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/binfmts.h>
  28 #include <linux/mman.h>
  29 #include <linux/fs.h>
  30 #include <linux/cpu.h>
  31 #include <linux/security.h>
  32 #include <linux/syscalls.h>
  33 #include <linux/jiffies.h>
  34 #include <linux/futex.h>
  35 #include <linux/ptrace.h>
  36 #include <linux/mount.h>
  37 #include <linux/audit.h>
  38 #include <linux/rmap.h>
  39 #include <linux/ckrm.h>
  40 #include <linux/ckrm_tsk.h>
  41 #include <linux/ckrm_mem_inline.h>
  42
  43 #include <asm/pgtable.h>
  44 #include <asm/pgalloc.h>
  45 #include <asm/uaccess.h>
  46 #include <asm/mmu_context.h>
  47 #include <asm/cacheflush.h>
  48 #include <asm/tlbflush.h>
  49
  50 /* The idle threads do not count..
  51  * Protected by write_lock_irq(&tasklist_lock)
  52  */
  53 int nr_threads;
  54
  55 int max_threads;
  56 unsigned long total_forks;      /* Handle normal Linux uptimes. */
  57
  58 DEFINE_PER_CPU(unsigned long, process_counts) = 0;
  59
  60 rwlock_t tasklist_lock __cacheline_aligned = RW_LOCK_UNLOCKED;  /* outer */
  61
  62 EXPORT_SYMBOL(tasklist_lock);
  63
  64 int nr_processes(void)
  65 {
  66         int cpu;
  67         int total = 0;
  68
  69         for_each_online_cpu(cpu)
  70                 total += per_cpu(process_counts, cpu);
  71
  72         return total;
  73 }
  74
  75 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
  76 # define alloc_task_struct()    kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
  77 # define free_task_struct(tsk)  kmem_cache_free(task_struct_cachep, (tsk))
  78 static kmem_cache_t *task_struct_cachep;
  79 #endif
  80
  81 static void free_task(struct task_struct *tsk)
  82 {
  83         free_thread_info(tsk->thread_info);
  84         free_task_struct(tsk);
  85 }
  86
  87 void __put_task_struct(struct task_struct *tsk)
  88 {
  89         WARN_ON(!(tsk->state & (TASK_DEAD | TASK_ZOMBIE)));
  90         WARN_ON(atomic_read(&tsk->usage));
  91         WARN_ON(tsk == current);
  92
  93         if (unlikely(tsk->audit_context))
  94                 audit_free(tsk);
  95         security_task_free(tsk);
  96         free_uid(tsk->user);
  97         put_group_info(tsk->group_info);
  98         free_task(tsk);
  99 }
 100
 101 void fastcall add_wait_queue(wait_queue_head_t *q, wait_queue_t * wait)
 102 {
 103         unsigned long flags;
 104
 105         wait->flags &= ~WQ_FLAG_EXCLUSIVE;
 106         spin_lock_irqsave(&q->lock, flags);
 107         __add_wait_queue(q, wait);
 108         spin_unlock_irqrestore(&q->lock, flags);
 109 }
 110
 111 EXPORT_SYMBOL(add_wait_queue);
 112
 113 void fastcall add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t * wait)
 114 {
 115         unsigned long flags;
 116
 117         wait->flags |= WQ_FLAG_EXCLUSIVE;
 118         spin_lock_irqsave(&q->lock, flags);
 119         __add_wait_queue_tail(q, wait);
 120         spin_unlock_irqrestore(&q->lock, flags);
 121 }
 122
 123 EXPORT_SYMBOL(add_wait_queue_exclusive);
 124
 125 void fastcall remove_wait_queue(wait_queue_head_t *q, wait_queue_t * wait)
 126 {
 127         unsigned long flags;
 128
 129         spin_lock_irqsave(&q->lock, flags);
 130         __remove_wait_queue(q, wait);
 131         spin_unlock_irqrestore(&q->lock, flags);
 132 }
 133
 134 EXPORT_SYMBOL(remove_wait_queue);
 135
 136
 137 /*
 138  * Note: we use "set_current_state()" _after_ the wait-queue add,
 139  * because we need a memory barrier there on SMP, so that any
 140  * wake-function that tests for the wait-queue being active
 141  * will be guaranteed to see waitqueue addition _or_ subsequent
 142  * tests in this thread will see the wakeup having taken place.
 143  *
 144  * The spin_unlock() itself is semi-permeable and only protects
 145  * one way (it only protects stuff inside the critical region and
 146  * stops them from bleeding out - it would still allow subsequent
 147  * loads to move into the the critical region).
 148  */
 149 void fastcall prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state)
 150 {
 151         unsigned long flags;
 152
 153         wait->flags &= ~WQ_FLAG_EXCLUSIVE;
 154         spin_lock_irqsave(&q->lock, flags);
 155         if (list_empty(&wait->task_list))
 156                 __add_wait_queue(q, wait);
 157         set_current_state(state);
 158         spin_unlock_irqrestore(&q->lock, flags);
 159 }
 160
 161 EXPORT_SYMBOL(prepare_to_wait);
 162
 163 void fastcall
 164 prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state)
 165 {
 166         unsigned long flags;
 167
 168         wait->flags |= WQ_FLAG_EXCLUSIVE;
 169         spin_lock_irqsave(&q->lock, flags);
 170         if (list_empty(&wait->task_list))
 171                 __add_wait_queue_tail(q, wait);
 172         set_current_state(state);
 173         spin_unlock_irqrestore(&q->lock, flags);
 174 }
 175
 176 EXPORT_SYMBOL(prepare_to_wait_exclusive);
 177
 178 void fastcall finish_wait(wait_queue_head_t *q, wait_queue_t *wait)
 179 {
 180         unsigned long flags;
 181
 182         __set_current_state(TASK_RUNNING);
 183         /*
 184          * We can check for list emptiness outside the lock
 185          * IFF:
 186          *  - we use the "careful" check that verifies both
 187          *    the next and prev pointers, so that there cannot
 188          *    be any half-pending updates in progress on other
 189          *    CPU's that we haven't seen yet (and that might
 190          *    still change the stack area.
 191          * and
 192          *  - all other users take the lock (ie we can only
 193          *    have _one_ other CPU that looks at or modifies
 194          *    the list).
 195          */
 196         if (!list_empty_careful(&wait->task_list)) {
 197                 spin_lock_irqsave(&q->lock, flags);
 198                 list_del_init(&wait->task_list);
 199                 spin_unlock_irqrestore(&q->lock, flags);
 200         }
 201 }
 202
 203 EXPORT_SYMBOL(finish_wait);
 204
 205 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key)
 206 {
 207         int ret = default_wake_function(wait, mode, sync, key);
 208
 209         if (ret)
 210                 list_del_init(&wait->task_list);
 211         return ret;
 212 }
 213
 214 EXPORT_SYMBOL(autoremove_wake_function);
 215
 216 void __init fork_init(unsigned long mempages)
 217 {
 218 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
 219 #ifndef ARCH_MIN_TASKALIGN
 220 #define ARCH_MIN_TASKALIGN      L1_CACHE_BYTES
 221 #endif
 222         /* create a slab on which task_structs can be allocated */
 223         task_struct_cachep =
 224                 kmem_cache_create("task_struct", sizeof(struct task_struct),
 225                         ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL, NULL);
 226 #endif
 227
 228         /*
 229          * The default maximum number of threads is set to a safe
 230          * value: the thread structures can take up at most half
 231          * of memory.
 232          */
 233         max_threads = mempages / (THREAD_SIZE/PAGE_SIZE) / 8;
 234         /*
 235          * we need to allow at least 20 threads to boot a system
 236          */
 237         if(max_threads < 20)
 238                 max_threads = 20;
 239
 240         init_task.rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
 241         init_task.rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
 242 }
 243
 244 static struct task_struct *dup_task_struct(struct task_struct *orig)
 245 {
 246         struct task_struct *tsk;
 247         struct thread_info *ti;
 248
 249         prepare_to_copy(orig);
 250
 251         tsk = alloc_task_struct();
 252         if (!tsk)
 253                 return NULL;
 254
 255         ti = alloc_thread_info(tsk);
 256         if (!ti) {
 257                 free_task_struct(tsk);
 258                 return NULL;
 259         }
 260
 261         *ti = *orig->thread_info;
 262         *tsk = *orig;
 263         tsk->thread_info = ti;
 264         ti->task = tsk;
 265
 266         ckrm_cb_newtask(tsk);
 267         /* One for us, one for whoever does the "release_task()" (usually parent) */
 268         atomic_set(&tsk->usage,2);
 269 #ifdef CONFIG_CKRM_RES_MEM
 270         INIT_LIST_HEAD(&tsk->mm_peers);
 271 #endif
 272         return tsk;
 273 }
 274
 275 #ifdef CONFIG_MMU
 276 static inline int dup_mmap(struct mm_struct * mm, struct mm_struct * oldmm)
 277 {
 278         struct vm_area_struct * mpnt, *tmp, **pprev;
 279         struct rb_node **rb_link, *rb_parent;
 280         int retval;
 281         unsigned long charge;
 282         struct mempolicy *pol;
 283
 284         down_write(&oldmm->mmap_sem);
 285         flush_cache_mm(current->mm);
 286         mm->locked_vm = 0;
 287         mm->mmap = NULL;
 288         mm->mmap_cache = NULL;
 289         mm->free_area_cache = TASK_UNMAPPED_BASE;
 290         mm->map_count = 0;
 291         mm->rss = 0;
 292         cpus_clear(mm->cpu_vm_mask);
 293         mm->mm_rb = RB_ROOT;
 294         rb_link = &mm->mm_rb.rb_node;
 295         rb_parent = NULL;
 296         pprev = &mm->mmap;
 297
 298         /*
 299          * Add it to the mmlist after the parent.
 300          * Doing it this way means that we can order the list,
 301          * and fork() won't mess up the ordering significantly.
 302          * Add it first so that swapoff can see any swap entries.
 303          */
 304         spin_lock(&mmlist_lock);
 305         list_add(&mm->mmlist, &current->mm->mmlist);
 306         mmlist_nr++;
 307         spin_unlock(&mmlist_lock);
 308
 309         for (mpnt = current->mm->mmap ; mpnt ; mpnt = mpnt->vm_next) {
 310                 struct file *file;
 311
 312                 if(mpnt->vm_flags & VM_DONTCOPY)
 313                         continue;
 314                 charge = 0;
 315                 if (mpnt->vm_flags & VM_ACCOUNT) {
 316                         unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
 317                         if (security_vm_enough_memory(len))
 318                                 goto fail_nomem;
 319                         charge = len;
 320                 }
 321                 tmp = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
 322                 if (!tmp)
 323                         goto fail_nomem;
 324                 *tmp = *mpnt;
 325                 pol = mpol_copy(vma_policy(mpnt));
 326                 retval = PTR_ERR(pol);
 327                 if (IS_ERR(pol))
 328                         goto fail_nomem_policy;
 329                 vma_set_policy(tmp, pol);
 330                 tmp->vm_flags &= ~VM_LOCKED;
 331                 tmp->vm_mm = mm;
 332                 tmp->vm_next = NULL;
 333                 anon_vma_link(tmp);
 334                 vma_prio_tree_init(tmp);
 335                 file = tmp->vm_file;
 336                 if (file) {
 337                         struct inode *inode = file->f_dentry->d_inode;
 338                         get_file(file);
 339                         if (tmp->vm_flags & VM_DENYWRITE)
 340                                 atomic_dec(&inode->i_writecount);
 341
 342                         /* insert tmp into the share list, just after mpnt */
 343                         spin_lock(&file->f_mapping->i_mmap_lock);
 344                         flush_dcache_mmap_lock(file->f_mapping);
 345                         vma_prio_tree_add(tmp, mpnt);
 346                         flush_dcache_mmap_unlock(file->f_mapping);
 347                         spin_unlock(&file->f_mapping->i_mmap_lock);
 348                 }
 349
 350                 /*
 351                  * Link in the new vma and copy the page table entries:
 352                  * link in first so that swapoff can see swap entries,
 353                  * and try_to_unmap_one's find_vma find the new vma.
 354                  */
 355                 spin_lock(&mm->page_table_lock);
 356                 *pprev = tmp;
 357                 pprev = &tmp->vm_next;
 358
 359                 __vma_link_rb(mm, tmp, rb_link, rb_parent);
 360                 rb_link = &tmp->vm_rb.rb_right;
 361                 rb_parent = &tmp->vm_rb;
 362
 363                 mm->map_count++;
 364                 retval = copy_page_range(mm, current->mm, tmp);
 365                 spin_unlock(&mm->page_table_lock);
 366
 367                 if (tmp->vm_ops && tmp->vm_ops->open)
 368                         tmp->vm_ops->open(tmp);
 369
 370                 if (retval)
 371                         goto out;
 372         }
 373         retval = 0;
 374
 375 out:
 376         flush_tlb_mm(current->mm);
 377         up_write(&oldmm->mmap_sem);
 378         return retval;
 379 fail_nomem_policy:
 380         kmem_cache_free(vm_area_cachep, tmp);
 381 fail_nomem:
 382         retval = -ENOMEM;
 383         vm_unacct_memory(charge);
 384         goto out;
 385 }
 386
 387 static inline int mm_alloc_pgd(struct mm_struct * mm)
 388 {
 389         mm->pgd = pgd_alloc(mm);
 390         if (unlikely(!mm->pgd))
 391                 return -ENOMEM;
 392         return 0;
 393 }
 394
 395 static inline void mm_free_pgd(struct mm_struct * mm)
 396 {
 397         pgd_free(mm->pgd);
 398 }
 399 #else
 400 #define dup_mmap(mm, oldmm)     (0)
 401 #define mm_alloc_pgd(mm)        (0)
 402 #define mm_free_pgd(mm)
 403 #endif /* CONFIG_MMU */
 404
 405 spinlock_t mmlist_lock __cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED;
 406 int mmlist_nr;
 407
 408 #define allocate_mm()   (kmem_cache_alloc(mm_cachep, SLAB_KERNEL))
 409 #define free_mm(mm)     (kmem_cache_free(mm_cachep, (mm)))
 410
 411 #include <linux/init_task.h>
 412
 413 static struct mm_struct * mm_init(struct mm_struct * mm)
 414 {
 415         atomic_set(&mm->mm_users, 1);
 416         atomic_set(&mm->mm_count, 1);
 417         init_rwsem(&mm->mmap_sem);
 418         mm->core_waiters = 0;
 419         mm->page_table_lock = SPIN_LOCK_UNLOCKED;
 420         mm->ioctx_list_lock = RW_LOCK_UNLOCKED;
 421         mm->ioctx_list = NULL;
 422         mm->default_kioctx = (struct kioctx)INIT_KIOCTX(mm->default_kioctx, *mm);
 423         mm->free_area_cache = TASK_UNMAPPED_BASE;
 424 #ifdef CONFIG_CKRM_RES_MEM
 425         INIT_LIST_HEAD(&mm->tasklist);
 426         mm->peertask_lock = SPIN_LOCK_UNLOCKED;
 427 #endif
 428
 429         if (likely(!mm_alloc_pgd(mm))) {
 430                 mm->def_flags = 0;
 431                 return mm;
 432         }
 433         free_mm(mm);
 434         return NULL;
 435 }
 436
 437 /*
 438  * Allocate and initialize an mm_struct.
 439  */
 440 struct mm_struct * mm_alloc(void)
 441 {
 442         struct mm_struct * mm;
 443
 444         mm = allocate_mm();
 445         if (mm) {
 446                 memset(mm, 0, sizeof(*mm));
 447                 mm = mm_init(mm);
 448 #ifdef CONFIG_CKRM_RES_MEM
 449                 mm->memclass = GET_MEM_CLASS(current);
 450                 mem_class_get(mm->memclass);
 451 #endif
 452         }
 453         return mm;
 454 }
 455
 456 /*
 457  * Called when the last reference to the mm
 458  * is dropped: either by a lazy thread or by
 459  * mmput. Free the page directory and the mm.
 460  */
 461 void fastcall __mmdrop(struct mm_struct *mm)
 462 {
 463         BUG_ON(mm == &init_mm);
 464         mm_free_pgd(mm);
 465         destroy_context(mm);
 466 #ifdef CONFIG_CKRM_RES_MEM
 467         /* class can be null and mm's tasklist can be empty here */
 468         if (mm->memclass) {
 469                 mem_class_put(mm->memclass);
 470                 mm->memclass = NULL;
 471         }
 472 #endif
 473         free_mm(mm);
 474 }
 475
 476 /*
 477  * Decrement the use count and release all resources for an mm.
 478  */
 479 void mmput(struct mm_struct *mm)
 480 {
 481         if (atomic_dec_and_lock(&mm->mm_users, &mmlist_lock)) {
 482                 list_del(&mm->mmlist);
 483                 mmlist_nr--;
 484                 spin_unlock(&mmlist_lock);
 485                 exit_aio(mm);
 486                 exit_mmap(mm);
 487                 mmdrop(mm);
 488         }
 489 }
 490
 491 /*
 492  * Checks if the use count of an mm is non-zero and if so
 493  * returns a reference to it after bumping up the use count.
 494  * If the use count is zero, it means this mm is going away,
 495  * so return NULL.
 496  */
 497 struct mm_struct *mmgrab(struct mm_struct *mm)
 498 {
 499         spin_lock(&mmlist_lock);
 500         if (!atomic_read(&mm->mm_users))
 501                 mm = NULL;
 502         else
 503                 atomic_inc(&mm->mm_users);
 504         spin_unlock(&mmlist_lock);
 505         return mm;
 506 }
 507
 508 /* Please note the differences between mmput and mm_release.
 509  * mmput is called whenever we stop holding onto a mm_struct,
 510  * error success whatever.
 511  *
 512  * mm_release is called after a mm_struct has been removed
 513  * from the current process.
 514  *
 515  * This difference is important for error handling, when we
 516  * only half set up a mm_struct for a new process and need to restore
 517  * the old one.  Because we mmput the new mm_struct before
 518  * restoring the old one. . .
 519  * Eric Biederman 10 January 1998
 520  */
 521 void mm_release(struct task_struct *tsk, struct mm_struct *mm)
 522 {
 523         struct completion *vfork_done = tsk->vfork_done;
 524
 525         /* Get rid of any cached register state */
 526         deactivate_mm(tsk, mm);
 527
 528         /* notify parent sleeping on vfork() */
 529         if (vfork_done) {
 530                 tsk->vfork_done = NULL;
 531                 complete(vfork_done);
 532         }
 533         if (tsk->clear_child_tid && atomic_read(&mm->mm_users) > 1) {
 534                 u32 __user * tidptr = tsk->clear_child_tid;
 535                 tsk->clear_child_tid = NULL;
 536
 537                 /*
 538                  * We don't check the error code - if userspace has
 539                  * not set up a proper pointer then tough luck.
 540                  */
 541                 put_user(0, tidptr);
 542                 sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0);
 543         }
 544 }
 545
 546 static int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
 547 {
 548         struct mm_struct * mm, *oldmm;
 549         int retval;
 550
 551         tsk->min_flt = tsk->maj_flt = 0;
 552         tsk->cmin_flt = tsk->cmaj_flt = 0;
 553         tsk->nvcsw = tsk->nivcsw = tsk->cnvcsw = tsk->cnivcsw = 0;
 554
 555         tsk->mm = NULL;
 556         tsk->active_mm = NULL;
 557
 558         /*
 559          * Are we cloning a kernel thread?
 560          *
 561          * We need to steal a active VM for that..
 562          */
 563         oldmm = current->mm;
 564         if (!oldmm)
 565                 return 0;
 566
 567         if (clone_flags & CLONE_VM) {
 568                 atomic_inc(&oldmm->mm_users);
 569                 mm = oldmm;
 570                 /*
 571                  * There are cases where the PTL is held to ensure no
 572                  * new threads start up in user mode using an mm, which
 573                  * allows optimizing out ipis; the tlb_gather_mmu code
 574                  * is an example.
 575                  */
 576                 spin_unlock_wait(&oldmm->page_table_lock);
 577                 goto good_mm;
 578         }
 579
 580         retval = -ENOMEM;
 581         mm = allocate_mm();
 582         if (!mm)
 583                 goto fail_nomem;
 584
 585         /* Copy the current MM stuff.. */
 586         memcpy(mm, oldmm, sizeof(*mm));
 587         if (!mm_init(mm))
 588                 goto fail_nomem;
 589
 590         if (init_new_context(tsk,mm))
 591                 goto fail_nocontext;
 592
 593         retval = dup_mmap(mm, oldmm);
 594         if (retval)
 595                 goto free_pt;
 596
 597 good_mm:
 598         tsk->mm = mm;
 599         tsk->active_mm = mm;
 600         ckrm_init_mm_to_task(mm, tsk);
 601         return 0;
 602
 603 free_pt:
 604         mmput(mm);
 605 fail_nomem:
 606         return retval;
 607
 608 fail_nocontext:
 609         /*
 610          * If init_new_context() failed, we cannot use mmput() to free the mm
 611          * because it calls destroy_context()
 612          */
 613         mm_free_pgd(mm);
 614         free_mm(mm);
 615         return retval;
 616 }
 617
 618 static inline struct fs_struct *__copy_fs_struct(struct fs_struct *old)
 619 {
 620         struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
 621         /* We don't need to lock fs - think why ;-) */
 622         if (fs) {
 623                 atomic_set(&fs->count, 1);
 624                 fs->lock = RW_LOCK_UNLOCKED;
 625                 fs->umask = old->umask;
 626                 read_lock(&old->lock);
 627                 fs->rootmnt = mntget(old->rootmnt);
 628                 fs->root = dget(old->root);
 629                 fs->pwdmnt = mntget(old->pwdmnt);
 630                 fs->pwd = dget(old->pwd);
 631                 if (old->altroot) {
 632                         fs->altrootmnt = mntget(old->altrootmnt);
 633                         fs->altroot = dget(old->altroot);
 634                 } else {
 635                         fs->altrootmnt = NULL;
 636                         fs->altroot = NULL;
 637                 }
 638                 read_unlock(&old->lock);
 639         }
 640         return fs;
 641 }
 642
 643 struct fs_struct *copy_fs_struct(struct fs_struct *old)
 644 {
 645         return __copy_fs_struct(old);
 646 }
 647
 648 EXPORT_SYMBOL_GPL(copy_fs_struct);
 649
 650 static inline int copy_fs(unsigned long clone_flags, struct task_struct * tsk)
 651 {
 652         if (clone_flags & CLONE_FS) {
 653                 atomic_inc(&current->fs->count);
 654                 return 0;
 655         }
 656         tsk->fs = __copy_fs_struct(current->fs);
 657         if (!tsk->fs)
 658                 return -ENOMEM;
 659         return 0;
 660 }
 661
 662 static int count_open_files(struct files_struct *files, int size)
 663 {
 664         int i;
 665
 666         /* Find the last open fd */
 667         for (i = size/(8*sizeof(long)); i > 0; ) {
 668                 if (files->open_fds->fds_bits[--i])
 669                         break;
 670         }
 671         i = (i+1) * 8 * sizeof(long);
 672         return i;
 673 }
 674
 675 static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
 676 {
 677         struct files_struct *oldf, *newf;
 678         struct file **old_fds, **new_fds;
 679         int open_files, nfds, size, i, error = 0;
 680
 681         /*
 682          * A background process may not have any files ...
 683          */
 684         oldf = current->files;
 685         if (!oldf)
 686                 goto out;
 687
 688         if (clone_flags & CLONE_FILES) {
 689                 atomic_inc(&oldf->count);
 690                 goto out;
 691         }
 692
 693         /*
 694          * Note: we may be using current for both targets (See exec.c)
 695          * This works because we cache current->files (old) as oldf. Don't
 696          * break this.
 697          */
 698         tsk->files = NULL;
 699         error = -ENOMEM;
 700         newf = kmem_cache_alloc(files_cachep, SLAB_KERNEL);
 701         if (!newf)
 702                 goto out;
 703
 704         atomic_set(&newf->count, 1);
 705
 706         newf->file_lock     = SPIN_LOCK_UNLOCKED;
 707         newf->next_fd       = 0;
 708         newf->max_fds       = NR_OPEN_DEFAULT;
 709         newf->max_fdset     = __FD_SETSIZE;
 710         newf->close_on_exec = &newf->close_on_exec_init;
 711         newf->open_fds      = &newf->open_fds_init;
 712         newf->fd            = &newf->fd_array[0];
 713
 714         /* We don't yet have the oldf readlock, but even if the old
 715            fdset gets grown now, we'll only copy up to "size" fds */
 716         size = oldf->max_fdset;
 717         if (size > __FD_SETSIZE) {
 718                 newf->max_fdset = 0;
 719                 spin_lock(&newf->file_lock);
 720                 error = expand_fdset(newf, size-1);
 721                 spin_unlock(&newf->file_lock);
 722                 if (error)
 723                         goto out_release;
 724         }
 725         spin_lock(&oldf->file_lock);
 726
 727         open_files = count_open_files(oldf, size);
 728
 729         /*
 730          * Check whether we need to allocate a larger fd array.
 731          * Note: we're not a clone task, so the open count won't
 732          * change.
 733          */
 734         nfds = NR_OPEN_DEFAULT;
 735         if (open_files > nfds) {
 736                 spin_unlock(&oldf->file_lock);
 737                 newf->max_fds = 0;
 738                 spin_lock(&newf->file_lock);
 739                 error = expand_fd_array(newf, open_files-1);
 740                 spin_unlock(&newf->file_lock);
 741                 if (error)
 742                         goto out_release;
 743                 nfds = newf->max_fds;
 744                 spin_lock(&oldf->file_lock);
 745         }
 746
 747         old_fds = oldf->fd;
 748         new_fds = newf->fd;
 749
 750         memcpy(newf->open_fds->fds_bits, oldf->open_fds->fds_bits, open_files/8);
 751         memcpy(newf->close_on_exec->fds_bits, oldf->close_on_exec->fds_bits, open_files/8);
 752
 753         for (i = open_files; i != 0; i--) {
 754                 struct file *f = *old_fds++;
 755                 if (f)
 756                         get_file(f);
 757                 *new_fds++ = f;
 758         }
 759         spin_unlock(&oldf->file_lock);
 760
 761         /* compute the remainder to be cleared */
 762         size = (newf->max_fds - open_files) * sizeof(struct file *);
 763
 764         /* This is long word aligned thus could use a optimized version */
 765         memset(new_fds, 0, size);
 766
 767         if (newf->max_fdset > open_files) {
 768                 int left = (newf->max_fdset-open_files)/8;
 769                 int start = open_files / (8 * sizeof(unsigned long));
 770
 771                 memset(&newf->open_fds->fds_bits[start], 0, left);
 772                 memset(&newf->close_on_exec->fds_bits[start], 0, left);
 773         }
 774
 775         tsk->files = newf;
 776         error = 0;
 777 out:
 778         return error;
 779
 780 out_release:
 781         free_fdset (newf->close_on_exec, newf->max_fdset);
 782         free_fdset (newf->open_fds, newf->max_fdset);
 783         kmem_cache_free(files_cachep, newf);
 784         goto out;
 785 }
 786
 787 /*
 788  *      Helper to unshare the files of the current task.
 789  *      We don't want to expose copy_files internals to
 790  *      the exec layer of the kernel.
 791  */
 792
 793 int unshare_files(void)
 794 {
 795         struct files_struct *files  = current->files;
 796         int rc;
 797
 798         if(!files)
 799                 BUG();
 800
 801         /* This can race but the race causes us to copy when we don't
 802            need to and drop the copy */
 803         if(atomic_read(&files->count) == 1)
 804         {
 805                 atomic_inc(&files->count);
 806                 return 0;
 807         }
 808         rc = copy_files(0, current);
 809         if(rc)
 810                 current->files = files;
 811         return rc;
 812 }
 813
 814 EXPORT_SYMBOL(unshare_files);
 815
 816 static inline int copy_sighand(unsigned long clone_flags, struct task_struct * tsk)
 817 {
 818         struct sighand_struct *sig;
 819
 820         if (clone_flags & (CLONE_SIGHAND | CLONE_THREAD)) {
 821                 atomic_inc(&current->sighand->count);
 822                 return 0;
 823         }
 824         sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
 825         tsk->sighand = sig;
 826         if (!sig)
 827                 return -ENOMEM;
 828         spin_lock_init(&sig->siglock);
 829         atomic_set(&sig->count, 1);
 830         memcpy(sig->action, current->sighand->action, sizeof(sig->action));
 831         return 0;
 832 }
 833
 834 static inline int copy_signal(unsigned long clone_flags, struct task_struct * tsk)
 835 {
 836         struct signal_struct *sig;
 837
 838         if (clone_flags & CLONE_THREAD) {
 839                 atomic_inc(&current->signal->count);
 840                 return 0;
 841         }
 842         sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
 843         tsk->signal = sig;
 844         if (!sig)
 845                 return -ENOMEM;
 846         atomic_set(&sig->count, 1);
 847         sig->group_exit = 0;
 848         sig->group_exit_code = 0;
 849         sig->group_exit_task = NULL;
 850         sig->group_stop_count = 0;
 851         sig->curr_target = NULL;
 852         init_sigpending(&sig->shared_pending);
 853         INIT_LIST_HEAD(&sig->posix_timers);
 854
 855         sig->tty = current->signal->tty;
 856         sig->pgrp = process_group(current);
 857         sig->session = current->signal->session;
 858         sig->leader = 0;        /* session leadership doesn't inherit */
 859         sig->tty_old_pgrp = 0;
 860
 861         return 0;
 862 }
 863
 864 static inline void copy_flags(unsigned long clone_flags, struct task_struct *p)
 865 {
 866         unsigned long new_flags = p->flags;
 867
 868         new_flags &= ~PF_SUPERPRIV;
 869         new_flags |= PF_FORKNOEXEC;
 870         if (!(clone_flags & CLONE_PTRACE))
 871                 p->ptrace = 0;
 872         p->flags = new_flags;
 873 }
 874
 875 asmlinkage long sys_set_tid_address(int __user *tidptr)
 876 {
 877         current->clear_child_tid = tidptr;
 878
 879         return current->pid;
 880 }
 881
 882 /*
 883  * This creates a new process as a copy of the old one,
 884  * but does not actually start it yet.
 885  *
 886  * It copies the registers, and all the appropriate
 887  * parts of the process environment (as per the clone
 888  * flags). The actual kick-off is left to the caller.
 889  */
 890 struct task_struct *copy_process(unsigned long clone_flags,
 891                                  unsigned long stack_start,
 892                                  struct pt_regs *regs,
 893                                  unsigned long stack_size,
 894                                  int __user *parent_tidptr,
 895                                  int __user *child_tidptr)
 896 {
 897         int retval;
 898         struct task_struct *p = NULL;
 899
 900         if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
 901                 return ERR_PTR(-EINVAL);
 902
 903         /*
 904          * Thread groups must share signals as well, and detached threads
 905          * can only be started up within the thread group.
 906          */
 907         if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
 908                 return ERR_PTR(-EINVAL);
 909
 910         /*
 911          * Shared signal handlers imply shared VM. By way of the above,
 912          * thread groups also imply shared VM. Blocking this case allows
 913          * for various simplifications in other code.
 914          */
 915         if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
 916                 return ERR_PTR(-EINVAL);
 917
 918         retval = security_task_create(clone_flags);
 919         if (retval)
 920                 goto fork_out;
 921
 922         retval = -ENOMEM;
 923         p = dup_task_struct(current);
 924         if (!p)
 925                 goto fork_out;
 926
 927         retval = -EAGAIN;
 928         if (atomic_read(&p->user->processes) >=
 929                         p->rlim[RLIMIT_NPROC].rlim_cur) {
 930                 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
 931                                 p->user != &root_user)
 932                         goto bad_fork_free;
 933         }
 934
 935         atomic_inc(&p->user->__count);
 936         atomic_inc(&p->user->processes);
 937         get_group_info(p->group_info);
 938
 939         /*
 940          * If multiple threads are within copy_process(), then this check
 941          * triggers too late. This doesn't hurt, the check is only there
 942          * to stop root fork bombs.
 943          */
 944         if (nr_threads >= max_threads)
 945                 goto bad_fork_cleanup_count;
 946
 947         if (!try_module_get(p->thread_info->exec_domain->module))
 948                 goto bad_fork_cleanup_count;
 949
 950         if (p->binfmt && !try_module_get(p->binfmt->module))
 951                 goto bad_fork_cleanup_put_domain;
 952
 953         init_delays(p);
 954         p->did_exec = 0;
 955         copy_flags(clone_flags, p);
 956         if (clone_flags & CLONE_IDLETASK)
 957                 p->pid = 0;
 958         else {
 959                 p->pid = alloc_pidmap();
 960                 if (p->pid == -1)
 961                         goto bad_fork_cleanup;
 962         }
 963         retval = -EFAULT;
 964         if (clone_flags & CLONE_PARENT_SETTID)
 965                 if (put_user(p->pid, parent_tidptr))
 966                         goto bad_fork_cleanup;
 967
 968         p->proc_dentry = NULL;
 969
 970         INIT_LIST_HEAD(&p->children);
 971         INIT_LIST_HEAD(&p->sibling);
 972         init_waitqueue_head(&p->wait_chldexit);
 973         p->vfork_done = NULL;
 974         spin_lock_init(&p->alloc_lock);
 975         spin_lock_init(&p->proc_lock);
 976
 977         clear_tsk_thread_flag(p, TIF_SIGPENDING);
 978         init_sigpending(&p->pending);
 979
 980         p->it_real_value = p->it_virt_value = p->it_prof_value = 0;
 981         p->it_real_incr = p->it_virt_incr = p->it_prof_incr = 0;
 982         init_timer(&p->real_timer);
 983         p->real_timer.data = (unsigned long) p;
 984
 985         p->utime = p->stime = 0;
 986         p->cutime = p->cstime = 0;
 987         p->lock_depth = -1;             /* -1 = no lock */
 988         p->start_time = get_jiffies_64();
 989         p->security = NULL;
 990         p->io_context = NULL;
 991         p->audit_context = NULL;
 992 #ifdef CONFIG_NUMA
 993         p->mempolicy = mpol_copy(p->mempolicy);
 994         if (IS_ERR(p->mempolicy)) {
 995                 retval = PTR_ERR(p->mempolicy);
 996                 p->mempolicy = NULL;
 997                 goto bad_fork_cleanup;
 998         }
 999 #endif
1000
1001         if ((retval = security_task_alloc(p)))
1002                 goto bad_fork_cleanup_policy;
1003         if ((retval = audit_alloc(p)))
1004                 goto bad_fork_cleanup_security;
1005         /* copy all the process information */
1006         if ((retval = copy_semundo(clone_flags, p)))
1007                 goto bad_fork_cleanup_audit;
1008         if ((retval = copy_files(clone_flags, p)))
1009                 goto bad_fork_cleanup_semundo;
1010         if ((retval = copy_fs(clone_flags, p)))
1011                 goto bad_fork_cleanup_files;
1012         if ((retval = copy_sighand(clone_flags, p)))
1013                 goto bad_fork_cleanup_fs;
1014         if ((retval = copy_signal(clone_flags, p)))
1015                 goto bad_fork_cleanup_sighand;
1016         if ((retval = copy_mm(clone_flags, p)))
1017                 goto bad_fork_cleanup_signal;
1018         if ((retval = copy_namespace(clone_flags, p)))
1019                 goto bad_fork_cleanup_mm;
1020         retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
1021         if (retval)
1022                 goto bad_fork_cleanup_namespace;
1023
1024         p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
1025         /*
1026          * Clear TID on mm_release()?
1027          */
1028         p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL;
1029
1030         /*
1031          * Syscall tracing should be turned off in the child regardless
1032          * of CLONE_PTRACE.
1033          */
1034         clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
1035
1036         /* Our parent execution domain becomes current domain
1037            These must match for thread signalling to apply */
1038
1039         p->parent_exec_id = p->self_exec_id;
1040
1041         /* ok, now we should be set up.. */
1042         p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
1043         p->pdeath_signal = 0;
1044
1045         /* Perform scheduler related setup */
1046         sched_fork(p);
1047
1048         /*
1049          * Ok, make it visible to the rest of the system.
1050          * We dont wake it up yet.
1051          */
1052         p->tgid = p->pid;
1053         p->group_leader = p;
1054         INIT_LIST_HEAD(&p->ptrace_children);
1055         INIT_LIST_HEAD(&p->ptrace_list);
1056
1057         /* Need tasklist lock for parent etc handling! */
1058         write_lock_irq(&tasklist_lock);
1059         /*
1060          * Check for pending SIGKILL! The new thread should not be allowed
1061          * to slip out of an OOM kill. (or normal SIGKILL.)
1062          */
1063         if (sigismember(&current->pending.signal, SIGKILL)) {
1064                 write_unlock_irq(&tasklist_lock);
1065                 retval = -EINTR;
1066                 goto bad_fork_cleanup_namespace;
1067         }
1068
1069         /* CLONE_PARENT re-uses the old parent */
1070         if (clone_flags & CLONE_PARENT)
1071                 p->real_parent = current->real_parent;
1072         else
1073                 p->real_parent = current;
1074         p->parent = p->real_parent;
1075
1076         if (clone_flags & CLONE_THREAD) {
1077                 spin_lock(&current->sighand->siglock);
1078                 /*
1079                  * Important: if an exit-all has been started then
1080                  * do not create this new thread - the whole thread
1081                  * group is supposed to exit anyway.
1082                  */
1083                 if (current->signal->group_exit) {
1084                         spin_unlock(&current->sighand->siglock);
1085                         write_unlock_irq(&tasklist_lock);
1086                         retval = -EAGAIN;
1087                         goto bad_fork_cleanup_namespace;
1088                 }
1089                 p->tgid = current->tgid;
1090                 p->group_leader = current->group_leader;
1091
1092                 if (current->signal->group_stop_count > 0) {
1093                         /*
1094                          * There is an all-stop in progress for the group.
1095                          * We ourselves will stop as soon as we check signals.
1096                          * Make the new thread part of that group stop too.
1097                          */
1098                         current->signal->group_stop_count++;
1099                         set_tsk_thread_flag(p, TIF_SIGPENDING);
1100                 }
1101
1102                 spin_unlock(&current->sighand->siglock);
1103         }
1104
1105         SET_LINKS(p);
1106         if (p->ptrace & PT_PTRACED)
1107                 __ptrace_link(p, current->parent);
1108
1109         attach_pid(p, PIDTYPE_PID, p->pid);
1110         if (thread_group_leader(p)) {
1111                 attach_pid(p, PIDTYPE_TGID, p->tgid);
1112                 attach_pid(p, PIDTYPE_PGID, process_group(p));
1113                 attach_pid(p, PIDTYPE_SID, p->signal->session);
1114                 if (p->pid)
1115                         __get_cpu_var(process_counts)++;
1116         } else
1117                 link_pid(p, p->pids + PIDTYPE_TGID, &p->group_leader->pids[PIDTYPE_TGID].pid);
1118
1119         nr_threads++;
1120         write_unlock_irq(&tasklist_lock);
1121         retval = 0;
1122
1123 fork_out:
1124         if (retval)
1125                 return ERR_PTR(retval);
1126         return p;
1127
1128 bad_fork_cleanup_namespace:
1129         exit_namespace(p);
1130 bad_fork_cleanup_mm:
1131         exit_mm(p);
1132         if (p->active_mm)
1133                 mmdrop(p->active_mm);
1134 bad_fork_cleanup_signal:
1135         exit_signal(p);
1136 bad_fork_cleanup_sighand:
1137         exit_sighand(p);
1138 bad_fork_cleanup_fs:
1139         exit_fs(p); /* blocking */
1140 bad_fork_cleanup_files:
1141         exit_files(p); /* blocking */
1142 bad_fork_cleanup_semundo:
1143         exit_sem(p);
1144 bad_fork_cleanup_audit:
1145         audit_free(p);
1146 bad_fork_cleanup_security:
1147         security_task_free(p);
1148 bad_fork_cleanup_policy:
1149 #ifdef CONFIG_NUMA
1150         mpol_free(p->mempolicy);
1151 #endif
1152 bad_fork_cleanup:
1153         if (p->pid > 0)
1154                 free_pidmap(p->pid);
1155         if (p->binfmt)
1156                 module_put(p->binfmt->module);
1157 bad_fork_cleanup_put_domain:
1158         module_put(p->thread_info->exec_domain->module);
1159 bad_fork_cleanup_count:
1160         put_group_info(p->group_info);
1161         atomic_dec(&p->user->processes);
1162         free_uid(p->user);
1163 bad_fork_free:
1164         free_task(p);
1165         goto fork_out;
1166 }
1167
1168 static inline int fork_traceflag (unsigned clone_flags)
1169 {
1170         if (clone_flags & (CLONE_UNTRACED | CLONE_IDLETASK))
1171                 return 0;
1172         else if (clone_flags & CLONE_VFORK) {
1173                 if (current->ptrace & PT_TRACE_VFORK)
1174                         return PTRACE_EVENT_VFORK;
1175         } else if ((clone_flags & CSIGNAL) != SIGCHLD) {
1176                 if (current->ptrace & PT_TRACE_CLONE)
1177                         return PTRACE_EVENT_CLONE;
1178         } else if (current->ptrace & PT_TRACE_FORK)
1179                 return PTRACE_EVENT_FORK;
1180
1181         return 0;
1182 }
1183
1184 /*
1185  *  Ok, this is the main fork-routine.
1186  *
1187  * It copies the process, and if successful kick-starts
1188  * it and waits for it to finish using the VM if required.
1189  */
1190 long do_fork(unsigned long clone_flags,
1191               unsigned long stack_start,
1192               struct pt_regs *regs,
1193               unsigned long stack_size,
1194               int __user *parent_tidptr,
1195               int __user *child_tidptr)
1196 {
1197         struct task_struct *p;
1198         int trace = 0;
1199         long pid;
1200
1201         if (unlikely(current->ptrace)) {
1202                 trace = fork_traceflag (clone_flags);
1203                 if (trace)
1204                         clone_flags |= CLONE_PTRACE;
1205         }
1206
1207 #ifdef CONFIG_CKRM_TYPE_TASKCLASS
1208         if (numtasks_get_ref(current->taskclass, 0) == 0) {
1209                 return -ENOMEM;
1210         }
1211 #endif
1212
1213         p = copy_process(clone_flags, stack_start, regs, stack_size, parent_tidptr, child_tidptr);
1214         /*
1215          * Do this prior waking up the new thread - the thread pointer
1216          * might get invalid after that point, if the thread exits quickly.
1217          */
1218         pid = IS_ERR(p) ? PTR_ERR(p) : p->pid;
1219
1220         if (!IS_ERR(p)) {
1221                 struct completion vfork;
1222
1223                 ckrm_cb_fork(p);
1224
1225                 if (clone_flags & CLONE_VFORK) {
1226                         p->vfork_done = &vfork;
1227                         init_completion(&vfork);
1228                 }
1229
1230                 if ((p->ptrace & PT_PTRACED) || (clone_flags & CLONE_STOPPED)) {
1231                         /*
1232                          * We'll start up with an immediate SIGSTOP.
1233                          */
1234                         sigaddset(&p->pending.signal, SIGSTOP);
1235                         set_tsk_thread_flag(p, TIF_SIGPENDING);
1236                 }
1237
1238                 if (!(clone_flags & CLONE_STOPPED)) {
1239                         /*
1240                          * Do the wakeup last. On SMP we treat fork() and
1241                          * CLONE_VM separately, because fork() has already
1242                          * created cache footprint on this CPU (due to
1243                          * copying the pagetables), hence migration would
1244                          * probably be costy. Threads on the other hand
1245                          * have less traction to the current CPU, and if
1246                          * there's an imbalance then the scheduler can
1247                          * migrate this fresh thread now, before it
1248                          * accumulates a larger cache footprint:
1249                          */
1250                         if (clone_flags & CLONE_VM)
1251                                 wake_up_forked_thread(p);
1252                         else
1253                                 wake_up_forked_process(p);
1254                 } else {
1255                         int cpu = get_cpu();
1256
1257                         p->state = TASK_STOPPED;
1258                         if (cpu_is_offline(task_cpu(p)))
1259                                 set_task_cpu(p, cpu);
1260
1261                         put_cpu();
1262                 }
1263                 ++total_forks;
1264
1265                 if (unlikely (trace)) {
1266                         current->ptrace_message = pid;
1267                         ptrace_notify ((trace << 8) | SIGTRAP);
1268                 }
1269
1270                 if (clone_flags & CLONE_VFORK) {
1271                         wait_for_completion(&vfork);
1272                         if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE))
1273                                 ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP);
1274                 } else
1275                         /*
1276                          * Let the child process run first, to avoid most of the
1277                          * COW overhead when the child exec()s afterwards.
1278                          */
1279                         set_need_resched();
1280         } else {
1281 #ifdef CONFIG_CKRM_TYPE_TASKCLASS
1282                 numtasks_put_ref(current->taskclass);
1283 #endif
1284         }
1285         return pid;
1286 }
1287
1288 /* SLAB cache for signal_struct structures (tsk->signal) */
1289 kmem_cache_t *signal_cachep;
1290
1291 /* SLAB cache for sighand_struct structures (tsk->sighand) */
1292 kmem_cache_t *sighand_cachep;
1293
1294 /* SLAB cache for files_struct structures (tsk->files) */
1295 kmem_cache_t *files_cachep;
1296
1297 /* SLAB cache for fs_struct structures (tsk->fs) */
1298 kmem_cache_t *fs_cachep;
1299
1300 /* SLAB cache for vm_area_struct structures */
1301 kmem_cache_t *vm_area_cachep;
1302
1303 /* SLAB cache for mm_struct structures (tsk->mm) */
1304 kmem_cache_t *mm_cachep;
1305
1306 void __init proc_caches_init(void)
1307 {
1308         sighand_cachep = kmem_cache_create("sighand_cache",
1309                         sizeof(struct sighand_struct), 0,
1310                         SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1311         signal_cachep = kmem_cache_create("signal_cache",
1312                         sizeof(struct signal_struct), 0,
1313                         SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1314         files_cachep = kmem_cache_create("files_cache",
1315                         sizeof(struct files_struct), 0,
1316                         SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1317         fs_cachep = kmem_cache_create("fs_cache",
1318                         sizeof(struct fs_struct), 0,
1319                         SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1320         vm_area_cachep = kmem_cache_create("vm_area_struct",
1321                         sizeof(struct vm_area_struct), 0,
1322                         SLAB_PANIC, NULL, NULL);
1323         mm_cachep = kmem_cache_create("mm_struct",
1324                         sizeof(struct mm_struct), 0,
1325                         SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1326 }