_works_ok = 1;
 196                                 __pe = _KERNPG_TABLE + _PAGE_PSE + vaddr - start;
 197                                 /* Make it "global" too if supported */
 198                                 if (cpu_has_pge) {
 199                                         set_in_cr4(X86_CR4_PGE);
 200 #if !defined(CONFIG_X86_SWITCH_PAGETABLES)
 201                                         __pe += _PAGE_GLOBAL;
 202                                         __PAGE_KERNEL |= _PAGE_GLOBAL;
 203 #endif
 204                                 }
 205                                 set_pmd(pmd, __pmd(__pe));
 206                                 continue;
 207                         }
 208                         if (!pmd_present(*pmd))
 209                                 pte_base = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
 210                         else
 211                                 pte_base = (pte_t *) pte_offset_kernel(pmd, 0);
 212                         pte = pte_base;
 213                         for (k = 0; k < PTRS_PER_PTE; pte++, k++) {
 214                                 vaddr = i*PGDIR_SIZE + j*PMD_SIZE + k*PAGE_SIZE;
 215                                 if (end && (vaddr >= end))
 216                                         break;
 217                                 if (vaddr < start)
 218                                         continue;
 219                                 *pte = mk_pte_phys(vaddr-start, PAGE_KERNEL);
 220                         }
 221                         set_pmd(pmd, __pmd(_KERNPG_TABLE + __pa(pte_base)));
 222                 }
 223         }
 224 }
 225
 226 static void __init pagetable_init (void)
 227 {
 228         unsigned long vaddr, end;
 229         pgd_t *pgd_base;
 230 #ifdef CONFIG_X86_PAE
 231         int i;
 232 #endif
 233
 234         /*
 235          * This can be zero as well - no problem, in that case we exit
 236          * the loops anyway due to the PTRS_PER_* conditions.
 237          */
 238         end = (unsigned long)__va(max_low_pfn*PAGE_SIZE);
 239
 240         pgd_base = swapper_pg_dir;
 241 #ifdef CONFIG_X86_PAE
 242         /*
 243          * It causes too many problems if there's no proper pmd set up
 244          * for all 4 entries of the PGD - so we allocate all of them.
 245          * PAE systems will not miss this extra 4-8K anyway ...
 246          */
 247         for (i = 0; i < PTRS_PER_PGD; i++) {
 248                 pmd_t *pmd = (pmd_t *) alloc_bootmem_low_pages(PAGE_SIZE);
 249                 set_pgd(pgd_base + i, __pgd(__pa(pmd) + 0x1));
 250         }
 251 #endif
 252         /*
 253          * Set up lowmem-sized identity mappings at PAGE_OFFSET:
 254          */
 255         setup_identity_mappings(pgd_base, PAGE_OFFSET, end);
 256
 257         /*
 258          * Add flat-mode identity-mappings - SMP needs it when
 259          * starting up on an AP from real-mode. (In the non-PAE
 260          * case we already have these mappings through head.S.)
 261          * All user-space mappings are explicitly cleared after
 262          * SMP startup.
 263          */
 264 #if defined(CONFIG_SMP) && defined(CONFIG_X86_PAE)
 265         setup_identity_mappings(pgd_base, 0, 16*1024*1024);
 266 #endif
 267         remap_numa_kva();
 268
 269         /*
 270          * Fixed mappings, only the page table structure has to be
 271          * created - mappings will be set by set_fixmap():
 272          */
 273         vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
 274         fixrange_init(vaddr, 0, pgd_base);
 275
 276 #ifdef CONFIG_HIGHMEM
 277         {
 278                 pgd_t *pgd;
 279                 pmd_t *pmd;
 280                 pte_t *pte;
 281
 282                 /*
 283                  * Permanent kmaps:
 284                  */
 285                 vaddr = PKMAP_BASE;
 286                 fixrange_init(vaddr, vaddr + PAGE_SIZE*LAST_PKMAP, pgd_base);
 287
 288                 pgd = swapper_pg_dir + pgd_index(vaddr);
 289                 pmd = pmd_offset(pgd, vaddr);
 290                 pte = pte_offset_kernel(pmd, vaddr);
 291                 pkmap_page_table = pte;
 292         }
 293 #endif
 294 }
 295
 296 #if defined(CONFIG_PM_DISK) || defined(CONFIG_SOFTWARE_SUSPEND)
 297 /*
 298  * Swap suspend & friends need this for resume because things like the intel-agp
 299  * driver might have split up a kernel 4MB mapping.
 300  */
 301 char __nosavedata swsusp_pg_dir[PAGE_SIZE]
 302         __attribute__ ((aligned (PAGE_SIZE)));
 303
 304 static inline void save_pg_dir(void)
 305 {
 306         memcpy(swsusp_pg_dir, swapper_pg_dir, PAGE_SIZE);
 307 }
 308 #else
 309 static inline void save_pg_dir(void)
 310 {
 311 }
 312 #endif
 313
 314 /*
 315  * Clear kernel pagetables in a PMD_SIZE-aligned range.
 316  */
 317 static void clear_mappings(pgd_t *pgd_base, unsigned long start, unsigned long end)
 318 {
 319         unsigned long vaddr;
 320         pgd_t *pgd;
 321         pmd_t *pmd;
 322         int i, j;
 323
 324         pgd = pgd_base;
 325
 326         for (i = 0; i < PTRS_PER_PGD; pgd++, i++) {
 327                 vaddr = i*PGDIR_SIZE;
 328                 if (end && (vaddr >= end))
 329                         break;
 330                 pmd = pmd_offset(pgd, 0);
 331                 for (j = 0; j < PTRS_PER_PMD; pmd++, j++) {
 332                         vaddr = i*PGDIR_SIZE + j*PMD_SIZE;
 333                         if (end && (vaddr >= end))
 334                                 break;
 335                         if (vaddr < start)
 336                                 continue;
 337                         pmd_clear(pmd);
 338                 }
 339         }
 340         flush_tlb_all();
 341 }
 342
 343 void zap_low_mappings(void)
 344 {
 345         printk("zapping low mappings.\n");
 346
 347         save_pg_dir();
 348
 349         /*
 350          * Zap initial low-memory mappings.
 351          */
 352         clear_mappings(swapper_pg_dir, 0, 16*1024*1024);
 353 }
 354
 355 #ifndef CONFIG_DISCONTIGMEM
 356 void __init zone_sizes_init(void)
 357 {
 358         unsigned long zones_size[MAX_NR_ZONES] = {0, 0, 0};
 359         unsigned int max_dma, high, low;
 360
 361         max_dma = virt_to_phys((char *)MAX_DMA_ADDRESS) >> PAGE_SHIFT;
 362         low = max_low_pfn;
 363         high = highend_pfn;
 364
 365         if (low < max_dma)
 366                 zones_size[ZONE_DMA] = low;
 367         else {
 368                 zones_size[ZONE_DMA] = max_dma;
 369                 zones_size[ZONE_NORMAL] = low - max_dma;
 370 #ifdef CONFIG_HIGHMEM
 371                 zones_size[ZONE_HIGHMEM] = high - low;
 372 #endif
 373         }
 374         free_area_init(zones_size);
 375 }
 376 #else
 377 extern void zone_sizes_init(void);
 378 #endif /* !CONFIG_DISCONTIGMEM */
 379
 380 /*
 381  * paging_init() sets up the page tables - note that the first 8MB are
 382  * already mapped by head.S.
 383  *
 384  * This routines also unmaps the page at virtual kernel address 0, so
 385  * that we can trap those pesky NULL-reference errors in the kernel.
 386  */
 387 void __init paging_init(void)
 388 {
 389         pagetable_init();
 390
 391         load_cr3(swapper_pg_dir);
 392
 393 #ifdef CONFIG_X86_PAE
 394         /*
 395          * We will bail out later - printk doesn't work right now so
 396          * the user would just see a hanging kernel.
 397          */
 398         if (cpu_has_pae)
 399                 set_in_cr4(X86_CR4_PAE);
 400 #endif
 401         __flush_tlb_all();
 402         /*
 403          * Subtle. SMP is doing it's boot stuff late (because it has to
 404          * fork idle threads) - but it also needs low mappings for the
 405          * protected-mode entry to work. We zap these entries only after
 406          * the WP-bit has been tested.
 407          */
 408 #ifndef CONFIG_SMP
 409         zap_low_mappings();
 410 #endif
 411         kmap_init();
 412         zone_sizes_init();
 413 }
 414
 415 /*
 416  * Test if the WP bit works in supervisor mode. It isn't supported on 386's
 417  * and also on some strange 486's (NexGen etc.). All 586+'s are OK. This
 418  * used to involve black magic jumps to work around some nasty CPU bugs,
 419  * but fortunately the switch to using exceptions got rid of all that.
 420  */
 421
 422 void __init test_wp_bit(void)
 423 {
 424         printk("Checking if this processor honours the WP bit even in supervisor mode... ");
 425
 426         /* Any page-aligned address will do, the test is non-destructive */
 427         __set_fixmap(FIX_WP_TEST, __pa(&swapper_pg_dir), PAGE_READONLY);
 428         boot_cpu_data.wp_works_ok = do_test_wp_bit();
 429         clear_fixmap(FIX_WP_TEST);
 430
 431         if (!boot_cpu_data.wp_works_ok) {
 432                 printk("No.\n");
 433 #ifdef CONFIG_X86_WP_WORKS_OK
 434                 panic("This kernel doesn't support CPU's with broken WP. Recompile it for a 386!");
 435 #endif
 436         } else {
 437                 printk("Ok.\n");
 438         }
 439 }
 440
 441 #ifndef CONFIG_DISCONTIGMEM
 442 static void __init set_max_mapnr_init(void)
 443 {
 444 #ifdef CONFIG_HIGHMEM
 445         highmem_start_page = pfn_to_page(highstart_pfn);
 446         max_mapnr = num_physpages = highend_pfn;
 447 #else
 448         max_mapnr = num_physpages = max_low_pfn;
 449 #endif
 450 }
 451 #define __free_all_bootmem() free_all_bootmem()
 452 #else
 453 #define __free_all_bootmem() free_all_bootmem_node(NODE_DATA(0))
 454 extern void set_max_mapnr_init(void);
 455 #endif /* !CONFIG_DISCONTIGMEM */
 456
 457 static struct kcore_list kcore_mem, kcore_vmalloc;
 458
 459 void __init mem_init(void)
 460 {
 461         extern int ppro_with_ram_bug(void);
 462         int codesize, reservedpages, datasize, initsize;
 463         int tmp;
 464         int bad_ppro;
 465
 466 #ifndef CONFIG_DISCONTIGMEM
 467         if (!mem_map)
 468                 BUG();
 469 #endif
 470
 471         bad_ppro = ppro_with_ram_bug();
 472
 473 #ifdef CONFIG_HIGHMEM
 474         /* check that fixmap and pkmap do not overlap */
 475         if (PKMAP_BASE+LAST_PKMAP*PAGE_SIZE >= FIXADDR_START) {
 476                 printk(KERN_ERR "fixmap and kmap areas overlap - this will crash\n");
 477                 printk(KERN_ERR "pkstart: %lxh pkend: %lxh fixstart %lxh\n",
 478                                 PKMAP_BASE, PKMAP_BASE+LAST_PKMAP*PAGE_SIZE, FIXADDR_START);
 479                 BUG();
 480         }
 481 #endif
 482
 483         set_max_mapnr_init();
 484
 485 #ifdef CONFIG_HIGHMEM
 486         high_memory = (void *) __va(highstart_pfn * PAGE_SIZE);
 487 #else
 488         high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);
 489 #endif
 490
 491         /* this will put all low memory onto the freelists */
 492         totalram_pages += __free_all_bootmem();
 493
 494         reservedpages = 0;
 495         for (tmp = 0; tmp < max_low_pfn; tmp++)
 496                 /*
 497                  * Only count reserved RAM pages
 498                  */
 499                 if (page_is_ram(tmp) && PageReserved(pfn_to_page(tmp)))
 500                         reservedpages++;
 501
 502         set_highmem_pages_init(bad_ppro);
 503
 504         codesize =  (unsigned long) &_etext - (unsigned long) &_text;
 505         datasize =  (unsigned long) &_edata - (unsigned long) &_etext;
 506         initsize =  (unsigned long) &__init_end - (unsigned long) &__init_begin;
 507
 508         kclist_add(&kcore_mem, __va(0), max_low_pfn << PAGE_SHIFT);
 509         kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
 510                    VMALLOC_END-VMALLOC_START);
 511
 512         printk(KERN_INFO "Memory: %luk/%luk available (%dk kernel code, %dk reserved, %dk data, %dk init, %ldk highmem)\n",
 513                 (unsigned long) nr_free_pages() << (PAGE_SHIFT-10),
 514                 num_physpages << (PAGE_SHIFT-10),
 515                 codesize >> 10,
 516                 reservedpages << (PAGE_SHIFT-10),
 517                 datasize >> 10,
 518                 initsize >> 10,
 519                 (unsigned long) (totalhigh_pages << (PAGE_SHIFT-10))
 520                );
 521
 522 #ifdef CONFIG_X86_PAE
 523         if (!cpu_has_pae)
 524                 panic("cannot execute a PAE-enabled kernel on a PAE-less CPU!");
 525 #endif
 526         if (boot_cpu_data.wp_works_ok < 0)
 527                 test_wp_bit();
 528
 529         entry_trampoline_setup();
 530         default_ldt_page = virt_to_page(default_ldt);
 531         load_LDT(&init_mm.context);
 532 }
 533
 534 kmem_cache_t *pgd_cache, *pmd_cache, *kpmd_cache;
 535
 536 void __init pgtable_cache_init(void)
 537 {
 538         void (*ctor)(void *, kmem_cache_t *, unsigned long);
 539         void (*dtor)(void *, kmem_cache_t *, unsigned long);
 540
 541         if (PTRS_PER_PMD > 1) {
 542                 pmd_cache = kmem_cache_create("pmd",
 543                                         PTRS_PER_PMD*sizeof(pmd_t),
 544                                         PTRS_PER_PMD*sizeof(pmd_t),
 545                                         0,
 546                                         pmd_ctor,
 547                                         NULL);
 548                 if (!pmd_cache)
 549                         panic("pgtable_cache_init(): cannot create pmd cache");
 550
 551                 if (TASK_SIZE > PAGE_OFFSET) {
 552                         kpmd_cache = kmem_cache_create("kpmd",
 553                                         PTRS_PER_PMD*sizeof(pmd_t),
 554                                         PTRS_PER_PMD*sizeof(pmd_t),
 555                                         0,
 556                                         kpmd_ctor,
 557                                         NULL);
 558                         if (!kpmd_cache)
 559                                 panic("pgtable_cache_init(): "
 560                                                 "cannot create kpmd cache");
 561                 }
 562         }
 563
 564         if (PTRS_PER_PMD == 1 || TASK_SIZE <= PAGE_OFFSET)
 565                 ctor = pgd_ctor;
 566         else
 567                 ctor = NULL;
 568
 569         if (PTRS_PER_PMD == 1 && TASK_SIZE <= PAGE_OFFSET)
 570                 dtor = pgd_dtor;
 571         else
 572                 dtor = NULL;
 573
 574         pgd_cache = kmem_cache_create("pgd",
 575                                 PTRS_PER_PGD*sizeof(pgd_t),
 576                                 PTRS_PER_PGD*sizeof(pgd_t),
 577                                 0,
 578                                 ctor,
 579                                 dtor);
 580         if (!pgd_cache)
 581                 panic("pgtable_cache_init(): Cannot create pgd cache");
 582 }
 583
 584 /*
 585  * This function cannot be __init, since exceptions don't work in that
 586  * section.  Put this after the callers, so that it cannot be inlined.
 587  */
 588 static int noinline do_test_wp_bit(void)
 589 {
 590         char tmp_reg;
 591         int flag;
 592
 593         __asm__ __volatile__(
 594                 "       movb %0,%1      \n"
 595                 "1:     movb %1,%0      \n"
 596                 "       xorl %2,%2      \n"
 597                 "2:                     \n"
 598                 ".section __ex_table,\"a\"\n"
 599                 "       .align 4        \n"
 600                 "       .long 1b,2b     \n"
 601                 ".previous              \n"
 602                 :"=m" (*(char *)fix_to_virt(FIX_WP_TEST)),
 603                  "=q" (tmp_reg),
 604                  "=r" (flag)
 605                 :"2" (1)
 606                 :"memory");
 607
 608         return flag;
 609 }
 610
 611 void free_initmem(void)
 612 {
 613         unsigned long addr;
 614
 615         addr = (unsigned long)(&__init_begin);
 616         for (; addr < (unsigned long)(&__init_end); addr += PAGE_SIZE) {
 617                 ClearPageReserved(virt_to_page(addr));
 618                 set_page_count(virt_to_page(addr), 1);
 619                 free_page(addr);
 620                 totalram_pages++;
 621         }
 622         printk (KERN_INFO "Freeing unused kernel memory: %dk freed\n", (__init_end - __init_begin) >> 10);
 623 }
 624
 625 #ifdef CONFIG_BLK_DEV_INITRD
 626 void free_initrd_mem(unsigned long start, unsigned long end)
 627 {
 628         if (start < end)
 629                 printk (KERN_INFO "Freeing initrd memory: %ldk freed\n", (end - start) >> 10);
 630         for (; start < end; start += PAGE_SIZE) {
 631                 ClearPageReserved(virt_to_page(start));
 632                 set_page_count(virt_to_page(start), 1);
 633                 free_page(start);
 634                 totalram_pages++;
 635         }
 636 }
 637 #endif