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/compiler.h>
  25
  26 #include <asm/pgtable.h>
  27 #include <asm/pgalloc.h>
  28 #include <asm/uaccess.h>
  29 #include <asm/mmu_context.h>
  30
  31 /* The idle threads do not count.. */
  32 int nr_threads;
  33 int nr_running;
  34
  35 int max_threads;
  36 unsigned long total_forks;      /* Handle normal Linux uptimes. */
  37 int last_pid;
  38
  39 struct task_struct *pidhash[PIDHASH_SZ];
  40
  41 void add_wait_queue(wait_queue_head_t *q, wait_queue_t * wait)
  42 {
  43         unsigned long flags;
  44
  45         wait->flags &= ~WQ_FLAG_EXCLUSIVE;
  46         wq_write_lock_irqsave(&q->lock, flags);
  47         __add_wait_queue(q, wait);
  48         wq_write_unlock_irqrestore(&q->lock, flags);
  49 }
  50
  51 void add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t * wait)
  52 {
  53         unsigned long flags;
  54
  55         wait->flags |= WQ_FLAG_EXCLUSIVE;
  56         wq_write_lock_irqsave(&q->lock, flags);
  57         __add_wait_queue_tail(q, wait);
  58         wq_write_unlock_irqrestore(&q->lock, flags);
  59 }
  60
  61 void remove_wait_queue(wait_queue_head_t *q, wait_queue_t * wait)
  62 {
  63         unsigned long flags;
  64
  65         wq_write_lock_irqsave(&q->lock, flags);
  66         __remove_wait_queue(q, wait);
  67         wq_write_unlock_irqrestore(&q->lock, flags);
  68 }
  69
  70 void __init fork_init(unsigned long mempages)
  71 {
  72         /*
  73          * The default maximum number of threads is set to a safe
  74          * value: the thread structures can take up at most half
  75          * of memory.
  76          */
  77         max_threads = mempages / (THREAD_SIZE/PAGE_SIZE) / 8;
  78
  79         init_task.rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
  80         init_task.rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
  81 }
  82
  83 /* Protects next_safe and last_pid. */
  84 spinlock_t lastpid_lock = SPIN_LOCK_UNLOCKED;
  85
  86 static int get_pid(unsigned long flags)
  87 {
  88         static int next_safe = PID_MAX;
  89         struct task_struct *p;
  90         int pid, beginpid;
  91
  92         if (flags & CLONE_PID)
  93                 return current->pid;
  94
  95         spin_lock(&lastpid_lock);
  96         beginpid = last_pid;
  97         if((++last_pid) & 0xffff8000) {
  98                 last_pid = 300;         /* Skip daemons etc. */
  99                 goto inside;
 100         }
 101         if(last_pid >= next_safe) {
 102 inside:
 103                 next_safe = PID_MAX;
 104                 read_lock(&tasklist_lock);
 105         repeat:
 106                 for_each_task(p) {
 107                         if(p->pid == last_pid   ||
 108                            p->pgrp == last_pid  ||
 109                            p->tgid == last_pid  ||
 110                            p->session == last_pid) {
 111                                 if(++last_pid >= next_safe) {
 112                                         if(last_pid & 0xffff8000)
 113                                                 last_pid = 300;
 114                                         next_safe = PID_MAX;
 115                                 }
 116                                 if(unlikely(last_pid == beginpid))
 117                                         goto nomorepids;
 118                                 goto repeat;
 119                         }
 120                         if(p->pid > last_pid && next_safe > p->pid)
 121                                 next_safe = p->pid;
 122                         if(p->pgrp > last_pid && next_safe > p->pgrp)
 123                                 next_safe = p->pgrp;
 124                         if(p->tgid > last_pid && next_safe > p->tgid)
 125                                 next_safe = p->tgid;
 126                         if(p->session > last_pid && next_safe > p->session)
 127                                 next_safe = p->session;
 128                 }
 129                 read_unlock(&tasklist_lock);
 130         }
 131         pid = last_pid;
 132         spin_unlock(&lastpid_lock);
 133
 134         return pid;
 135
 136 nomorepids:
 137         read_unlock(&tasklist_lock);
 138         spin_unlock(&lastpid_lock);
 139         return 0;
 140 }
 141
 142 static inline int dup_mmap(struct mm_struct * mm)
 143 {
 144         struct vm_area_struct * mpnt, *tmp, **pprev;
 145         int retval;
 146
 147         flush_cache_mm(current->mm);
 148         mm->locked_vm = 0;
 149         mm->mmap = NULL;
 150         mm->mmap_cache = NULL;
 151         mm->map_count = 0;
 152         mm->rss = 0;
 153         mm->cpu_vm_mask = 0;
 154         mm->swap_address = 0;
 155         pprev = &mm->mmap;
 156
 157         /*
 158          * Add it to the mmlist after the parent.
 159          * Doing it this way means that we can order the list,
 160          * and fork() won't mess up the ordering significantly.
 161          * Add it first so that swapoff can see any swap entries.
 162          */
 163         spin_lock(&mmlist_lock);
 164         list_add(&mm->mmlist, &current->mm->mmlist);
 165         mmlist_nr++;
 166         spin_unlock(&mmlist_lock);
 167
 168         for (mpnt = current->mm->mmap ; mpnt ; mpnt = mpnt->vm_next) {
 169                 struct file *file;
 170
 171                 retval = -ENOMEM;
 172                 if(mpnt->vm_flags & VM_DONTCOPY)
 173                         continue;
 174                 tmp = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
 175                 if (!tmp)
 176                         goto fail_nomem;
 177                 *tmp = *mpnt;
 178                 tmp->vm_flags &= ~VM_LOCKED;
 179                 tmp->vm_mm = mm;
 180                 tmp->vm_next = NULL;
 181                 file = tmp->vm_file;
 182                 if (file) {
 183                         struct inode *inode = file->f_dentry->d_inode;
 184                         get_file(file);
 185                         if (tmp->vm_flags & VM_DENYWRITE)
 186                                 atomic_dec(&inode->i_writecount);
 187
 188                         /* insert tmp into the share list, just after mpnt */
 189                         spin_lock(&inode->i_mapping->i_shared_lock);
 190                         if((tmp->vm_next_share = mpnt->vm_next_share) != NULL)
 191                                 mpnt->vm_next_share->vm_pprev_share =
 192                                         &tmp->vm_next_share;
 193                         mpnt->vm_next_share = tmp;
 194                         tmp->vm_pprev_share = &mpnt->vm_next_share;
 195                         spin_unlock(&inode->i_mapping->i_shared_lock);
 196                 }
 197
 198                 /*
 199                  * Link in the new vma and copy the page table entries:
 200                  * link in first so that swapoff can see swap entries.
 201                  */
 202                 spin_lock(&mm->page_table_lock);
 203                 *pprev = tmp;
 204                 pprev = &tmp->vm_next;
 205                 mm->map_count++;
 206                 retval = copy_page_range(mm, current->mm, tmp);
 207                 spin_unlock(&mm->page_table_lock);
 208
 209                 if (tmp->vm_ops && tmp->vm_ops->open)
 210                         tmp->vm_ops->open(tmp);
 211
 212                 if (retval)
 213                         goto fail_nomem;
 214         }
 215         retval = 0;
 216         build_mmap_rb(mm);
 217
 218 fail_nomem:
 219         flush_tlb_mm(current->mm);
 220         return retval;
 221 }
 222
 223 spinlock_t mmlist_lock __cacheline_aligned = SPIN_LOCK_UNLOCKED;
 224 int mmlist_nr;
 225
 226 #define allocate_mm()   (kmem_cache_alloc(mm_cachep, SLAB_KERNEL))
 227 #define free_mm(mm)     (kmem_cache_free(mm_cachep, (mm)))
 228
 229 static struct mm_struct * mm_init(struct mm_struct * mm)
 230 {
 231         atomic_set(&mm->mm_users, 1);
 232         atomic_set(&mm->mm_count, 1);
 233         init_rwsem(&mm->mmap_sem);
 234         mm->page_table_lock = SPIN_LOCK_UNLOCKED;
 235         mm->pgd = pgd_alloc(mm);
 236         mm->def_flags = 0;
 237         if (mm->pgd)
 238                 return mm;
 239         free_mm(mm);
 240         return NULL;
 241 }
 242
 243
 244 /*
 245  * Allocate and initialize an mm_struct.
 246  */
 247 struct mm_struct * mm_alloc(void)
 248 {
 249         struct mm_struct * mm;
 250
 251         mm = allocate_mm();
 252         if (mm) {
 253                 memset(mm, 0, sizeof(*mm));
 254                 return mm_init(mm);
 255         }
 256         return NULL;
 257 }
 258
 259 /*
 260  * Called when the last reference to the mm
 261  * is dropped: either by a lazy thread or by
 262  * mmput. Free the page directory and the mm.
 263  */
 264 inline void __mmdrop(struct mm_struct *mm)
 265 {
 266         BUG_ON(mm == &init_mm);
 267         pgd_free(mm->pgd);
 268         destroy_context(mm);
 269         free_mm(mm);
 270 }
 271
 272 /*
 273  * Decrement the use count and release all resources for an mm.
 274  */
 275 void mmput(struct mm_struct *mm)
 276 {
 277         if (atomic_dec_and_lock(&mm->mm_users, &mmlist_lock)) {
 278                 extern struct mm_struct *swap_mm;
 279                 if (swap_mm == mm)
 280                         swap_mm = list_entry(mm->mmlist.next, struct mm_struct, mmlist);
 281                 list_del(&mm->mmlist);
 282                 mmlist_nr--;
 283                 spin_unlock(&mmlist_lock);
 284                 exit_mmap(mm);
 285                 mmdrop(mm);
 286         }
 287 }
 288
 289 /* Please note the differences between mmput and mm_release.
 290  * mmput is called whenever we stop holding onto a mm_struct,
 291  * error success whatever.
 292  *
 293  * mm_release is called after a mm_struct has been removed
 294  * from the current process.
 295  *
 296  * This difference is important for error handling, when we
 297  * only half set up a mm_struct for a new process and need to restore
 298  * the old one.  Because we mmput the new mm_struct before
 299  * restoring the old one. . .
 300  * Eric Biederman 10 January 1998
 301  */
 302 void mm_release(void)
 303 {
 304         struct task_struct *tsk = current;
 305         struct completion *vfork_done = tsk->vfork_done;
 306
 307         /* notify parent sleeping on vfork() */
 308         if (vfork_done) {
 309                 tsk->vfork_done = NULL;
 310                 complete(vfork_done);
 311         }
 312 }
 313
 314 static int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
 315 {
 316         struct mm_struct * mm, *oldmm;
 317         int retval;
 318
 319         tsk->min_flt = tsk->maj_flt = 0;
 320         tsk->cmin_flt = tsk->cmaj_flt = 0;
 321         tsk->nswap = tsk->cnswap = 0;
 322
 323         tsk->mm = NULL;
 324         tsk->active_mm = NULL;
 325
 326         /*
 327          * Are we cloning a kernel thread?
 328          *
 329          * We need to steal a active VM for that..
 330          */
 331         oldmm = current->mm;
 332         if (!oldmm)
 333                 return 0;
 334
 335         if (clone_flags & CLONE_VM) {
 336                 atomic_inc(&oldmm->mm_users);
 337                 mm = oldmm;
 338                 goto good_mm;
 339         }
 340
 341         retval = -ENOMEM;
 342         mm = allocate_mm();
 343         if (!mm)
 344                 goto fail_nomem;
 345
 346         /* Copy the current MM stuff.. */
 347         memcpy(mm, oldmm, sizeof(*mm));
 348         if (!mm_init(mm))
 349                 goto fail_nomem;
 350
 351         if (init_new_context(tsk,mm))
 352                 goto free_pt;
 353
 354         down_write(&oldmm->mmap_sem);
 355         retval = dup_mmap(mm);
 356         up_write(&oldmm->mmap_sem);
 357
 358         if (retval)
 359                 goto free_pt;
 360
 361         /*
 362          * child gets a private LDT (if there was an LDT in the parent)
 363          */
 364         copy_segments(tsk, mm);
 365
 366 good_mm:
 367         tsk->mm = mm;
 368         tsk->active_mm = mm;
 369         return 0;
 370
 371 free_pt:
 372         mmput(mm);
 373 fail_nomem:
 374         return retval;
 375 }
 376
 377 static inline struct fs_struct *__copy_fs_struct(struct fs_struct *old)
 378 {
 379         struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
 380         /* We don't need to lock fs - think why ;-) */
 381         if (fs) {
 382                 atomic_set(&fs->count, 1);
 383                 fs->lock = RW_LOCK_UNLOCKED;
 384                 fs->umask = old->umask;
 385                 read_lock(&old->lock);
 386                 fs->rootmnt = mntget(old->rootmnt);
 387                 fs->root = dget(old->root);
 388                 fs->pwdmnt = mntget(old->pwdmnt);
 389                 fs->pwd = dget(old->pwd);
 390                 if (old->altroot) {
 391                         fs->altrootmnt = mntget(old->altrootmnt);
 392                         fs->altroot = dget(old->altroot);
 393                 } else {
 394                         fs->altrootmnt = NULL;
 395                         fs->altroot = NULL;
 396                 }
 397                 read_unlock(&old->lock);
 398         }
 399         return fs;
 400 }
 401
 402 struct fs_struct *copy_fs_struct(struct fs_struct *old)
 403 {
 404         return __copy_fs_struct(old);
 405 }
 406
 407 static inline int copy_fs(unsigned long clone_flags, struct task_struct * tsk)
 408 {
 409         if (clone_flags & CLONE_FS) {
 410                 atomic_inc(&current->fs->count);
 411                 return 0;
 412         }
 413         tsk->fs = __copy_fs_struct(current->fs);
 414         if (!tsk->fs)
 415                 return -1;
 416         return 0;
 417 }
 418
 419 static int count_open_files(struct files_struct *files, int size)
 420 {
 421         int i;
 422
 423         /* Find the last open fd */
 424         for (i = size/(8*sizeof(long)); i > 0; ) {
 425                 if (files->open_fds->fds_bits[--i])
 426                         break;
 427         }
 428         i = (i+1) * 8 * sizeof(long);
 429         return i;
 430 }
 431
 432 static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
 433 {
 434         struct files_struct *oldf, *newf;
 435         struct file **old_fds, **new_fds;
 436         int open_files, nfds, size, i, error = 0;
 437
 438         /*
 439          * A background process may not have any files ...
 440          */
 441         oldf = current->files;
 442         if (!oldf)
 443                 goto out;
 444
 445         if (clone_flags & CLONE_FILES) {
 446                 atomic_inc(&oldf->count);
 447                 goto out;
 448         }
 449
 450         tsk->files = NULL;
 451         error = -ENOMEM;
 452         newf = kmem_cache_alloc(files_cachep, SLAB_KERNEL);
 453         if (!newf)
 454                 goto out;
 455
 456         atomic_set(&newf->count, 1);
 457
 458         newf->file_lock     = RW_LOCK_UNLOCKED;
 459         newf->next_fd       = 0;
 460         newf->max_fds       = NR_OPEN_DEFAULT;
 461         newf->max_fdset     = __FD_SETSIZE;
 462         newf->close_on_exec = &newf->close_on_exec_init;
 463         newf->open_fds      = &newf->open_fds_init;
 464         newf->fd            = &newf->fd_array[0];
 465
 466         /* We don't yet have the oldf readlock, but even if the old
 467            fdset gets grown now, we'll only copy up to "size" fds */
 468         size = oldf->max_fdset;
 469         if (size > __FD_SETSIZE) {
 470                 newf->max_fdset = 0;
 471                 write_lock(&newf->file_lock);
 472                 error = expand_fdset(newf, size-1);
 473                 write_unlock(&newf->file_lock);
 474                 if (error)
 475                         goto out_release;
 476         }
 477         read_lock(&oldf->file_lock);
 478
 479         open_files = count_open_files(oldf, size);
 480
 481         /*
 482          * Check whether we need to allocate a larger fd array.
 483          * Note: we're not a clone task, so the open count won't
 484          * change.
 485          */
 486         nfds = NR_OPEN_DEFAULT;
 487         if (open_files > nfds) {
 488                 read_unlock(&oldf->file_lock);
 489                 newf->max_fds = 0;
 490                 write_lock(&newf->file_lock);
 491                 error = expand_fd_array(newf, open_files-1);
 492                 write_unlock(&newf->file_lock);
 493                 if (error)
 494                         goto out_release;
 495                 nfds = newf->max_fds;
 496                 read_lock(&oldf->file_lock);
 497         }
 498
 499         old_fds = oldf->fd;
 500         new_fds = newf->fd;
 501
 502         memcpy(newf->open_fds->fds_bits, oldf->open_fds->fds_bits, open_files/8);
 503         memcpy(newf->close_on_exec->fds_bits, oldf->close_on_exec->fds_bits, open_files/8);
 504
 505         for (i = open_files; i != 0; i--) {
 506                 struct file *f = *old_fds++;
 507                 if (f)
 508                         get_file(f);
 509                 *new_fds++ = f;
 510         }
 511         read_unlock(&oldf->file_lock);
 512
 513         /* compute the remainder to be cleared */
 514         size = (newf->max_fds - open_files) * sizeof(struct file *);
 515
 516         /* This is long word aligned thus could use a optimized version */
 517         memset(new_fds, 0, size);
 518
 519         if (newf->max_fdset > open_files) {
 520                 int left = (newf->max_fdset-open_files)/8;
 521                 int start = open_files / (8 * sizeof(unsigned long));
 522
 523                 memset(&newf->open_fds->fds_bits[start], 0, left);
 524                 memset(&newf->close_on_exec->fds_bits[start], 0, left);
 525         }
 526
 527         tsk->files = newf;
 528         error = 0;
 529 out:
 530         return error;
 531
 532 out_release:
 533         free_fdset (newf->close_on_exec, newf->max_fdset);
 534         free_fdset (newf->open_fds, newf->max_fdset);
 535         kmem_cache_free(files_cachep, newf);
 536         goto out;
 537 }
 538
 539 static inline int copy_sighand(unsigned long clone_flags, struct task_struct * tsk)
 540 {
 541         struct signal_struct *sig;
 542
 543         if (clone_flags & CLONE_SIGHAND) {
 544                 atomic_inc(&current->sig->count);
 545                 return 0;
 546         }
 547         sig = kmem_cache_alloc(sigact_cachep, GFP_KERNEL);
 548         tsk->sig = sig;
 549         if (!sig)
 550                 return -1;
 551         spin_lock_init(&sig->siglock);
 552         atomic_set(&sig->count, 1);
 553         memcpy(tsk->sig->action, current->sig->action, sizeof(tsk->sig->action));
 554         return 0;
 555 }
 556
 557 static inline void copy_flags(unsigned long clone_flags, struct task_struct *p)
 558 {
 559         unsigned long new_flags = p->flags;
 560
 561         new_flags &= ~(PF_SUPERPRIV | PF_USEDFPU);
 562         new_flags |= PF_FORKNOEXEC;
 563         if (!(clone_flags & CLONE_PTRACE))
 564                 p->ptrace = 0;
 565         p->flags = new_flags;
 566 }
 567
 568 /*
 569  *  Ok, this is the main fork-routine. It copies the system process
 570  * information (task[nr]) and sets up the necessary registers. It also
 571  * copies the data segment in its entirety.  The "stack_start" and
 572  * "stack_top" arguments are simply passed along to the platform
 573  * specific copy_thread() routine.  Most platforms ignore stack_top.
 574  * For an example that's using stack_top, see
 575  * arch/ia64/kernel/process.c.
 576  */
 577 int do_fork(unsigned long clone_flags, unsigned long stack_start,
 578             struct pt_regs *regs, unsigned long stack_size)
 579 {
 580         int retval;
 581         struct task_struct *p;
 582         struct completion vfork;
 583
 584         if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
 585                 return -EINVAL;
 586
 587         retval = -EPERM;
 588
 589         /*
 590          * CLONE_PID is only allowed for the initial SMP swapper
 591          * calls
 592          */
 593         if (clone_flags & CLONE_PID) {
 594                 if (current->pid)
 595                         goto fork_out;
 596         }
 597
 598         retval = -ENOMEM;
 599         p = alloc_task_struct();
 600         if (!p)
 601                 goto fork_out;
 602
 603         *p = *current;
 604
 605         retval = -EAGAIN;
 606         /*
 607          * Check if we are over our maximum process limit, but be sure to
 608          * exclude root. This is needed to make it possible for login and
 609          * friends to set the per-user process limit to something lower
 610          * than the amount of processes root is running. -- Rik
 611          */
 612         if (atomic_read(&p->user->processes) >= p->rlim[RLIMIT_NPROC].rlim_cur
 613                       && !capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE))
 614                 goto bad_fork_free;
 615
 616         atomic_inc(&p->user->__count);
 617         atomic_inc(&p->user->processes);
 618
 619         /*
 620          * Counter increases are protected by
 621          * the kernel lock so nr_threads can't
 622          * increase under us (but it may decrease).
 623          */
 624         if (nr_threads >= max_threads)
 625                 goto bad_fork_cleanup_count;
 626
 627         get_exec_domain(p->exec_domain);
 628
 629         if (p->binfmt && p->binfmt->module)
 630                 __MOD_INC_USE_COUNT(p->binfmt->module);
 631
 632         p->did_exec = 0;
 633         p->swappable = 0;
 634         p->state = TASK_UNINTERRUPTIBLE;
 635
 636         copy_flags(clone_flags, p);
 637         p->pid = get_pid(clone_flags);
 638         if (p->pid == 0 && current->pid != 0)
 639                 goto bad_fork_cleanup;
 640
 641         p->run_list.next = NULL;
 642         p->run_list.prev = NULL;
 643
 644         p->p_cptr = NULL;
 645         init_waitqueue_head(&p->wait_chldexit);
 646         p->vfork_done = NULL;
 647         if (clone_flags & CLONE_VFORK) {
 648                 p->vfork_done = &vfork;
 649                 init_completion(&vfork);
 650         }
 651         spin_lock_init(&p->alloc_lock);
 652
 653         p->sigpending = 0;
 654         init_sigpending(&p->pending);
 655
 656         p->it_real_value = p->it_virt_value = p->it_prof_value = 0;
 657         p->it_real_incr = p->it_virt_incr = p->it_prof_incr = 0;
 658         init_timer(&p->real_timer);
 659         p->real_timer.data = (unsigned long) p;
 660
 661         p->leader = 0;          /* session leadership doesn't inherit */
 662         p->tty_old_pgrp = 0;
 663         p->times.tms_utime = p->times.tms_stime = 0;
 664         p->times.tms_cutime = p->times.tms_cstime = 0;
 665 #ifdef CONFIG_SMP
 666         {
 667                 int i;
 668                 p->cpus_runnable = ~0UL;
 669                 p->processor = current->processor;
 670                 /* ?? should we just memset this ?? */
 671                 for(i = 0; i < smp_num_cpus; i++)
 672                         p->per_cpu_utime[i] = p->per_cpu_stime[i] = 0;
 673                 spin_lock_init(&p->sigmask_lock);
 674         }
 675 #endif
 676         p->lock_depth = -1;             /* -1 = no lock */
 677         p->start_time = jiffies;
 678
 679         INIT_LIST_HEAD(&p->local_pages);
 680
 681         retval = -ENOMEM;
 682         /* copy all the process information */
 683         if (copy_files(clone_flags, p))
 684                 goto bad_fork_cleanup;
 685         if (copy_fs(clone_flags, p))
 686                 goto bad_fork_cleanup_files;
 687         if (copy_sighand(clone_flags, p))
 688                 goto bad_fork_cleanup_fs;
 689         if (copy_mm(clone_flags, p))
 690                 goto bad_fork_cleanup_sighand;
 691         if (copy_namespace(clone_flags, p))
 692                 goto bad_fork_cleanup_mm;
 693         retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
 694         if (retval)
 695                 goto bad_fork_cleanup_namespace;
 696         p->semundo = NULL;
 697
 698         /* Our parent execution domain becomes current domain
 699            These must match for thread signalling to apply */
 700
 701         p->parent_exec_id = p->self_exec_id;
 702
 703         /* ok, now we should be set up.. */
 704         p->swappable = 1;
 705         p->exit_signal = clone_flags & CSIGNAL;
 706         p->pdeath_signal = 0;
 707
 708         /*
 709          * "share" dynamic priority between parent and child, thus the
 710          * total amount of dynamic priorities in the system doesn't change,
 711          * more scheduling fairness. This is only important in the first
 712          * timeslice, on the long run the scheduling behaviour is unchanged.
 713          */
 714         p->counter = (current->counter + 1) >> 1;
 715         current->counter >>= 1;
 716         if (!current->counter)
 717                 current->need_resched = 1;
 718
 719         /*
 720          * Ok, add it to the run-queues and make it
 721          * visible to the rest of the system.
 722          *
 723          * Let it rip!
 724          */
 725         retval = p->pid;
 726         p->tgid = retval;
 727         INIT_LIST_HEAD(&p->thread_group);
 728
 729         /* Need tasklist lock for parent etc handling! */
 730         write_lock_irq(&tasklist_lock);
 731
 732         /* CLONE_PARENT re-uses the old parent */
 733         p->p_opptr = current->p_opptr;
 734         p->p_pptr = current->p_pptr;
 735         if (!(clone_flags & CLONE_PARENT)) {
 736                 p->p_opptr = current;
 737                 if (!(p->ptrace & PT_PTRACED))
 738                         p->p_pptr = current;
 739         }
 740
 741         if (clone_flags & CLONE_THREAD) {
 742                 p->tgid = current->tgid;
 743                 list_add(&p->thread_group, &current->thread_group);
 744         }
 745
 746         SET_LINKS(p);
 747         hash_pid(p);
 748         nr_threads++;
 749         write_unlock_irq(&tasklist_lock);
 750
 751         if (p->ptrace & PT_PTRACED)
 752                 send_sig(SIGSTOP, p, 1);
 753
 754         wake_up_process(p);             /* do this last */
 755         ++total_forks;
 756         if (clone_flags & CLONE_VFORK)
 757                 wait_for_completion(&vfork);
 758
 759 fork_out:
 760         return retval;
 761
 762 bad_fork_cleanup_namespace:
 763         exit_namespace(p);
 764 bad_fork_cleanup_mm:
 765         exit_mm(p);
 766 bad_fork_cleanup_sighand:
 767         exit_sighand(p);
 768 bad_fork_cleanup_fs:
 769         exit_fs(p); /* blocking */
 770 bad_fork_cleanup_files:
 771         exit_files(p); /* blocking */
 772 bad_fork_cleanup:
 773         put_exec_domain(p->exec_domain);
 774         if (p->binfmt && p->binfmt->module)
 775                 __MOD_DEC_USE_COUNT(p->binfmt->module);
 776 bad_fork_cleanup_count:
 777         atomic_dec(&p->user->processes);
 778         free_uid(p->user);
 779 bad_fork_free:
 780         free_task_struct(p);
 781         goto fork_out;
 782 }
 783
 784 /* SLAB cache for signal_struct structures (tsk->sig) */
 785 kmem_cache_t *sigact_cachep;
 786
 787 /* SLAB cache for files_struct structures (tsk->files) */
 788 kmem_cache_t *files_cachep;
 789
 790 /* SLAB cache for fs_struct structures (tsk->fs) */
 791 kmem_cache_t *fs_cachep;
 792
 793 /* SLAB cache for vm_area_struct structures */
 794 kmem_cache_t *vm_area_cachep;
 795
 796 /* SLAB cache for mm_struct structures (tsk->mm) */
 797 kmem_cache_t *mm_cachep;
 798
 799 void __init proc_caches_init(void)
 800 {
 801         sigact_cachep = kmem_cache_create("signal_act",
 802                         sizeof(struct signal_struct), 0,
 803                         SLAB_HWCACHE_ALIGN, NULL, NULL);
 804         if (!sigact_cachep)
 805                 panic("Cannot create signal action SLAB cache");
 806
 807         files_cachep = kmem_cache_create("files_cache",
 808                          sizeof(struct files_struct), 0,
 809                          SLAB_HWCACHE_ALIGN, NULL, NULL);
 810         if (!files_cachep)
 811                 panic("Cannot create files SLAB cache");
 812
 813         fs_cachep = kmem_cache_create("fs_cache",
 814                          sizeof(struct fs_struct), 0,
 815                          SLAB_HWCACHE_ALIGN, NULL, NULL);
 816         if (!fs_cachep)
 817                 panic("Cannot create fs_struct SLAB cache");
 818
 819         vm_area_cachep = kmem_cache_create("vm_area_struct",
 820                         sizeof(struct vm_area_struct), 0,
 821                         SLAB_HWCACHE_ALIGN, NULL, NULL);
 822         if(!vm_area_cachep)
 823                 panic("vma_init: Cannot alloc vm_area_struct SLAB cache");
 824
 825         mm_cachep = kmem_cache_create("mm_struct",
 826                         sizeof(struct mm_struct), 0,
 827                         SLAB_HWCACHE_ALIGN, NULL, NULL);
 828         if(!mm_cachep)
 829                 panic("vma_init: Cannot alloc mm_struct SLAB cache");
 830 }