kernel/fork.c

   1 /*
   2  *  linux/kernel/fork.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 /*
   8  *  'fork.c' contains the help-routines for the 'fork' system call
   9  * (see also entry.S and others).
  10  * Fork is rather simple, once you get the hang of it, but the memory
  11  * management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
  12  */
  13
  14 #include <linux/config.h>
  15 #include <linux/slab.h>
  16 #include <linux/init.h>
  17 #include <linux/unistd.h>
  18 #include <linux/smp_lock.h>
  19 #include <linux/module.h>
  20 #include <linux/vmalloc.h>
  21 #include <linux/completion.h>
  22 #include <linux/namespace.h>
  23 #include <linux/personality.h>
  24 #include <linux/mempolicy.h>
  25 #include <linux/sem.h>
  26 #include <linux/file.h>
  27 #include <linux/key.h>
  28 #include <linux/binfmts.h>
  29 #include <linux/mman.h>
  30 #include <linux/fs.h>
  31 #include <linux/cpu.h>
  32 #include <linux/cpuset.h>
  33 #include <linux/security.h>
  34 #include <linux/swap.h>
  35 #include <linux/syscalls.h>
  36 #include <linux/jiffies.h>
  37 #include <linux/futex.h>
  38 #include <linux/rcupdate.h>
  39 #include <linux/ptrace.h>
  40 #include <linux/mount.h>
  41 #include <linux/audit.h>
  42 #include <linux/profile.h>
  43 #include <linux/rmap.h>
  44 #include <linux/acct.h>
  45
  46 #include <asm/pgtable.h>
  47 #include <asm/pgalloc.h>
  48 #include <asm/uaccess.h>
  49 #include <asm/mmu_context.h>
  50 #include <asm/cacheflush.h>
  51 #include <asm/tlbflush.h>
  52
  53 /*
  54  * Protected counters by write_lock_irq(&tasklist_lock)
  55  */
  56 unsigned long total_forks;      /* Handle normal Linux uptimes. */
  57 int nr_threads;                 /* The idle threads do not count.. */
  58
  59 int max_threads;                /* tunable limit on nr_threads */
  60
  61 DEFINE_PER_CPU(unsigned long, process_counts) = 0;
  62
  63  __cacheline_aligned DEFINE_RWLOCK(tasklist_lock);  /* outer */
  64
  65 EXPORT_SYMBOL(tasklist_lock);
  66
  67 int nr_processes(void)
  68 {
  69         int cpu;
  70         int total = 0;
  71
  72         for_each_online_cpu(cpu)
  73                 total += per_cpu(process_counts, cpu);
  74
  75         return total;
  76 }
  77
  78 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
  79 # define alloc_task_struct()    kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
  80 # define free_task_struct(tsk)  kmem_cache_free(task_struct_cachep, (tsk))
  81 static kmem_cache_t *task_struct_cachep;
  82 #endif
  83
  84 /* SLAB cache for signal_struct structures (tsk->signal) */
  85 kmem_cache_t *signal_cachep;
  86
  87 /* SLAB cache for sighand_struct structures (tsk->sighand) */
  88 kmem_cache_t *sighand_cachep;
  89
  90 /* SLAB cache for files_struct structures (tsk->files) */
  91 kmem_cache_t *files_cachep;
  92
  93 /* SLAB cache for fs_struct structures (tsk->fs) */
  94 kmem_cache_t *fs_cachep;
  95
  96 /* SLAB cache for vm_area_struct structures */
  97 kmem_cache_t *vm_area_cachep;
  98
  99 /* SLAB cache for mm_struct structures (tsk->mm) */
 100 static kmem_cache_t *mm_cachep;
 101
 102 void free_task(struct task_struct *tsk)
 103 {
 104         free_thread_info(tsk->thread_info);
 105         free_task_struct(tsk);
 106 }
 107 EXPORT_SYMBOL(free_task);
 108
 109 void __put_task_struct(struct task_struct *tsk)
 110 {
 111         WARN_ON(!(tsk->exit_state & (EXIT_DEAD | EXIT_ZOMBIE)));
 112         WARN_ON(atomic_read(&tsk->usage));
 113         WARN_ON(tsk == current);
 114
 115         if (unlikely(tsk->audit_context))
 116                 audit_free(tsk);
 117         security_task_free(tsk);
 118         free_uid(tsk->user);
 119         put_group_info(tsk->group_info);
 120
 121         if (!profile_handoff_task(tsk))
 122                 free_task(tsk);
 123 }
 124
 125 void __init fork_init(unsigned long mempages)
 126 {
 127 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
 128 #ifndef ARCH_MIN_TASKALIGN
 129 #define ARCH_MIN_TASKALIGN      L1_CACHE_BYTES
 130 #endif
 131         /* create a slab on which task_structs can be allocated */
 132         task_struct_cachep =
 133                 kmem_cache_create("task_struct", sizeof(struct task_struct),
 134                         ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL, NULL);
 135 #endif
 136
 137         /*
 138          * The default maximum number of threads is set to a safe
 139          * value: the thread structures can take up at most half
 140          * of memory.
 141          */
 142         max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
 143
 144         /*
 145          * we need to allow at least 20 threads to boot a system
 146          */
 147         if(max_threads < 20)
 148                 max_threads = 20;
 149
 150         init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
 151         init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
 152         init_task.signal->rlim[RLIMIT_SIGPENDING] =
 153                 init_task.signal->rlim[RLIMIT_NPROC];
 154 }
 155
 156 static struct task_struct *dup_task_struct(struct task_struct *orig)
 157 {
 158         struct task_struct *tsk;
 159         struct thread_info *ti;
 160
 161         prepare_to_copy(orig);
 162
 163         tsk = alloc_task_struct();
 164         if (!tsk)
 165                 return NULL;
 166
 167         ti = alloc_thread_info(tsk);
 168         if (!ti) {
 169                 free_task_struct(tsk);
 170                 return NULL;
 171         }
 172
 173         *ti = *orig->thread_info;
 174         *tsk = *orig;
 175         tsk->thread_info = ti;
 176         ti->task = tsk;
 177
 178         /* One for us, one for whoever does the "release_task()" (usually parent) */
 179         atomic_set(&tsk->usage,2);
 180         atomic_set(&tsk->fs_excl, 0);
 181         return tsk;
 182 }
 183
 184 #ifdef CONFIG_MMU
 185 static inline int dup_mmap(struct mm_struct * mm, struct mm_struct * oldmm)
 186 {
 187         struct vm_area_struct * mpnt, *tmp, **pprev;
 188         struct rb_node **rb_link, *rb_parent;
 189         int retval;
 190         unsigned long charge;
 191         struct mempolicy *pol;
 192
 193         down_write(&oldmm->mmap_sem);
 194         flush_cache_mm(current->mm);
 195         mm->locked_vm = 0;
 196         mm->mmap = NULL;
 197         mm->mmap_cache = NULL;
 198         mm->free_area_cache = oldmm->mmap_base;
 199         mm->cached_hole_size = ~0UL;
 200         mm->map_count = 0;
 201         set_mm_counter(mm, rss, 0);
 202         set_mm_counter(mm, anon_rss, 0);
 203         cpus_clear(mm->cpu_vm_mask);
 204         mm->mm_rb = RB_ROOT;
 205         rb_link = &mm->mm_rb.rb_node;
 206         rb_parent = NULL;
 207         pprev = &mm->mmap;
 208
 209         for (mpnt = current->mm->mmap ; mpnt ; mpnt = mpnt->vm_next) {
 210                 struct file *file;
 211
 212                 if (mpnt->vm_flags & VM_DONTCOPY) {
 213                         long pages = vma_pages(mpnt);
 214                         mm->total_vm -= pages;
 215                         __vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
 216                                                                 -pages);
 217                         continue;
 218                 }
 219                 charge = 0;
 220                 if (mpnt->vm_flags & VM_ACCOUNT) {
 221                         unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
 222                         if (security_vm_enough_memory(len))
 223                                 goto fail_nomem;
 224                         charge = len;
 225                 }
 226                 tmp = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
 227                 if (!tmp)
 228                         goto fail_nomem;
 229                 *tmp = *mpnt;
 230                 pol = mpol_copy(vma_policy(mpnt));
 231                 retval = PTR_ERR(pol);
 232                 if (IS_ERR(pol))
 233                         goto fail_nomem_policy;
 234                 vma_set_policy(tmp, pol);
 235                 tmp->vm_flags &= ~VM_LOCKED;
 236                 tmp->vm_mm = mm;
 237                 tmp->vm_next = NULL;
 238                 anon_vma_link(tmp);
 239                 file = tmp->vm_file;
 240                 if (file) {
 241                         struct inode *inode = file->f_dentry->d_inode;
 242                         get_file(file);
 243                         if (tmp->vm_flags & VM_DENYWRITE)
 244                                 atomic_dec(&inode->i_writecount);
 245
 246                         /* insert tmp into the share list, just after mpnt */
 247                         spin_lock(&file->f_mapping->i_mmap_lock);
 248                         tmp->vm_truncate_count = mpnt->vm_truncate_count;
 249                         flush_dcache_mmap_lock(file->f_mapping);
 250                         vma_prio_tree_add(tmp, mpnt);
 251                         flush_dcache_mmap_unlock(file->f_mapping);
 252                         spin_unlock(&file->f_mapping->i_mmap_lock);
 253                 }
 254
 255                 /*
 256                  * Link in the new vma and copy the page table entries:
 257                  * link in first so that swapoff can see swap entries.
 258                  * Note that, exceptionally, here the vma is inserted
 259                  * without holding mm->mmap_sem.
 260                  */
 261                 spin_lock(&mm->page_table_lock);
 262                 *pprev = tmp;
 263                 pprev = &tmp->vm_next;
 264
 265                 __vma_link_rb(mm, tmp, rb_link, rb_parent);
 266                 rb_link = &tmp->vm_rb.rb_right;
 267                 rb_parent = &tmp->vm_rb;
 268
 269                 mm->map_count++;
 270                 retval = copy_page_range(mm, current->mm, tmp);
 271                 spin_unlock(&mm->page_table_lock);
 272
 273                 if (tmp->vm_ops && tmp->vm_ops->open)
 274                         tmp->vm_ops->open(tmp);
 275
 276                 if (retval)
 277                         goto out;
 278         }
 279         retval = 0;
 280
 281 out:
 282         flush_tlb_mm(current->mm);
 283         up_write(&oldmm->mmap_sem);
 284         return retval;
 285 fail_nomem_policy:
 286         kmem_cache_free(vm_area_cachep, tmp);
 287 fail_nomem:
 288         retval = -ENOMEM;
 289         vm_unacct_memory(charge);
 290         goto out;
 291 }
 292
 293 static inline int mm_alloc_pgd(struct mm_struct * mm)
 294 {
 295         mm->pgd = pgd_alloc(mm);
 296         if (unlikely(!mm->pgd))
 297                 return -ENOMEM;
 298         return 0;
 299 }
 300
 301 static inline void mm_free_pgd(struct mm_struct * mm)
 302 {
 303         pgd_free(mm->pgd);
 304 }
 305 #else
 306 #define dup_mmap(mm, oldmm)     (0)
 307 #define mm_alloc_pgd(mm)        (0)
 308 #define mm_free_pgd(mm)
 309 #endif /* CONFIG_MMU */
 310
 311  __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
 312
 313 #define allocate_mm()   (kmem_cache_alloc(mm_cachep, SLAB_KERNEL))
 314 #define free_mm(mm)     (kmem_cache_free(mm_cachep, (mm)))
 315
 316 #include <linux/init_task.h>
 317
 318 static struct mm_struct * mm_init(struct mm_struct * mm)
 319 {
 320         atomic_set(&mm->mm_users, 1);
 321         atomic_set(&mm->mm_count, 1);
 322         init_rwsem(&mm->mmap_sem);
 323         INIT_LIST_HEAD(&mm->mmlist);
 324         mm->core_waiters = 0;
 325         mm->nr_ptes = 0;
 326         spin_lock_init(&mm->page_table_lock);
 327         rwlock_init(&mm->ioctx_list_lock);
 328         mm->ioctx_list = NULL;
 329         mm->default_kioctx = (struct kioctx)INIT_KIOCTX(mm->default_kioctx, *mm);
 330         mm->free_area_cache = TASK_UNMAPPED_BASE;
 331         mm->cached_hole_size = ~0UL;
 332
 333         if (likely(!mm_alloc_pgd(mm))) {
 334                 mm->def_flags = 0;
 335                 return mm;
 336         }
 337         free_mm(mm);
 338         return NULL;
 339 }
 340
 341 /*
 342  * Allocate and initialize an mm_struct.
 343  */
 344 struct mm_struct * mm_alloc(void)
 345 {
 346         struct mm_struct * mm;
 347
 348         mm = allocate_mm();
 349         if (mm) {
 350                 memset(mm, 0, sizeof(*mm));
 351                 mm = mm_init(mm);
 352         }
 353         return mm;
 354 }
 355
 356 /*
 357  * Called when the last reference to the mm
 358  * is dropped: either by a lazy thread or by
 359  * mmput. Free the page directory and the mm.
 360  */
 361 void fastcall __mmdrop(struct mm_struct *mm)
 362 {
 363         BUG_ON(mm == &init_mm);
 364         mm_free_pgd(mm);
 365         destroy_context(mm);
 366         free_mm(mm);
 367 }
 368
 369 /*
 370  * Decrement the use count and release all resources for an mm.
 371  */
 372 void mmput(struct mm_struct *mm)
 373 {
 374         if (atomic_dec_and_test(&mm->mm_users)) {
 375                 exit_aio(mm);
 376                 exit_mmap(mm);
 377                 if (!list_empty(&mm->mmlist)) {
 378                         spin_lock(&mmlist_lock);
 379                         list_del(&mm->mmlist);
 380                         spin_unlock(&mmlist_lock);
 381                 }
 382                 put_swap_token(mm);
 383                 mmdrop(mm);
 384         }
 385 }
 386 EXPORT_SYMBOL_GPL(mmput);
 387
 388 /**
 389  * get_task_mm - acquire a reference to the task's mm
 390  *
 391  * Returns %NULL if the task has no mm.  Checks PF_BORROWED_MM (meaning
 392  * this kernel workthread has transiently adopted a user mm with use_mm,
 393  * to do its AIO) is not set and if so returns a reference to it, after
 394  * bumping up the use count.  User must release the mm via mmput()
 395  * after use.  Typically used by /proc and ptrace.
 396  */
 397 struct mm_struct *get_task_mm(struct task_struct *task)
 398 {
 399         struct mm_struct *mm;
 400
 401         task_lock(task);
 402         mm = task->mm;
 403         if (mm) {
 404                 if (task->flags & PF_BORROWED_MM)
 405                         mm = NULL;
 406                 else
 407                         atomic_inc(&mm->mm_users);
 408         }
 409         task_unlock(task);
 410         return mm;
 411 }
 412 EXPORT_SYMBOL_GPL(get_task_mm);
 413
 414 /* Please note the differences between mmput and mm_release.
 415  * mmput is called whenever we stop holding onto a mm_struct,
 416  * error success whatever.
 417  *
 418  * mm_release is called after a mm_struct has been removed
 419  * from the current process.
 420  *
 421  * This difference is important for error handling, when we
 422  * only half set up a mm_struct for a new process and need to restore
 423  * the old one.  Because we mmput the new mm_struct before
 424  * restoring the old one. . .
 425  * Eric Biederman 10 January 1998
 426  */
 427 void mm_release(struct task_struct *tsk, struct mm_struct *mm)
 428 {
 429         struct completion *vfork_done = tsk->vfork_done;
 430
 431         /* Get rid of any cached register state */
 432         deactivate_mm(tsk, mm);
 433
 434         /* notify parent sleeping on vfork() */
 435         if (vfork_done) {
 436                 tsk->vfork_done = NULL;
 437                 complete(vfork_done);
 438         }
 439         if (tsk->clear_child_tid && atomic_read(&mm->mm_users) > 1) {
 440                 u32 __user * tidptr = tsk->clear_child_tid;
 441                 tsk->clear_child_tid = NULL;
 442
 443                 /*
 444                  * We don't check the error code - if userspace has
 445                  * not set up a proper pointer then tough luck.
 446                  */
 447                 put_user(0, tidptr);
 448                 sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0);
 449         }
 450 }
 451
 452 static int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
 453 {
 454         struct mm_struct * mm, *oldmm;
 455         int retval;
 456
 457         tsk->min_flt = tsk->maj_flt = 0;
 458         tsk->nvcsw = tsk->nivcsw = 0;
 459
 460         tsk->mm = NULL;
 461         tsk->active_mm = NULL;
 462
 463         /*
 464          * Are we cloning a kernel thread?
 465          *
 466          * We need to steal a active VM for that..
 467          */
 468         oldmm = current->mm;
 469         if (!oldmm)
 470                 return 0;
 471
 472         if (clone_flags & CLONE_VM) {
 473                 atomic_inc(&oldmm->mm_users);
 474                 mm = oldmm;
 475                 /*
 476                  * There are cases where the PTL is held to ensure no
 477                  * new threads start up in user mode using an mm, which
 478                  * allows optimizing out ipis; the tlb_gather_mmu code
 479                  * is an example.
 480                  */
 481                 spin_unlock_wait(&oldmm->page_table_lock);
 482                 goto good_mm;
 483         }
 484
 485         retval = -ENOMEM;
 486         mm = allocate_mm();
 487         if (!mm)
 488                 goto fail_nomem;
 489
 490         /* Copy the current MM stuff.. */
 491         memcpy(mm, oldmm, sizeof(*mm));
 492         if (!mm_init(mm))
 493                 goto fail_nomem;
 494
 495         if (init_new_context(tsk,mm))
 496                 goto fail_nocontext;
 497
 498         retval = dup_mmap(mm, oldmm);
 499         if (retval)
 500                 goto free_pt;
 501
 502         mm->hiwater_rss = get_mm_counter(mm,rss);
 503         mm->hiwater_vm = mm->total_vm;
 504
 505 good_mm:
 506         tsk->mm = mm;
 507         tsk->active_mm = mm;
 508         return 0;
 509
 510 free_pt:
 511         mmput(mm);
 512 fail_nomem:
 513         return retval;
 514
 515 fail_nocontext:
 516         /*
 517          * If init_new_context() failed, we cannot use mmput() to free the mm
 518          * because it calls destroy_context()
 519          */
 520         mm_free_pgd(mm);
 521         free_mm(mm);
 522         return retval;
 523 }
 524
 525 static inline struct fs_struct *__copy_fs_struct(struct fs_struct *old)
 526 {
 527         struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
 528         /* We don't need to lock fs - think why ;-) */
 529         if (fs) {
 530                 atomic_set(&fs->count, 1);
 531                 rwlock_init(&fs->lock);
 532                 fs->umask = old->umask;
 533                 read_lock(&old->lock);
 534                 fs->rootmnt = mntget(old->rootmnt);
 535                 fs->root = dget(old->root);
 536                 fs->pwdmnt = mntget(old->pwdmnt);
 537                 fs->pwd = dget(old->pwd);
 538                 if (old->altroot) {
 539                         fs->altrootmnt = mntget(old->altrootmnt);
 540                         fs->altroot = dget(old->altroot);
 541                 } else {
 542                         fs->altrootmnt = NULL;
 543                         fs->altroot = NULL;
 544                 }
 545                 read_unlock(&old->lock);
 546         }
 547         return fs;
 548 }
 549
 550 struct fs_struct *copy_fs_struct(struct fs_struct *old)
 551 {
 552         return __copy_fs_struct(old);
 553 }
 554
 555 EXPORT_SYMBOL_GPL(copy_fs_struct);
 556
 557 static inline int copy_fs(unsigned long clone_flags, struct task_struct * tsk)
 558 {
 559         if (clone_flags & CLONE_FS) {
 560                 atomic_inc(&current->fs->count);
 561                 return 0;
 562         }
 563         tsk->fs = __copy_fs_struct(current->fs);
 564         if (!tsk->fs)
 565                 return -ENOMEM;
 566         return 0;
 567 }
 568
 569 static int count_open_files(struct fdtable *fdt)
 570 {
 571         int size = fdt->max_fdset;
 572         int i;
 573
 574         /* Find the last open fd */
 575         for (i = size/(8*sizeof(long)); i > 0; ) {
 576                 if (fdt->open_fds->fds_bits[--i])
 577                         break;
 578         }
 579         i = (i+1) * 8 * sizeof(long);
 580         return i;
 581 }
 582
 583 static struct files_struct *alloc_files(void)
 584 {
 585         struct files_struct *newf;
 586         struct fdtable *fdt;
 587
 588         newf = kmem_cache_alloc(files_cachep, SLAB_KERNEL);
 589         if (!newf)
 590                 goto out;
 591
 592         atomic_set(&newf->count, 1);
 593
 594         spin_lock_init(&newf->file_lock);
 595         fdt = &newf->fdtab;
 596         fdt->next_fd = 0;
 597         fdt->max_fds = NR_OPEN_DEFAULT;
 598         fdt->max_fdset = __FD_SETSIZE;
 599         fdt->close_on_exec = &newf->close_on_exec_init;
 600         fdt->open_fds = &newf->open_fds_init;
 601         fdt->fd = &newf->fd_array[0];
 602         INIT_RCU_HEAD(&fdt->rcu);
 603         fdt->free_files = NULL;
 604         fdt->next = NULL;
 605         rcu_assign_pointer(newf->fdt, fdt);
 606 out:
 607         return newf;
 608 }
 609
 610 static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
 611 {
 612         struct files_struct *oldf, *newf;
 613         struct file **old_fds, **new_fds;
 614         int open_files, size, i, error = 0, expand;
 615         struct fdtable *old_fdt, *new_fdt;
 616
 617         /*
 618          * A background process may not have any files ...
 619          */
 620         oldf = current->files;
 621         if (!oldf)
 622                 goto out;
 623
 624         if (clone_flags & CLONE_FILES) {
 625                 atomic_inc(&oldf->count);
 626                 goto out;
 627         }
 628
 629         /*
 630          * Note: we may be using current for both targets (See exec.c)
 631          * This works because we cache current->files (old) as oldf. Don't
 632          * break this.
 633          */
 634         tsk->files = NULL;
 635         error = -ENOMEM;
 636         newf = alloc_files();
 637         if (!newf)
 638                 goto out;
 639
 640         spin_lock(&oldf->file_lock);
 641         old_fdt = files_fdtable(oldf);
 642         new_fdt = files_fdtable(newf);
 643         size = old_fdt->max_fdset;
 644         open_files = count_open_files(old_fdt);
 645         expand = 0;
 646
 647         /*
 648          * Check whether we need to allocate a larger fd array or fd set.
 649          * Note: we're not a clone task, so the open count won't  change.
 650          */
 651         if (open_files > new_fdt->max_fdset) {
 652                 new_fdt->max_fdset = 0;
 653                 expand = 1;
 654         }
 655         if (open_files > new_fdt->max_fds) {
 656                 new_fdt->max_fds = 0;
 657                 expand = 1;
 658         }
 659
 660         /* if the old fdset gets grown now, we'll only copy up to "size" fds */
 661         if (expand) {
 662                 spin_unlock(&oldf->file_lock);
 663                 spin_lock(&newf->file_lock);
 664                 error = expand_files(newf, open_files-1);
 665                 spin_unlock(&newf->file_lock);
 666                 if (error < 0)
 667                         goto out_release;
 668                 new_fdt = files_fdtable(newf);
 669                 /*
 670                  * Reacquire the oldf lock and a pointer to its fd table
 671                  * who knows it may have a new bigger fd table. We need
 672                  * the latest pointer.
 673                  */
 674                 spin_lock(&oldf->file_lock);
 675                 old_fdt = files_fdtable(oldf);
 676         }
 677
 678         old_fds = old_fdt->fd;
 679         new_fds = new_fdt->fd;
 680
 681         memcpy(new_fdt->open_fds->fds_bits, old_fdt->open_fds->fds_bits, open_files/8);
 682         memcpy(new_fdt->close_on_exec->fds_bits, old_fdt->close_on_exec->fds_bits, open_files/8);
 683
 684         for (i = open_files; i != 0; i--) {
 685                 struct file *f = *old_fds++;
 686                 if (f) {
 687                         get_file(f);
 688                 } else {
 689                         /*
 690                          * The fd may be claimed in the fd bitmap but not yet
 691                          * instantiated in the files array if a sibling thread
 692                          * is partway through open().  So make sure that this
 693                          * fd is available to the new process.
 694                          */
 695                         FD_CLR(open_files - i, new_fdt->open_fds);
 696                 }
 697                 rcu_assign_pointer(*new_fds++, f);
 698         }
 699         spin_unlock(&oldf->file_lock);
 700
 701         /* compute the remainder to be cleared */
 702         size = (new_fdt->max_fds - open_files) * sizeof(struct file *);
 703
 704         /* This is long word aligned thus could use a optimized version */
 705         memset(new_fds, 0, size);
 706
 707         if (new_fdt->max_fdset > open_files) {
 708                 int left = (new_fdt->max_fdset-open_files)/8;
 709                 int start = open_files / (8 * sizeof(unsigned long));
 710
 711                 memset(&new_fdt->open_fds->fds_bits[start], 0, left);
 712                 memset(&new_fdt->close_on_exec->fds_bits[start], 0, left);
 713         }
 714
 715         tsk->files = newf;
 716         error = 0;
 717 out:
 718         return error;
 719
 720 out_release:
 721         free_fdset (new_fdt->close_on_exec, new_fdt->max_fdset);
 722         free_fdset (new_fdt->open_fds, new_fdt->max_fdset);
 723         free_fd_array(new_fdt->fd, new_fdt->max_fds);
 724         kmem_cache_free(files_cachep, newf);
 725         goto out;
 726 }
 727
 728 /*
 729  *      Helper to unshare the files of the current task.
 730  *      We don't want to expose copy_files internals to
 731  *      the exec layer of the kernel.
 732  */
 733
 734 int unshare_files(void)
 735 {
 736         struct files_struct *files  = current->files;
 737         int rc;
 738
 739         if(!files)
 740                 BUG();
 741
 742         /* This can race but the race causes us to copy when we don't
 743            need to and drop the copy */
 744         if(atomic_read(&files->count) == 1)
 745         {
 746                 atomic_inc(&files->count);
 747                 return 0;
 748         }
 749         rc = copy_files(0, current);
 750         if(rc)
 751                 current->files = files;
 752         return rc;
 753 }
 754
 755 EXPORT_SYMBOL(unshare_files);
 756
 757 static inline int copy_sighand(unsigned long clone_flags, struct task_struct * tsk)
 758 {
 759         struct sighand_struct *sig;
 760
 761         if (clone_flags & (CLONE_SIGHAND | CLONE_THREAD)) {
 762                 atomic_inc(&current->sighand->count);
 763                 return 0;
 764         }
 765         sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
 766         tsk->sighand = sig;
 767         if (!sig)
 768                 return -ENOMEM;
 769         spin_lock_init(&sig->siglock);
 770         atomic_set(&sig->count, 1);
 771         memcpy(sig->action, current->sighand->action, sizeof(sig->action));
 772         return 0;
 773 }
 774
 775 static inline int copy_signal(unsigned long clone_flags, struct task_struct * tsk)
 776 {
 777         struct signal_struct *sig;
 778         int ret;
 779
 780         if (clone_flags & CLONE_THREAD) {
 781                 atomic_inc(&current->signal->count);
 782                 atomic_inc(&current->signal->live);
 783                 return 0;
 784         }
 785         sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
 786         tsk->signal = sig;
 787         if (!sig)
 788                 return -ENOMEM;
 789
 790         ret = copy_thread_group_keys(tsk);
 791         if (ret < 0) {
 792                 kmem_cache_free(signal_cachep, sig);
 793                 return ret;
 794         }
 795
 796         atomic_set(&sig->count, 1);
 797         atomic_set(&sig->live, 1);
 798         init_waitqueue_head(&sig->wait_chldexit);
 799         sig->flags = 0;
 800         sig->group_exit_code = 0;
 801         sig->group_exit_task = NULL;
 802         sig->group_stop_count = 0;
 803         sig->curr_target = NULL;
 804         init_sigpending(&sig->shared_pending);
 805         INIT_LIST_HEAD(&sig->posix_timers);
 806
 807         sig->it_real_value = sig->it_real_incr = 0;
 808         sig->real_timer.function = it_real_fn;
 809         sig->real_timer.data = (unsigned long) tsk;
 810         init_timer(&sig->real_timer);
 811
 812         sig->it_virt_expires = cputime_zero;
 813         sig->it_virt_incr = cputime_zero;
 814         sig->it_prof_expires = cputime_zero;
 815         sig->it_prof_incr = cputime_zero;
 816
 817         sig->tty = current->signal->tty;
 818         sig->pgrp = process_group(current);
 819         sig->session = current->signal->session;
 820         sig->leader = 0;        /* session leadership doesn't inherit */
 821         sig->tty_old_pgrp = 0;
 822
 823         sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero;
 824         sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0;
 825         sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0;
 826         sig->sched_time = 0;
 827         INIT_LIST_HEAD(&sig->cpu_timers[0]);
 828         INIT_LIST_HEAD(&sig->cpu_timers[1]);
 829         INIT_LIST_HEAD(&sig->cpu_timers[2]);
 830
 831         task_lock(current->group_leader);
 832         memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
 833         task_unlock(current->group_leader);
 834
 835         if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
 836                 /*
 837                  * New sole thread in the process gets an expiry time
 838                  * of the whole CPU time limit.
 839                  */
 840                 tsk->it_prof_expires =
 841                         secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
 842         }
 843
 844         return 0;
 845 }
 846
 847 static inline void copy_flags(unsigned long clone_flags, struct task_struct *p)
 848 {
 849         unsigned long new_flags = p->flags;
 850
 851         new_flags &= ~(PF_SUPERPRIV | PF_NOFREEZE);
 852         new_flags |= PF_FORKNOEXEC;
 853         if (!(clone_flags & CLONE_PTRACE))
 854                 p->ptrace = 0;
 855         p->flags = new_flags;
 856 }
 857
 858 asmlinkage long sys_set_tid_address(int __user *tidptr)
 859 {
 860         current->clear_child_tid = tidptr;
 861
 862         return current->pid;
 863 }
 864
 865 /*
 866  * This creates a new process as a copy of the old one,
 867  * but does not actually start it yet.
 868  *
 869  * It copies the registers, and all the appropriate
 870  * parts of the process environment (as per the clone
 871  * flags). The actual kick-off is left to the caller.
 872  */
 873 static task_t *copy_process(unsigned long clone_flags,
 874                                  unsigned long stack_start,
 875                                  struct pt_regs *regs,
 876                                  unsigned long stack_size,
 877                                  int __user *parent_tidptr,
 878                                  int __user *child_tidptr,
 879                                  int pid)
 880 {
 881         int retval;
 882         struct task_struct *p = NULL;
 883
 884         if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
 885                 return ERR_PTR(-EINVAL);
 886
 887         /*
 888          * Thread groups must share signals as well, and detached threads
 889          * can only be started up within the thread group.
 890          */
 891         if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
 892                 return ERR_PTR(-EINVAL);
 893
 894         /*
 895          * Shared signal handlers imply shared VM. By way of the above,
 896          * thread groups also imply shared VM. Blocking this case allows
 897          * for various simplifications in other code.
 898          */
 899         if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
 900                 return ERR_PTR(-EINVAL);
 901
 902         retval = security_task_create(clone_flags);
 903         if (retval)
 904                 goto fork_out;
 905
 906         retval = -ENOMEM;
 907         p = dup_task_struct(current);
 908         if (!p)
 909                 goto fork_out;
 910
 911         retval = -EAGAIN;
 912         if (atomic_read(&p->user->processes) >=
 913                         p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
 914                 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
 915                                 p->user != &root_user)
 916                         goto bad_fork_free;
 917         }
 918
 919         atomic_inc(&p->user->__count);
 920         atomic_inc(&p->user->processes);
 921         get_group_info(p->group_info);
 922
 923         /*
 924          * If multiple threads are within copy_process(), then this check
 925          * triggers too late. This doesn't hurt, the check is only there
 926          * to stop root fork bombs.
 927          */
 928         if (nr_threads >= max_threads)
 929                 goto bad_fork_cleanup_count;
 930
 931         if (!try_module_get(p->thread_info->exec_domain->module))
 932                 goto bad_fork_cleanup_count;
 933
 934         if (p->binfmt && !try_module_get(p->binfmt->module))
 935                 goto bad_fork_cleanup_put_domain;
 936
 937         p->did_exec = 0;
 938         copy_flags(clone_flags, p);
 939         p->pid = pid;
 940         retval = -EFAULT;
 941         if (clone_flags & CLONE_PARENT_SETTID)
 942                 if (put_user(p->pid, parent_tidptr))
 943                         goto bad_fork_cleanup;
 944
 945         p->proc_dentry = NULL;
 946
 947         INIT_LIST_HEAD(&p->children);
 948         INIT_LIST_HEAD(&p->sibling);
 949         p->vfork_done = NULL;
 950         spin_lock_init(&p->alloc_lock);
 951         spin_lock_init(&p->proc_lock);
 952
 953         clear_tsk_thread_flag(p, TIF_SIGPENDING);
 954         init_sigpending(&p->pending);
 955
 956         p->utime = cputime_zero;
 957         p->stime = cputime_zero;
 958         p->sched_time = 0;
 959         p->rchar = 0;           /* I/O counter: bytes read */
 960         p->wchar = 0;           /* I/O counter: bytes written */
 961         p->syscr = 0;           /* I/O counter: read syscalls */
 962         p->syscw = 0;           /* I/O counter: write syscalls */
 963         acct_clear_integrals(p);
 964
 965         p->it_virt_expires = cputime_zero;
 966         p->it_prof_expires = cputime_zero;
 967         p->it_sched_expires = 0;
 968         INIT_LIST_HEAD(&p->cpu_timers[0]);
 969         INIT_LIST_HEAD(&p->cpu_timers[1]);
 970         INIT_LIST_HEAD(&p->cpu_timers[2]);
 971
 972         p->lock_depth = -1;             /* -1 = no lock */
 973         do_posix_clock_monotonic_gettime(&p->start_time);
 974         p->security = NULL;
 975         p->io_context = NULL;
 976         p->io_wait = NULL;
 977         p->audit_context = NULL;
 978 #ifdef CONFIG_NUMA
 979         p->mempolicy = mpol_copy(p->mempolicy);
 980         if (IS_ERR(p->mempolicy)) {
 981                 retval = PTR_ERR(p->mempolicy);
 982                 p->mempolicy = NULL;
 983                 goto bad_fork_cleanup;
 984         }
 985 #endif
 986
 987         p->tgid = p->pid;
 988         if (clone_flags & CLONE_THREAD)
 989                 p->tgid = current->tgid;
 990
 991         if ((retval = security_task_alloc(p)))
 992                 goto bad_fork_cleanup_policy;
 993         if ((retval = audit_alloc(p)))
 994                 goto bad_fork_cleanup_security;
 995         /* copy all the process information */
 996         if ((retval = copy_semundo(clone_flags, p)))
 997                 goto bad_fork_cleanup_audit;
 998         if ((retval = copy_files(clone_flags, p)))
 999                 goto bad_fork_cleanup_semundo;
1000         if ((retval = copy_fs(clone_flags, p)))
1001                 goto bad_fork_cleanup_files;
1002         if ((retval = copy_sighand(clone_flags, p)))
1003                 goto bad_fork_cleanup_fs;
1004         if ((retval = copy_signal(clone_flags, p)))
1005                 goto bad_fork_cleanup_sighand;
1006         if ((retval = copy_mm(clone_flags, p)))
1007                 goto bad_fork_cleanup_signal;
1008         if ((retval = copy_keys(clone_flags, p)))
1009                 goto bad_fork_cleanup_mm;
1010         if ((retval = copy_namespace(clone_flags, p)))
1011                 goto bad_fork_cleanup_keys;
1012         retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
1013         if (retval)
1014                 goto bad_fork_cleanup_namespace;
1015
1016         p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
1017         /*
1018          * Clear TID on mm_release()?
1019          */
1020         p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL;
1021
1022         /*
1023          * Syscall tracing should be turned off in the child regardless
1024          * of CLONE_PTRACE.
1025          */
1026         clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
1027 #ifdef TIF_SYSCALL_EMU
1028         clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
1029 #endif
1030
1031         /* Our parent execution domain becomes current domain
1032            These must match for thread signalling to apply */
1033
1034         p->parent_exec_id = p->self_exec_id;
1035
1036         /* ok, now we should be set up.. */
1037         p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
1038         p->pdeath_signal = 0;
1039         p->exit_state = 0;
1040
1041         /*
1042          * Ok, make it visible to the rest of the system.
1043          * We dont wake it up yet.
1044          */
1045         p->group_leader = p;
1046         INIT_LIST_HEAD(&p->ptrace_children);
1047         INIT_LIST_HEAD(&p->ptrace_list);
1048
1049         /* Perform scheduler related setup. Assign this task to a CPU. */
1050         sched_fork(p, clone_flags);
1051
1052         /* Need tasklist lock for parent etc handling! */
1053         write_lock_irq(&tasklist_lock);
1054
1055         /*
1056          * The task hasn't been attached yet, so its cpus_allowed mask will
1057          * not be changed, nor will its assigned CPU.
1058          *
1059          * The cpus_allowed mask of the parent may have changed after it was
1060          * copied first time - so re-copy it here, then check the child's CPU
1061          * to ensure it is on a valid CPU (and if not, just force it back to
1062          * parent's CPU). This avoids alot of nasty races.
1063          */
1064         p->cpus_allowed = current->cpus_allowed;
1065         if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed) ||
1066                         !cpu_online(task_cpu(p))))
1067                 set_task_cpu(p, smp_processor_id());
1068
1069         /*
1070          * Check for pending SIGKILL! The new thread should not be allowed
1071          * to slip out of an OOM kill. (or normal SIGKILL.)
1072          */
1073         if (sigismember(&current->pending.signal, SIGKILL)) {
1074                 write_unlock_irq(&tasklist_lock);
1075                 retval = -EINTR;
1076                 goto bad_fork_cleanup_namespace;
1077         }
1078
1079         /* CLONE_PARENT re-uses the old parent */
1080         if (clone_flags & (CLONE_PARENT|CLONE_THREAD))
1081                 p->real_parent = current->real_parent;
1082         else
1083                 p->real_parent = current;
1084         p->parent = p->real_parent;
1085
1086         if (clone_flags & CLONE_THREAD) {
1087                 spin_lock(&current->sighand->siglock);
1088                 /*
1089                  * Important: if an exit-all has been started then
1090                  * do not create this new thread - the whole thread
1091                  * group is supposed to exit anyway.
1092                  */
1093                 if (current->signal->flags & SIGNAL_GROUP_EXIT) {
1094                         spin_unlock(&current->sighand->siglock);
1095                         write_unlock_irq(&tasklist_lock);
1096                         retval = -EAGAIN;
1097                         goto bad_fork_cleanup_namespace;
1098                 }
1099                 p->group_leader = current->group_leader;
1100
1101                 if (current->signal->group_stop_count > 0) {
1102                         /*
1103                          * There is an all-stop in progress for the group.
1104                          * We ourselves will stop as soon as we check signals.
1105                          * Make the new thread part of that group stop too.
1106                          */
1107                         current->signal->group_stop_count++;
1108                         set_tsk_thread_flag(p, TIF_SIGPENDING);
1109                 }
1110
1111                 if (!cputime_eq(current->signal->it_virt_expires,
1112                                 cputime_zero) ||
1113                     !cputime_eq(current->signal->it_prof_expires,
1114                                 cputime_zero) ||
1115                     current->signal->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY ||
1116                     !list_empty(&current->signal->cpu_timers[0]) ||
1117                     !list_empty(&current->signal->cpu_timers[1]) ||
1118                     !list_empty(&current->signal->cpu_timers[2])) {
1119                         /*
1120                          * Have child wake up on its first tick to check
1121                          * for process CPU timers.
1122                          */
1123                         p->it_prof_expires = jiffies_to_cputime(1);
1124                 }
1125
1126                 spin_unlock(&current->sighand->siglock);
1127         }
1128
1129         /*
1130          * inherit ioprio
1131          */
1132         p->ioprio = current->ioprio;
1133
1134         SET_LINKS(p);
1135         if (unlikely(p->ptrace & PT_PTRACED))
1136                 __ptrace_link(p, current->parent);
1137
1138         cpuset_fork(p);
1139
1140         attach_pid(p, PIDTYPE_PID, p->pid);
1141         attach_pid(p, PIDTYPE_TGID, p->tgid);
1142         if (thread_group_leader(p)) {
1143                 attach_pid(p, PIDTYPE_PGID, process_group(p));
1144                 attach_pid(p, PIDTYPE_SID, p->signal->session);
1145                 if (p->pid)
1146                         __get_cpu_var(process_counts)++;
1147         }
1148
1149         if (!current->signal->tty && p->signal->tty)
1150                 p->signal->tty = NULL;
1151
1152         nr_threads++;
1153         total_forks++;
1154         write_unlock_irq(&tasklist_lock);
1155         retval = 0;
1156
1157 fork_out:
1158         if (retval)
1159                 return ERR_PTR(retval);
1160         return p;
1161
1162 bad_fork_cleanup_namespace:
1163         exit_namespace(p);
1164 bad_fork_cleanup_keys:
1165         exit_keys(p);
1166 bad_fork_cleanup_mm:
1167         if (p->mm)
1168                 mmput(p->mm);
1169 bad_fork_cleanup_signal:
1170         exit_signal(p);
1171 bad_fork_cleanup_sighand:
1172         exit_sighand(p);
1173 bad_fork_cleanup_fs:
1174         exit_fs(p); /* blocking */
1175 bad_fork_cleanup_files:
1176         exit_files(p); /* blocking */
1177 bad_fork_cleanup_semundo:
1178         exit_sem(p);
1179 bad_fork_cleanup_audit:
1180         audit_free(p);
1181 bad_fork_cleanup_security:
1182         security_task_free(p);
1183 bad_fork_cleanup_policy:
1184 #ifdef CONFIG_NUMA
1185         mpol_free(p->mempolicy);
1186 #endif
1187 bad_fork_cleanup:
1188         if (p->binfmt)
1189                 module_put(p->binfmt->module);
1190 bad_fork_cleanup_put_domain:
1191         module_put(p->thread_info->exec_domain->module);
1192 bad_fork_cleanup_count:
1193         put_group_info(p->group_info);
1194         atomic_dec(&p->user->processes);
1195         free_uid(p->user);
1196 bad_fork_free:
1197         free_task(p);
1198         goto fork_out;
1199 }
1200
1201 struct pt_regs * __devinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
1202 {
1203         memset(regs, 0, sizeof(struct pt_regs));
1204         return regs;
1205 }
1206
1207 task_t * __devinit fork_idle(int cpu)
1208 {
1209         task_t *task;
1210         struct pt_regs regs;
1211
1212         task = copy_process(CLONE_VM, 0, idle_regs(&regs), 0, NULL, NULL, 0);
1213         if (!task)
1214                 return ERR_PTR(-ENOMEM);
1215         init_idle(task, cpu);
1216         unhash_process(task);
1217         return task;
1218 }
1219
1220 static inline int fork_traceflag (unsigned clone_flags)
1221 {
1222         if (clone_flags & CLONE_UNTRACED)
1223                 return 0;
1224         else if (clone_flags & CLONE_VFORK) {
1225                 if (current->ptrace & PT_TRACE_VFORK)
1226                         return PTRACE_EVENT_VFORK;
1227         } else if ((clone_flags & CSIGNAL) != SIGCHLD) {
1228                 if (current->ptrace & PT_TRACE_CLONE)
1229                         return PTRACE_EVENT_CLONE;
1230         } else if (current->ptrace & PT_TRACE_FORK)
1231                 return PTRACE_EVENT_FORK;
1232
1233         return 0;
1234 }
1235
1236 /*
1237  *  Ok, this is the main fork-routine.
1238  *
1239  * It copies the process, and if successful kick-starts
1240  * it and waits for it to finish using the VM if required.
1241  */
1242 long do_fork(unsigned long clone_flags,
1243               unsigned long stack_start,
1244               struct pt_regs *regs,
1245               unsigned long stack_size,
1246               int __user *parent_tidptr,
1247               int __user *child_tidptr)
1248 {
1249         struct task_struct *p;
1250         int trace = 0;
1251         long pid = alloc_pidmap();
1252
1253         if (pid < 0)
1254                 return -EAGAIN;
1255         if (unlikely(current->ptrace)) {
1256                 trace = fork_traceflag (clone_flags);
1257                 if (trace)
1258                         clone_flags |= CLONE_PTRACE;
1259         }
1260
1261         p = copy_process(clone_flags, stack_start, regs, stack_size, parent_tidptr, child_tidptr, pid);
1262         /*
1263          * Do this prior waking up the new thread - the thread pointer
1264          * might get invalid after that point, if the thread exits quickly.
1265          */
1266         if (!IS_ERR(p)) {
1267                 struct completion vfork;
1268
1269                 if (clone_flags & CLONE_VFORK) {
1270                         p->vfork_done = &vfork;
1271                         init_completion(&vfork);
1272                 }
1273
1274                 if ((p->ptrace & PT_PTRACED) || (clone_flags & CLONE_STOPPED)) {
1275                         /*
1276                          * We'll start up with an immediate SIGSTOP.
1277                          */
1278                         sigaddset(&p->pending.signal, SIGSTOP);
1279                         set_tsk_thread_flag(p, TIF_SIGPENDING);
1280                 }
1281
1282                 if (!(clone_flags & CLONE_STOPPED))
1283                         wake_up_new_task(p, clone_flags);
1284                 else
1285                         p->state = TASK_STOPPED;
1286
1287                 if (unlikely (trace)) {
1288                         current->ptrace_message = pid;
1289                         ptrace_notify ((trace << 8) | SIGTRAP);
1290                 }
1291
1292                 if (clone_flags & CLONE_VFORK) {
1293                         wait_for_completion(&vfork);
1294                         if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE))
1295                                 ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP);
1296                 }
1297         } else {
1298                 free_pidmap(pid);
1299                 pid = PTR_ERR(p);
1300         }
1301         return pid;
1302 }
1303
1304 void __init proc_caches_init(void)
1305 {
1306         sighand_cachep = kmem_cache_create("sighand_cache",
1307                         sizeof(struct sighand_struct), 0,
1308                         SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1309         signal_cachep = kmem_cache_create("signal_cache",
1310                         sizeof(struct signal_struct), 0,
1311                         SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1312         files_cachep = kmem_cache_create("files_cache",
1313                         sizeof(struct files_struct), 0,
1314                         SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1315         fs_cachep = kmem_cache_create("fs_cache",
1316                         sizeof(struct fs_struct), 0,
1317                         SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1318         vm_area_cachep = kmem_cache_create("vm_area_struct",
1319                         sizeof(struct vm_area_struct), 0,
1320                         SLAB_PANIC, NULL, NULL);
1321         mm_cachep = kmem_cache_create("mm_struct",
1322                         sizeof(struct mm_struct), 0,
1323                         SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1324 }