fork.c 40.7 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
/*
 *  linux/kernel/fork.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

/*
 *  'fork.c' contains the help-routines for the 'fork' system call
 * (see also entry.S and others).
 * Fork is rather simple, once you get the hang of it, but the memory
 * management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
 */

#include <linux/slab.h>
#include <linux/init.h>
#include <linux/unistd.h>
#include <linux/module.h>
#include <linux/vmalloc.h>
#include <linux/completion.h>
20
#include <linux/mnt_namespace.h>
Linus Torvalds's avatar
Linus Torvalds committed
21 22 23 24
#include <linux/personality.h>
#include <linux/mempolicy.h>
#include <linux/sem.h>
#include <linux/file.h>
Al Viro's avatar
Al Viro committed
25
#include <linux/fdtable.h>
26
#include <linux/iocontext.h>
Linus Torvalds's avatar
Linus Torvalds committed
27 28 29 30
#include <linux/key.h>
#include <linux/binfmts.h>
#include <linux/mman.h>
#include <linux/fs.h>
31
#include <linux/nsproxy.h>
32
#include <linux/capability.h>
Linus Torvalds's avatar
Linus Torvalds committed
33
#include <linux/cpu.h>
34
#include <linux/cgroup.h>
Linus Torvalds's avatar
Linus Torvalds committed
35
#include <linux/security.h>
36
#include <linux/hugetlb.h>
Linus Torvalds's avatar
Linus Torvalds committed
37 38 39 40
#include <linux/swap.h>
#include <linux/syscalls.h>
#include <linux/jiffies.h>
#include <linux/futex.h>
41
#include <linux/task_io_accounting_ops.h>
42
#include <linux/rcupdate.h>
Linus Torvalds's avatar
Linus Torvalds committed
43 44 45
#include <linux/ptrace.h>
#include <linux/mount.h>
#include <linux/audit.h>
46
#include <linux/memcontrol.h>
Linus Torvalds's avatar
Linus Torvalds committed
47 48 49
#include <linux/profile.h>
#include <linux/rmap.h>
#include <linux/acct.h>
50
#include <linux/tsacct_kern.h>
51
#include <linux/cn_proc.h>
52
#include <linux/freezer.h>
53
#include <linux/delayacct.h>
54
#include <linux/taskstats_kern.h>
55
#include <linux/random.h>
56
#include <linux/tty.h>
57
#include <linux/proc_fs.h>
58
#include <linux/blkdev.h>
Linus Torvalds's avatar
Linus Torvalds committed
59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76

#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/uaccess.h>
#include <asm/mmu_context.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>

/*
 * Protected counters by write_lock_irq(&tasklist_lock)
 */
unsigned long total_forks;	/* Handle normal Linux uptimes. */
int nr_threads; 		/* The idle threads do not count.. */

int max_threads;		/* tunable limit on nr_threads */

DEFINE_PER_CPU(unsigned long, process_counts) = 0;

77
__cacheline_aligned DEFINE_RWLOCK(tasklist_lock);  /* outer */
Linus Torvalds's avatar
Linus Torvalds committed
78 79 80 81 82 83 84 85 86 87 88 89 90 91 92

int nr_processes(void)
{
	int cpu;
	int total = 0;

	for_each_online_cpu(cpu)
		total += per_cpu(process_counts, cpu);

	return total;
}

#ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
# define alloc_task_struct()	kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
# define free_task_struct(tsk)	kmem_cache_free(task_struct_cachep, (tsk))
93
static struct kmem_cache *task_struct_cachep;
Linus Torvalds's avatar
Linus Torvalds committed
94 95 96
#endif

/* SLAB cache for signal_struct structures (tsk->signal) */
97
static struct kmem_cache *signal_cachep;
Linus Torvalds's avatar
Linus Torvalds committed
98 99

/* SLAB cache for sighand_struct structures (tsk->sighand) */
100
struct kmem_cache *sighand_cachep;
Linus Torvalds's avatar
Linus Torvalds committed
101 102

/* SLAB cache for files_struct structures (tsk->files) */
103
struct kmem_cache *files_cachep;
Linus Torvalds's avatar
Linus Torvalds committed
104 105

/* SLAB cache for fs_struct structures (tsk->fs) */
106
struct kmem_cache *fs_cachep;
Linus Torvalds's avatar
Linus Torvalds committed
107 108

/* SLAB cache for vm_area_struct structures */
109
struct kmem_cache *vm_area_cachep;
Linus Torvalds's avatar
Linus Torvalds committed
110 111

/* SLAB cache for mm_struct structures (tsk->mm) */
112
static struct kmem_cache *mm_cachep;
Linus Torvalds's avatar
Linus Torvalds committed
113 114 115

void free_task(struct task_struct *tsk)
{
116
	prop_local_destroy_single(&tsk->dirties);
Roman Zippel's avatar
Roman Zippel committed
117
	free_thread_info(tsk->stack);
118
	rt_mutex_debug_task_free(tsk);
Linus Torvalds's avatar
Linus Torvalds committed
119 120 121 122
	free_task_struct(tsk);
}
EXPORT_SYMBOL(free_task);

123
void __put_task_struct(struct task_struct *tsk)
Linus Torvalds's avatar
Linus Torvalds committed
124
{
Eugene Teo's avatar
Eugene Teo committed
125
	WARN_ON(!tsk->exit_state);
Linus Torvalds's avatar
Linus Torvalds committed
126 127 128 129 130 131
	WARN_ON(atomic_read(&tsk->usage));
	WARN_ON(tsk == current);

	security_task_free(tsk);
	free_uid(tsk->user);
	put_group_info(tsk->group_info);
132
	delayacct_tsk_free(tsk);
Linus Torvalds's avatar
Linus Torvalds committed
133 134 135 136 137

	if (!profile_handoff_task(tsk))
		free_task(tsk);
}

Suresh Siddha's avatar
Suresh Siddha committed
138 139 140 141 142 143 144
/*
 * macro override instead of weak attribute alias, to workaround
 * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions.
 */
#ifndef arch_task_cache_init
#define arch_task_cache_init()
#endif
145

Linus Torvalds's avatar
Linus Torvalds committed
146 147 148 149 150 151 152 153 154
void __init fork_init(unsigned long mempages)
{
#ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
#ifndef ARCH_MIN_TASKALIGN
#define ARCH_MIN_TASKALIGN	L1_CACHE_BYTES
#endif
	/* create a slab on which task_structs can be allocated */
	task_struct_cachep =
		kmem_cache_create("task_struct", sizeof(struct task_struct),
155
			ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL);
Linus Torvalds's avatar
Linus Torvalds committed
156 157
#endif

158 159 160
	/* do the arch specific task caches init */
	arch_task_cache_init();

Linus Torvalds's avatar
Linus Torvalds committed
161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179
	/*
	 * The default maximum number of threads is set to a safe
	 * value: the thread structures can take up at most half
	 * of memory.
	 */
	max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);

	/*
	 * we need to allow at least 20 threads to boot a system
	 */
	if(max_threads < 20)
		max_threads = 20;

	init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
	init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
	init_task.signal->rlim[RLIMIT_SIGPENDING] =
		init_task.signal->rlim[RLIMIT_NPROC];
}

180 181 182 183 184 185 186
int __attribute__((weak)) arch_dup_task_struct(struct task_struct *dst,
					       struct task_struct *src)
{
	*dst = *src;
	return 0;
}

Linus Torvalds's avatar
Linus Torvalds committed
187 188 189 190
static struct task_struct *dup_task_struct(struct task_struct *orig)
{
	struct task_struct *tsk;
	struct thread_info *ti;
191
	int err;
Linus Torvalds's avatar
Linus Torvalds committed
192 193 194 195 196 197 198 199 200 201 202 203 204

	prepare_to_copy(orig);

	tsk = alloc_task_struct();
	if (!tsk)
		return NULL;

	ti = alloc_thread_info(tsk);
	if (!ti) {
		free_task_struct(tsk);
		return NULL;
	}

205 206 207 208
 	err = arch_dup_task_struct(tsk, orig);
	if (err)
		goto out;

Roman Zippel's avatar
Roman Zippel committed
209
	tsk->stack = ti;
210 211

	err = prop_local_init_single(&tsk->dirties);
212 213
	if (err)
		goto out;
214

215
	setup_thread_stack(tsk, orig);
Linus Torvalds's avatar
Linus Torvalds committed
216

217 218 219 220
#ifdef CONFIG_CC_STACKPROTECTOR
	tsk->stack_canary = get_random_int();
#endif

Linus Torvalds's avatar
Linus Torvalds committed
221 222
	/* One for us, one for whoever does the "release_task()" (usually parent) */
	atomic_set(&tsk->usage,2);
223
	atomic_set(&tsk->fs_excl, 0);
224
#ifdef CONFIG_BLK_DEV_IO_TRACE
225
	tsk->btrace_seq = 0;
226
#endif
227
	tsk->splice_pipe = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
228
	return tsk;
229 230 231 232 233

out:
	free_thread_info(ti);
	free_task_struct(tsk);
	return NULL;
Linus Torvalds's avatar
Linus Torvalds committed
234 235 236
}

#ifdef CONFIG_MMU
Alexey Dobriyan's avatar
Alexey Dobriyan committed
237
static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
Linus Torvalds's avatar
Linus Torvalds committed
238
{
239
	struct vm_area_struct *mpnt, *tmp, **pprev;
Linus Torvalds's avatar
Linus Torvalds committed
240 241 242 243 244 245
	struct rb_node **rb_link, *rb_parent;
	int retval;
	unsigned long charge;
	struct mempolicy *pol;

	down_write(&oldmm->mmap_sem);
246
	flush_cache_dup_mm(oldmm);
247 248 249 250
	/*
	 * Not linked in yet - no deadlock potential:
	 */
	down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
251

Linus Torvalds's avatar
Linus Torvalds committed
252 253 254 255
	mm->locked_vm = 0;
	mm->mmap = NULL;
	mm->mmap_cache = NULL;
	mm->free_area_cache = oldmm->mmap_base;
256
	mm->cached_hole_size = ~0UL;
Linus Torvalds's avatar
Linus Torvalds committed
257 258 259 260 261 262 263
	mm->map_count = 0;
	cpus_clear(mm->cpu_vm_mask);
	mm->mm_rb = RB_ROOT;
	rb_link = &mm->mm_rb.rb_node;
	rb_parent = NULL;
	pprev = &mm->mmap;

264
	for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
Linus Torvalds's avatar
Linus Torvalds committed
265 266 267
		struct file *file;

		if (mpnt->vm_flags & VM_DONTCOPY) {
268 269
			long pages = vma_pages(mpnt);
			mm->total_vm -= pages;
270
			vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
271
								-pages);
Linus Torvalds's avatar
Linus Torvalds committed
272 273 274 275 276 277 278 279 280
			continue;
		}
		charge = 0;
		if (mpnt->vm_flags & VM_ACCOUNT) {
			unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
			if (security_vm_enough_memory(len))
				goto fail_nomem;
			charge = len;
		}
281
		tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
Linus Torvalds's avatar
Linus Torvalds committed
282 283 284
		if (!tmp)
			goto fail_nomem;
		*tmp = *mpnt;
285
		pol = mpol_dup(vma_policy(mpnt));
Linus Torvalds's avatar
Linus Torvalds committed
286 287 288 289 290 291 292 293 294 295
		retval = PTR_ERR(pol);
		if (IS_ERR(pol))
			goto fail_nomem_policy;
		vma_set_policy(tmp, pol);
		tmp->vm_flags &= ~VM_LOCKED;
		tmp->vm_mm = mm;
		tmp->vm_next = NULL;
		anon_vma_link(tmp);
		file = tmp->vm_file;
		if (file) {
296
			struct inode *inode = file->f_path.dentry->d_inode;
Linus Torvalds's avatar
Linus Torvalds committed
297 298 299
			get_file(file);
			if (tmp->vm_flags & VM_DENYWRITE)
				atomic_dec(&inode->i_writecount);
Daniel Walker's avatar
Daniel Walker committed
300

Linus Torvalds's avatar
Linus Torvalds committed
301 302 303 304 305 306 307 308 309
			/* insert tmp into the share list, just after mpnt */
			spin_lock(&file->f_mapping->i_mmap_lock);
			tmp->vm_truncate_count = mpnt->vm_truncate_count;
			flush_dcache_mmap_lock(file->f_mapping);
			vma_prio_tree_add(tmp, mpnt);
			flush_dcache_mmap_unlock(file->f_mapping);
			spin_unlock(&file->f_mapping->i_mmap_lock);
		}

310 311 312 313 314 315 316 317
		/*
		 * Clear hugetlb-related page reserves for children. This only
		 * affects MAP_PRIVATE mappings. Faults generated by the child
		 * are not guaranteed to succeed, even if read-only
		 */
		if (is_vm_hugetlb_page(tmp))
			reset_vma_resv_huge_pages(tmp);

Linus Torvalds's avatar
Linus Torvalds committed
318
		/*
319
		 * Link in the new vma and copy the page table entries.
Linus Torvalds's avatar
Linus Torvalds committed
320 321 322 323 324 325 326 327 328
		 */
		*pprev = tmp;
		pprev = &tmp->vm_next;

		__vma_link_rb(mm, tmp, rb_link, rb_parent);
		rb_link = &tmp->vm_rb.rb_right;
		rb_parent = &tmp->vm_rb;

		mm->map_count++;
329
		retval = copy_page_range(mm, oldmm, mpnt);
Linus Torvalds's avatar
Linus Torvalds committed
330 331 332 333 334 335 336

		if (tmp->vm_ops && tmp->vm_ops->open)
			tmp->vm_ops->open(tmp);

		if (retval)
			goto out;
	}
337 338
	/* a new mm has just been created */
	arch_dup_mmap(oldmm, mm);
Linus Torvalds's avatar
Linus Torvalds committed
339 340
	retval = 0;
out:
341
	up_write(&mm->mmap_sem);
342
	flush_tlb_mm(oldmm);
Linus Torvalds's avatar
Linus Torvalds committed
343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362
	up_write(&oldmm->mmap_sem);
	return retval;
fail_nomem_policy:
	kmem_cache_free(vm_area_cachep, tmp);
fail_nomem:
	retval = -ENOMEM;
	vm_unacct_memory(charge);
	goto out;
}

static inline int mm_alloc_pgd(struct mm_struct * mm)
{
	mm->pgd = pgd_alloc(mm);
	if (unlikely(!mm->pgd))
		return -ENOMEM;
	return 0;
}

static inline void mm_free_pgd(struct mm_struct * mm)
{
363
	pgd_free(mm, mm->pgd);
Linus Torvalds's avatar
Linus Torvalds committed
364 365 366 367 368 369 370
}
#else
#define dup_mmap(mm, oldmm)	(0)
#define mm_alloc_pgd(mm)	(0)
#define mm_free_pgd(mm)
#endif /* CONFIG_MMU */

Daniel Walker's avatar
Daniel Walker committed
371
__cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
Linus Torvalds's avatar
Linus Torvalds committed
372

373
#define allocate_mm()	(kmem_cache_alloc(mm_cachep, GFP_KERNEL))
Linus Torvalds's avatar
Linus Torvalds committed
374 375 376 377
#define free_mm(mm)	(kmem_cache_free(mm_cachep, (mm)))

#include <linux/init_task.h>

378
static struct mm_struct * mm_init(struct mm_struct * mm, struct task_struct *p)
Linus Torvalds's avatar
Linus Torvalds committed
379 380 381 382 383
{
	atomic_set(&mm->mm_users, 1);
	atomic_set(&mm->mm_count, 1);
	init_rwsem(&mm->mmap_sem);
	INIT_LIST_HEAD(&mm->mmlist);
384 385
	mm->flags = (current->mm) ? current->mm->flags
				  : MMF_DUMP_FILTER_DEFAULT;
Linus Torvalds's avatar
Linus Torvalds committed
386 387
	mm->core_waiters = 0;
	mm->nr_ptes = 0;
388
	set_mm_counter(mm, file_rss, 0);
389
	set_mm_counter(mm, anon_rss, 0);
Linus Torvalds's avatar
Linus Torvalds committed
390 391 392 393
	spin_lock_init(&mm->page_table_lock);
	rwlock_init(&mm->ioctx_list_lock);
	mm->ioctx_list = NULL;
	mm->free_area_cache = TASK_UNMAPPED_BASE;
394
	mm->cached_hole_size = ~0UL;
395
	mm_init_owner(mm, p);
Linus Torvalds's avatar
Linus Torvalds committed
396 397 398 399 400

	if (likely(!mm_alloc_pgd(mm))) {
		mm->def_flags = 0;
		return mm;
	}
401

Linus Torvalds's avatar
Linus Torvalds committed
402 403 404 405 406 407 408 409 410 411 412 413 414 415
	free_mm(mm);
	return NULL;
}

/*
 * Allocate and initialize an mm_struct.
 */
struct mm_struct * mm_alloc(void)
{
	struct mm_struct * mm;

	mm = allocate_mm();
	if (mm) {
		memset(mm, 0, sizeof(*mm));
416
		mm = mm_init(mm, current);
Linus Torvalds's avatar
Linus Torvalds committed
417 418 419 420 421 422 423 424 425
	}
	return mm;
}

/*
 * Called when the last reference to the mm
 * is dropped: either by a lazy thread or by
 * mmput. Free the page directory and the mm.
 */
426
void __mmdrop(struct mm_struct *mm)
Linus Torvalds's avatar
Linus Torvalds committed
427 428 429 430 431 432
{
	BUG_ON(mm == &init_mm);
	mm_free_pgd(mm);
	destroy_context(mm);
	free_mm(mm);
}
433
EXPORT_SYMBOL_GPL(__mmdrop);
Linus Torvalds's avatar
Linus Torvalds committed
434 435 436 437 438 439

/*
 * Decrement the use count and release all resources for an mm.
 */
void mmput(struct mm_struct *mm)
{
Andrew Morton's avatar
Andrew Morton committed
440 441
	might_sleep();

Linus Torvalds's avatar
Linus Torvalds committed
442 443 444
	if (atomic_dec_and_test(&mm->mm_users)) {
		exit_aio(mm);
		exit_mmap(mm);
Matt Helsley's avatar
Matt Helsley committed
445
		set_mm_exe_file(mm, NULL);
Linus Torvalds's avatar
Linus Torvalds committed
446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507
		if (!list_empty(&mm->mmlist)) {
			spin_lock(&mmlist_lock);
			list_del(&mm->mmlist);
			spin_unlock(&mmlist_lock);
		}
		put_swap_token(mm);
		mmdrop(mm);
	}
}
EXPORT_SYMBOL_GPL(mmput);

/**
 * get_task_mm - acquire a reference to the task's mm
 *
 * Returns %NULL if the task has no mm.  Checks PF_BORROWED_MM (meaning
 * this kernel workthread has transiently adopted a user mm with use_mm,
 * to do its AIO) is not set and if so returns a reference to it, after
 * bumping up the use count.  User must release the mm via mmput()
 * after use.  Typically used by /proc and ptrace.
 */
struct mm_struct *get_task_mm(struct task_struct *task)
{
	struct mm_struct *mm;

	task_lock(task);
	mm = task->mm;
	if (mm) {
		if (task->flags & PF_BORROWED_MM)
			mm = NULL;
		else
			atomic_inc(&mm->mm_users);
	}
	task_unlock(task);
	return mm;
}
EXPORT_SYMBOL_GPL(get_task_mm);

/* Please note the differences between mmput and mm_release.
 * mmput is called whenever we stop holding onto a mm_struct,
 * error success whatever.
 *
 * mm_release is called after a mm_struct has been removed
 * from the current process.
 *
 * This difference is important for error handling, when we
 * only half set up a mm_struct for a new process and need to restore
 * the old one.  Because we mmput the new mm_struct before
 * restoring the old one. . .
 * Eric Biederman 10 January 1998
 */
void mm_release(struct task_struct *tsk, struct mm_struct *mm)
{
	struct completion *vfork_done = tsk->vfork_done;

	/* Get rid of any cached register state */
	deactivate_mm(tsk, mm);

	/* notify parent sleeping on vfork() */
	if (vfork_done) {
		tsk->vfork_done = NULL;
		complete(vfork_done);
	}
508 509 510 511 512 513 514 515 516 517

	/*
	 * If we're exiting normally, clear a user-space tid field if
	 * requested.  We leave this alone when dying by signal, to leave
	 * the value intact in a core dump, and to save the unnecessary
	 * trouble otherwise.  Userland only wants this done for a sys_exit.
	 */
	if (tsk->clear_child_tid
	    && !(tsk->flags & PF_SIGNALED)
	    && atomic_read(&mm->mm_users) > 1) {
Linus Torvalds's avatar
Linus Torvalds committed
518 519 520 521 522 523 524 525 526 527 528 529
		u32 __user * tidptr = tsk->clear_child_tid;
		tsk->clear_child_tid = NULL;

		/*
		 * We don't check the error code - if userspace has
		 * not set up a proper pointer then tough luck.
		 */
		put_user(0, tidptr);
		sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0);
	}
}

530 531 532 533
/*
 * Allocate a new mm structure and copy contents from the
 * mm structure of the passed in task structure.
 */
534
struct mm_struct *dup_mm(struct task_struct *tsk)
535 536 537 538 539 540 541 542 543 544 545 546 547
{
	struct mm_struct *mm, *oldmm = current->mm;
	int err;

	if (!oldmm)
		return NULL;

	mm = allocate_mm();
	if (!mm)
		goto fail_nomem;

	memcpy(mm, oldmm, sizeof(*mm));

548 549 550 551
	/* Initializing for Swap token stuff */
	mm->token_priority = 0;
	mm->last_interval = 0;

552
	if (!mm_init(mm, tsk))
553 554 555 556 557
		goto fail_nomem;

	if (init_new_context(tsk, mm))
		goto fail_nocontext;

Matt Helsley's avatar
Matt Helsley committed
558 559
	dup_mm_exe_file(oldmm, mm);

560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584
	err = dup_mmap(mm, oldmm);
	if (err)
		goto free_pt;

	mm->hiwater_rss = get_mm_rss(mm);
	mm->hiwater_vm = mm->total_vm;

	return mm;

free_pt:
	mmput(mm);

fail_nomem:
	return NULL;

fail_nocontext:
	/*
	 * If init_new_context() failed, we cannot use mmput() to free the mm
	 * because it calls destroy_context()
	 */
	mm_free_pgd(mm);
	free_mm(mm);
	return NULL;
}

Linus Torvalds's avatar
Linus Torvalds committed
585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611
static int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
{
	struct mm_struct * mm, *oldmm;
	int retval;

	tsk->min_flt = tsk->maj_flt = 0;
	tsk->nvcsw = tsk->nivcsw = 0;

	tsk->mm = NULL;
	tsk->active_mm = NULL;

	/*
	 * Are we cloning a kernel thread?
	 *
	 * We need to steal a active VM for that..
	 */
	oldmm = current->mm;
	if (!oldmm)
		return 0;

	if (clone_flags & CLONE_VM) {
		atomic_inc(&oldmm->mm_users);
		mm = oldmm;
		goto good_mm;
	}

	retval = -ENOMEM;
612
	mm = dup_mm(tsk);
Linus Torvalds's avatar
Linus Torvalds committed
613 614 615 616
	if (!mm)
		goto fail_nomem;

good_mm:
617 618 619 620
	/* Initializing for Swap token stuff */
	mm->token_priority = 0;
	mm->last_interval = 0;

Linus Torvalds's avatar
Linus Torvalds committed
621 622 623 624 625 626 627 628
	tsk->mm = mm;
	tsk->active_mm = mm;
	return 0;

fail_nomem:
	return retval;
}

Alexey Dobriyan's avatar
Alexey Dobriyan committed
629
static struct fs_struct *__copy_fs_struct(struct fs_struct *old)
Linus Torvalds's avatar
Linus Torvalds committed
630 631 632 633 634 635 636 637
{
	struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
	/* We don't need to lock fs - think why ;-) */
	if (fs) {
		atomic_set(&fs->count, 1);
		rwlock_init(&fs->lock);
		fs->umask = old->umask;
		read_lock(&old->lock);
Jan Blunck's avatar
Jan Blunck committed
638 639 640 641 642 643 644
		fs->root = old->root;
		path_get(&old->root);
		fs->pwd = old->pwd;
		path_get(&old->pwd);
		if (old->altroot.dentry) {
			fs->altroot = old->altroot;
			path_get(&old->altroot);
Linus Torvalds's avatar
Linus Torvalds committed
645
		} else {
Jan Blunck's avatar
Jan Blunck committed
646 647
			fs->altroot.mnt = NULL;
			fs->altroot.dentry = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
648 649 650 651 652 653 654 655 656 657 658 659 660
		}
		read_unlock(&old->lock);
	}
	return fs;
}

struct fs_struct *copy_fs_struct(struct fs_struct *old)
{
	return __copy_fs_struct(old);
}

EXPORT_SYMBOL_GPL(copy_fs_struct);

Alexey Dobriyan's avatar
Alexey Dobriyan committed
661
static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
Linus Torvalds's avatar
Linus Torvalds committed
662 663 664 665 666 667 668 669 670 671 672
{
	if (clone_flags & CLONE_FS) {
		atomic_inc(&current->fs->count);
		return 0;
	}
	tsk->fs = __copy_fs_struct(current->fs);
	if (!tsk->fs)
		return -ENOMEM;
	return 0;
}

673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699
static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
{
	struct files_struct *oldf, *newf;
	int error = 0;

	/*
	 * A background process may not have any files ...
	 */
	oldf = current->files;
	if (!oldf)
		goto out;

	if (clone_flags & CLONE_FILES) {
		atomic_inc(&oldf->count);
		goto out;
	}

	newf = dup_fd(oldf, &error);
	if (!newf)
		goto out;

	tsk->files = newf;
	error = 0;
out:
	return error;
}

700
static int copy_io(unsigned long clone_flags, struct task_struct *tsk)
701 702 703 704 705 706
{
#ifdef CONFIG_BLOCK
	struct io_context *ioc = current->io_context;

	if (!ioc)
		return 0;
707 708 709 710 711 712 713 714
	/*
	 * Share io context with parent, if CLONE_IO is set
	 */
	if (clone_flags & CLONE_IO) {
		tsk->io_context = ioc_task_link(ioc);
		if (unlikely(!tsk->io_context))
			return -ENOMEM;
	} else if (ioprio_valid(ioc->ioprio)) {
715 716 717 718 719 720 721 722 723 724
		tsk->io_context = alloc_io_context(GFP_KERNEL, -1);
		if (unlikely(!tsk->io_context))
			return -ENOMEM;

		tsk->io_context->ioprio = ioc->ioprio;
	}
#endif
	return 0;
}

Alexey Dobriyan's avatar
Alexey Dobriyan committed
725
static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
Linus Torvalds's avatar
Linus Torvalds committed
726 727 728 729 730 731 732 733
{
	struct sighand_struct *sig;

	if (clone_flags & (CLONE_SIGHAND | CLONE_THREAD)) {
		atomic_inc(&current->sighand->count);
		return 0;
	}
	sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
Ingo Molnar's avatar
Ingo Molnar committed
734
	rcu_assign_pointer(tsk->sighand, sig);
Linus Torvalds's avatar
Linus Torvalds committed
735 736 737 738 739 740 741
	if (!sig)
		return -ENOMEM;
	atomic_set(&sig->count, 1);
	memcpy(sig->action, current->sighand->action, sizeof(sig->action));
	return 0;
}

742
void __cleanup_sighand(struct sighand_struct *sighand)
743 744 745 746 747
{
	if (atomic_dec_and_test(&sighand->count))
		kmem_cache_free(sighand_cachep, sighand);
}

Alexey Dobriyan's avatar
Alexey Dobriyan committed
748
static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
Linus Torvalds's avatar
Linus Torvalds committed
749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775
{
	struct signal_struct *sig;
	int ret;

	if (clone_flags & CLONE_THREAD) {
		atomic_inc(&current->signal->count);
		atomic_inc(&current->signal->live);
		return 0;
	}
	sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
	tsk->signal = sig;
	if (!sig)
		return -ENOMEM;

	ret = copy_thread_group_keys(tsk);
	if (ret < 0) {
		kmem_cache_free(signal_cachep, sig);
		return ret;
	}

	atomic_set(&sig->count, 1);
	atomic_set(&sig->live, 1);
	init_waitqueue_head(&sig->wait_chldexit);
	sig->flags = 0;
	sig->group_exit_code = 0;
	sig->group_exit_task = NULL;
	sig->group_stop_count = 0;
776
	sig->curr_target = tsk;
Linus Torvalds's avatar
Linus Torvalds committed
777 778 779
	init_sigpending(&sig->shared_pending);
	INIT_LIST_HEAD(&sig->posix_timers);

780
	hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
781
	sig->it_real_incr.tv64 = 0;
Linus Torvalds's avatar
Linus Torvalds committed
782 783 784 785 786 787 788 789
	sig->real_timer.function = it_real_fn;

	sig->it_virt_expires = cputime_zero;
	sig->it_virt_incr = cputime_zero;
	sig->it_prof_expires = cputime_zero;
	sig->it_prof_incr = cputime_zero;

	sig->leader = 0;	/* session leadership doesn't inherit */
790
	sig->tty_old_pgrp = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
791 792

	sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero;
793 794
	sig->gtime = cputime_zero;
	sig->cgtime = cputime_zero;
Linus Torvalds's avatar
Linus Torvalds committed
795 796
	sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0;
	sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0;
797
	sig->inblock = sig->oublock = sig->cinblock = sig->coublock = 0;
798
	sig->sum_sched_runtime = 0;
Linus Torvalds's avatar
Linus Torvalds committed
799 800 801
	INIT_LIST_HEAD(&sig->cpu_timers[0]);
	INIT_LIST_HEAD(&sig->cpu_timers[1]);
	INIT_LIST_HEAD(&sig->cpu_timers[2]);
802
	taskstats_tgid_init(sig);
Linus Torvalds's avatar
Linus Torvalds committed
803 804 805 806 807 808 809 810 811 812 813 814 815

	task_lock(current->group_leader);
	memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
	task_unlock(current->group_leader);

	if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
		/*
		 * New sole thread in the process gets an expiry time
		 * of the whole CPU time limit.
		 */
		tsk->it_prof_expires =
			secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
	}
816
	acct_init_pacct(&sig->pacct);
Linus Torvalds's avatar
Linus Torvalds committed
817

818 819
	tty_audit_fork(sig);

Linus Torvalds's avatar
Linus Torvalds committed
820 821 822
	return 0;
}

823 824 825 826 827 828
void __cleanup_signal(struct signal_struct *sig)
{
	exit_thread_group_keys(sig);
	kmem_cache_free(signal_cachep, sig);
}

Alexey Dobriyan's avatar
Alexey Dobriyan committed
829
static void cleanup_signal(struct task_struct *tsk)
830 831 832 833 834 835 836 837 838
{
	struct signal_struct *sig = tsk->signal;

	atomic_dec(&sig->live);

	if (atomic_dec_and_test(&sig->count))
		__cleanup_signal(sig);
}

Alexey Dobriyan's avatar
Alexey Dobriyan committed
839
static void copy_flags(unsigned long clone_flags, struct task_struct *p)
Linus Torvalds's avatar
Linus Torvalds committed
840 841 842
{
	unsigned long new_flags = p->flags;

843
	new_flags &= ~PF_SUPERPRIV;
Linus Torvalds's avatar
Linus Torvalds committed
844 845 846 847
	new_flags |= PF_FORKNOEXEC;
	if (!(clone_flags & CLONE_PTRACE))
		p->ptrace = 0;
	p->flags = new_flags;
848
	clear_freeze_flag(p);
Linus Torvalds's avatar
Linus Torvalds committed
849 850 851 852 853 854
}

asmlinkage long sys_set_tid_address(int __user *tidptr)
{
	current->clear_child_tid = tidptr;

855
	return task_pid_vnr(current);
Linus Torvalds's avatar
Linus Torvalds committed
856 857
}

Alexey Dobriyan's avatar
Alexey Dobriyan committed
858
static void rt_mutex_init_task(struct task_struct *p)
859 860
{
	spin_lock_init(&p->pi_lock);
861
#ifdef CONFIG_RT_MUTEXES
862 863 864 865 866
	plist_head_init(&p->pi_waiters, &p->pi_lock);
	p->pi_blocked_on = NULL;
#endif
}

867 868 869 870 871 872 873
#ifdef CONFIG_MM_OWNER
void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
{
	mm->owner = p;
}
#endif /* CONFIG_MM_OWNER */

Linus Torvalds's avatar
Linus Torvalds committed
874 875 876 877 878 879 880 881
/*
 * This creates a new process as a copy of the old one,
 * but does not actually start it yet.
 *
 * It copies the registers, and all the appropriate
 * parts of the process environment (as per the clone
 * flags). The actual kick-off is left to the caller.
 */
882 883 884 885 886
static struct task_struct *copy_process(unsigned long clone_flags,
					unsigned long stack_start,
					struct pt_regs *regs,
					unsigned long stack_size,
					int __user *child_tidptr,
887
					struct pid *pid)
Linus Torvalds's avatar
Linus Torvalds committed
888 889
{
	int retval;
890
	struct task_struct *p;
891
	int cgroup_callbacks_done = 0;
Linus Torvalds's avatar
Linus Torvalds committed
892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919

	if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
		return ERR_PTR(-EINVAL);

	/*
	 * Thread groups must share signals as well, and detached threads
	 * can only be started up within the thread group.
	 */
	if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
		return ERR_PTR(-EINVAL);

	/*
	 * Shared signal handlers imply shared VM. By way of the above,
	 * thread groups also imply shared VM. Blocking this case allows
	 * for various simplifications in other code.
	 */
	if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
		return ERR_PTR(-EINVAL);

	retval = security_task_create(clone_flags);
	if (retval)
		goto fork_out;

	retval = -ENOMEM;
	p = dup_task_struct(current);
	if (!p)
		goto fork_out;

920 921
	rt_mutex_init_task(p);

922
#ifdef CONFIG_PROVE_LOCKING
923 924 925
	DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
	DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
#endif
Linus Torvalds's avatar
Linus Torvalds committed
926 927 928 929
	retval = -EAGAIN;
	if (atomic_read(&p->user->processes) >=
			p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
		if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
930
		    p->user != current->nsproxy->user_ns->root_user)
Linus Torvalds's avatar
Linus Torvalds committed
931 932 933 934 935 936 937 938 939 940 941 942 943 944 945
			goto bad_fork_free;
	}

	atomic_inc(&p->user->__count);
	atomic_inc(&p->user->processes);
	get_group_info(p->group_info);

	/*
	 * If multiple threads are within copy_process(), then this check
	 * triggers too late. This doesn't hurt, the check is only there
	 * to stop root fork bombs.
	 */
	if (nr_threads >= max_threads)
		goto bad_fork_cleanup_count;

946
	if (!try_module_get(task_thread_info(p)->exec_domain->module))
Linus Torvalds's avatar
Linus Torvalds committed
947 948 949 950 951 952
		goto bad_fork_cleanup_count;

	if (p->binfmt && !try_module_get(p->binfmt->module))
		goto bad_fork_cleanup_put_domain;

	p->did_exec = 0;
953
	delayacct_tsk_init(p);	/* Must remain after dup_task_struct() */
Linus Torvalds's avatar
Linus Torvalds committed
954 955 956
	copy_flags(clone_flags, p);
	INIT_LIST_HEAD(&p->children);
	INIT_LIST_HEAD(&p->sibling);
957 958 959 960
#ifdef CONFIG_PREEMPT_RCU
	p->rcu_read_lock_nesting = 0;
	p->rcu_flipctr_idx = 0;
#endif /* #ifdef CONFIG_PREEMPT_RCU */
Linus Torvalds's avatar
Linus Torvalds committed
961 962 963 964 965 966 967 968
	p->vfork_done = NULL;
	spin_lock_init(&p->alloc_lock);

	clear_tsk_thread_flag(p, TIF_SIGPENDING);
	init_sigpending(&p->pending);

	p->utime = cputime_zero;
	p->stime = cputime_zero;
969
	p->gtime = cputime_zero;
970 971
	p->utimescaled = cputime_zero;
	p->stimescaled = cputime_zero;
972
	p->prev_utime = cputime_zero;
973
	p->prev_stime = cputime_zero;
974

975 976 977 978 979
#ifdef CONFIG_DETECT_SOFTLOCKUP
	p->last_switch_count = 0;
	p->last_switch_timestamp = 0;
#endif

980
#ifdef CONFIG_TASK_XACCT
Linus Torvalds's avatar
Linus Torvalds committed
981 982 983 984
	p->rchar = 0;		/* I/O counter: bytes read */
	p->wchar = 0;		/* I/O counter: bytes written */
	p->syscr = 0;		/* I/O counter: read syscalls */
	p->syscw = 0;		/* I/O counter: write syscalls */
985
#endif
986
	task_io_accounting_init(p);
Linus Torvalds's avatar
Linus Torvalds committed
987 988
	acct_clear_integrals(p);

Daniel Walker's avatar
Daniel Walker committed
989
	p->it_virt_expires = cputime_zero;
Linus Torvalds's avatar
Linus Torvalds committed
990
	p->it_prof_expires = cputime_zero;
Daniel Walker's avatar
Daniel Walker committed
991 992 993 994
	p->it_sched_expires = 0;
	INIT_LIST_HEAD(&p->cpu_timers[0]);
	INIT_LIST_HEAD(&p->cpu_timers[1]);
	INIT_LIST_HEAD(&p->cpu_timers[2]);
Linus Torvalds's avatar
Linus Torvalds committed
995 996 997

	p->lock_depth = -1;		/* -1 = no lock */
	do_posix_clock_monotonic_gettime(&p->start_time);
998 999
	p->real_start_time = p->start_time;
	monotonic_to_bootbased(&p->real_start_time);
1000
#ifdef CONFIG_SECURITY
Linus Torvalds's avatar
Linus Torvalds committed
1001
	p->security = NULL;
1002
#endif
1003
	p->cap_bset = current->cap_bset;
Linus Torvalds's avatar
Linus Torvalds committed
1004 1005
	p->io_context = NULL;
	p->audit_context = NULL;
1006
	cgroup_fork(p);
Linus Torvalds's avatar
Linus Torvalds committed
1007
#ifdef CONFIG_NUMA
1008
	p->mempolicy = mpol_dup(p->mempolicy);
Linus Torvalds's avatar
Linus Torvalds committed
1009 1010 1011
 	if (IS_ERR(p->mempolicy)) {
 		retval = PTR_ERR(p->mempolicy);
 		p->mempolicy = NULL;
1012
 		goto bad_fork_cleanup_cgroup;
Linus Torvalds's avatar
Linus Torvalds committed
1013
 	}
1014
	mpol_fix_fork_child_flag(p);
Linus Torvalds's avatar
Linus Torvalds committed
1015
#endif
1016 1017
#ifdef CONFIG_TRACE_IRQFLAGS
	p->irq_events = 0;
1018 1019 1020
#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
	p->hardirqs_enabled = 1;
#else
1021
	p->hardirqs_enabled = 0;
1022
#endif
1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034
	p->hardirq_enable_ip = 0;
	p->hardirq_enable_event = 0;
	p->hardirq_disable_ip = _THIS_IP_;
	p->hardirq_disable_event = 0;
	p->softirqs_enabled = 1;
	p->softirq_enable_ip = _THIS_IP_;
	p->softirq_enable_event = 0;
	p->softirq_disable_ip = 0;
	p->softirq_disable_event = 0;
	p->hardirq_context = 0;
	p->softirq_context = 0;
#endif
Ingo Molnar's avatar
Ingo Molnar committed
1035 1036 1037 1038 1039
#ifdef CONFIG_LOCKDEP
	p->lockdep_depth = 0; /* no locks held yet */
	p->curr_chain_key = 0;
	p->lockdep_recursion = 0;
#endif
Linus Torvalds's avatar
Linus Torvalds committed
1040

1041 1042 1043 1044
#ifdef CONFIG_DEBUG_MUTEXES
	p->blocked_on = NULL; /* not blocked yet */
#endif

1045 1046 1047
	/* Perform scheduler related setup. Assign this task to a CPU. */
	sched_fork(p, clone_flags);

Linus Torvalds's avatar
Linus Torvalds committed
1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066
	if ((retval = security_task_alloc(p)))
		goto bad_fork_cleanup_policy;
	if ((retval = audit_alloc(p)))
		goto bad_fork_cleanup_security;
	/* copy all the process information */
	if ((retval = copy_semundo(clone_flags, p)))
		goto bad_fork_cleanup_audit;
	if ((retval = copy_files(clone_flags, p)))
		goto bad_fork_cleanup_semundo;
	if ((retval = copy_fs(clone_flags, p)))
		goto bad_fork_cleanup_files;
	if ((retval = copy_sighand(clone_flags, p)))
		goto bad_fork_cleanup_fs;
	if ((retval = copy_signal(clone_flags, p)))
		goto bad_fork_cleanup_sighand;
	if ((retval = copy_mm(clone_flags, p)))
		goto bad_fork_cleanup_signal;
	if ((retval = copy_keys(clone_flags, p)))
		goto bad_fork_cleanup_mm;
1067
	if ((retval = copy_namespaces(clone_flags, p)))
Linus Torvalds's avatar
Linus Torvalds committed
1068
		goto bad_fork_cleanup_keys;
1069
	if ((retval = copy_io(clone_flags, p)))
1070
		goto bad_fork_cleanup_namespaces;
Linus Torvalds's avatar
Linus Torvalds committed
1071 1072
	retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
	if (retval)
1073
		goto bad_fork_cleanup_io;
Linus Torvalds's avatar
Linus Torvalds committed
1074

1075 1076 1077 1078
	if (pid != &init_struct_pid) {
		retval = -ENOMEM;
		pid = alloc_pid(task_active_pid_ns(p));
		if (!pid)
1079
			goto bad_fork_cleanup_io;
1080 1081 1082 1083 1084 1085

		if (clone_flags & CLONE_NEWPID) {
			retval = pid_ns_prepare_proc(task_active_pid_ns(p));
			if (retval < 0)
				goto bad_fork_free_pid;
		}
1086 1087 1088 1089 1090 1091 1092
	}

	p->pid = pid_nr(pid);
	p->tgid = p->pid;
	if (clone_flags & CLONE_THREAD)
		p->tgid = current->tgid;

Linus Torvalds's avatar
Linus Torvalds committed
1093 1094 1095 1096 1097
	p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
	/*
	 * Clear TID on mm_release()?
	 */
	p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL;
1098
#ifdef CONFIG_FUTEX
1099 1100 1101 1102
	p->robust_list = NULL;
#ifdef CONFIG_COMPAT
	p->compat_robust_list = NULL;
#endif
1103 1104
	INIT_LIST_HEAD(&p->pi_state_list);
	p->pi_state_cache = NULL;
1105
#endif
1106 1107 1108 1109 1110 1111
	/*
	 * sigaltstack should be cleared when sharing the same VM
	 */
	if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
		p->sas_ss_sp = p->sas_ss_size = 0;

Linus Torvalds's avatar
Linus Torvalds committed
1112 1113 1114 1115 1116
	/*
	 * Syscall tracing should be turned off in the child regardless
	 * of CLONE_PTRACE.
	 */
	clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
1117 1118 1119
#ifdef TIF_SYSCALL_EMU
	clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
#endif
Arjan van de Ven's avatar
Arjan van de Ven committed
1120
	clear_all_latency_tracing(p);
Linus Torvalds's avatar
Linus Torvalds committed
1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135

	/* Our parent execution domain becomes current domain
	   These must match for thread signalling to apply */
	p->parent_exec_id = p->self_exec_id;

	/* ok, now we should be set up.. */
	p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
	p->pdeath_signal = 0;
	p->exit_state = 0;

	/*
	 * Ok, make it visible to the rest of the system.
	 * We dont wake it up yet.
	 */
	p->group_leader = p;
1136
	INIT_LIST_HEAD(&p->thread_group);
Roland McGrath's avatar
Roland McGrath committed
1137 1138
	INIT_LIST_HEAD(&p->ptrace_entry);
	INIT_LIST_HEAD(&p->ptraced);
Linus Torvalds's avatar
Linus Torvalds committed
1139

1140 1141 1142 1143 1144 1145
	/* Now that the task is set up, run cgroup callbacks if
	 * necessary. We need to run them before the task is visible
	 * on the tasklist. */
	cgroup_fork_callbacks(p);
	cgroup_callbacks_done = 1;

Linus Torvalds's avatar
Linus Torvalds committed
1146 1147 1148 1149
	/* Need tasklist lock for parent etc handling! */
	write_lock_irq(&tasklist_lock);

	/*
1150 1151 1152 1153 1154 1155 1156
	 * The task hasn't been attached yet, so its cpus_allowed mask will
	 * not be changed, nor will its assigned CPU.
	 *
	 * The cpus_allowed mask of the parent may have changed after it was
	 * copied first time - so re-copy it here, then check the child's CPU
	 * to ensure it is on a valid CPU (and if not, just force it back to
	 * parent's CPU). This avoids alot of nasty races.
Linus Torvalds's avatar
Linus Torvalds committed
1157 1158
	 */
	p->cpus_allowed = current->cpus_allowed;
Peter Zijlstra's avatar
Peter Zijlstra committed
1159
	p->rt.nr_cpus_allowed = current->rt.nr_cpus_allowed;
1160 1161
	if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed) ||
			!cpu_online(task_cpu(p))))
1162
		set_task_cpu(p, smp_processor_id());
Linus Torvalds's avatar
Linus Torvalds committed
1163 1164 1165 1166 1167 1168 1169 1170

	/* CLONE_PARENT re-uses the old parent */
	if (clone_flags & (CLONE_PARENT|CLONE_THREAD))
		p->real_parent = current->real_parent;
	else
		p->real_parent = current;
	p->parent = p->real_parent;

1171
	spin_lock(&current->sighand->siglock);
1172 1173 1174 1175 1176 1177 1178 1179 1180

	/*
	 * Process group and session signals need to be delivered to just the
	 * parent before the fork or both the parent and the child after the
	 * fork. Restart if a signal comes in before we add the new process to
	 * it's process group.
	 * A fatal signal pending means that current will exit, so the new
	 * thread can't slip out of an OOM kill (or normal SIGKILL).
 	 */
Daniel Walker's avatar
Daniel Walker committed
1181
	recalc_sigpending();
1182 1183 1184 1185
	if (signal_pending(current)) {
		spin_unlock(&current->sighand->siglock);
		write_unlock_irq(&tasklist_lock);
		retval = -ERESTARTNOINTR;
1186
		goto bad_fork_free_pid;
1187 1188
	}

Linus Torvalds's avatar
Linus Torvalds committed
1189 1190
	if (clone_flags & CLONE_THREAD) {
		p->group_leader = current->group_leader;
1191
		list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group);
Linus Torvalds's avatar
Linus Torvalds committed
1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208

		if (!cputime_eq(current->signal->it_virt_expires,
				cputime_zero) ||
		    !cputime_eq(current->signal->it_prof_expires,
				cputime_zero) ||
		    current->signal->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY ||
		    !list_empty(&current->signal->cpu_timers[0]) ||
		    !list_empty(&current->signal->cpu_timers[1]) ||
		    !list_empty(&current->signal->cpu_timers[2])) {
			/*
			 * Have child wake up on its first tick to check
			 * for process CPU timers.
			 */
			p->it_prof_expires = jiffies_to_cputime(1);
		}
	}

1209
	if (likely(p->pid)) {
Roland McGrath's avatar
Roland McGrath committed
1210
		list_add_tail(&p->sibling, &p->real_parent->children);
1211 1212 1213 1214
		if (unlikely(p->ptrace & PT_PTRACED))
			__ptrace_link(p, current->parent);

		if (thread_group_leader(p)) {
Eric W. Biederman's avatar
Eric W. Biederman committed
1215
			if (clone_flags & CLONE_NEWPID)
1216
				p->nsproxy->pid_ns->child_reaper = p;
1217

1218
			p->signal->leader_pid = pid;
Eric W. Biederman's avatar
Eric W. Biederman committed
1219 1220 1221 1222 1223
			p->signal->tty = current->signal->tty;
			set_task_pgrp(p, task_pgrp_nr(current));
			set_task_session(p, task_session_nr(current));
			attach_pid(p, PIDTYPE_PGID, task_pgrp(current));
			attach_pid(p, PIDTYPE_SID, task_session(current));
1224
			list_add_tail_rcu(&p->tasks, &init_task.tasks);
Linus Torvalds's avatar
Linus Torvalds committed
1225
			__get_cpu_var(process_counts)++;
1226
		}
1227
		attach_pid(p, PIDTYPE_PID, pid);
1228
		nr_threads++;
Linus Torvalds's avatar
Linus Torvalds committed
1229 1230 1231
	}

	total_forks++;
1232
	spin_unlock(&current->sighand->siglock);
Linus Torvalds's avatar
Linus Torvalds committed
1233
	write_unlock_irq(&tasklist_lock);
1234
	proc_fork_connector(p);
1235
	cgroup_post_fork(p);
Linus Torvalds's avatar
Linus Torvalds committed
1236 1237
	return p;

1238 1239 1240
bad_fork_free_pid:
	if (pid != &init_struct_pid)
		free_pid(pid);
1241 1242
bad_fork_cleanup_io:
	put_io_context(p->io_context);
1243
bad_fork_cleanup_namespaces:
1244
	exit_task_namespaces(p);
Linus Torvalds's avatar
Linus Torvalds committed
1245 1246 1247 1248 1249 1250
bad_fork_cleanup_keys:
	exit_keys(p);
bad_fork_cleanup_mm:
	if (p->mm)
		mmput(p->mm);
bad_fork_cleanup_signal:
1251
	cleanup_signal(p);
Linus Torvalds's avatar
Linus Torvalds committed
1252
bad_fork_cleanup_sighand:
1253
	__cleanup_sighand(p->sighand);
Linus Torvalds's avatar
Linus Torvalds committed
1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265
bad_fork_cleanup_fs:
	exit_fs(p); /* blocking */
bad_fork_cleanup_files:
	exit_files(p); /* blocking */
bad_fork_cleanup_semundo:
	exit_sem(p);
bad_fork_cleanup_audit:
	audit_free(p);
bad_fork_cleanup_security:
	security_task_free(p);
bad_fork_cleanup_policy:
#ifdef CONFIG_NUMA
1266
	mpol_put(p->mempolicy);
1267
bad_fork_cleanup_cgroup:
Linus Torvalds's avatar
Linus Torvalds committed
1268
#endif
1269
	cgroup_exit(p, cgroup_callbacks_done);
1270
	delayacct_tsk_free(p);
Linus Torvalds's avatar
Linus Torvalds committed
1271 1272 1273
	if (p->binfmt)
		module_put(p->binfmt->module);
bad_fork_cleanup_put_domain:
1274
	module_put(task_thread_info(p)->exec_domain->module);
Linus Torvalds's avatar
Linus Torvalds committed
1275 1276 1277 1278 1279 1280
bad_fork_cleanup_count:
	put_group_info(p->group_info);
	atomic_dec(&p->user->processes);
	free_uid(p->user);
bad_fork_free:
	free_task(p);
1281 1282
fork_out:
	return ERR_PTR(retval);
Linus Torvalds's avatar
Linus Torvalds committed
1283 1284
}

Adrian Bunk's avatar
Adrian Bunk committed
1285
noinline struct pt_regs * __cpuinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
Linus Torvalds's avatar
Linus Torvalds committed
1286 1287 1288 1289 1290
{
	memset(regs, 0, sizeof(struct pt_regs));
	return regs;
}

1291
struct task_struct * __cpuinit fork_idle(int cpu)
Linus Torvalds's avatar
Linus Torvalds committed
1292
{
1293
	struct task_struct *task;
Linus Torvalds's avatar
Linus Torvalds committed
1294 1295
	struct pt_regs regs;

1296
	task = copy_process(CLONE_VM, 0, idle_regs(&regs), 0, NULL,
1297
				&init_struct_pid);
1298 1299
	if (!IS_ERR(task))
		init_idle(task, cpu);
1300

Linus Torvalds's avatar
Linus Torvalds committed
1301 1302 1303
	return task;
}

Alexey Dobriyan's avatar
Alexey Dobriyan committed
1304
static int fork_traceflag(unsigned clone_flags)
Linus Torvalds's avatar
Linus Torvalds committed
1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334
{
	if (clone_flags & CLONE_UNTRACED)
		return 0;
	else if (clone_flags & CLONE_VFORK) {
		if (current->ptrace & PT_TRACE_VFORK)
			return PTRACE_EVENT_VFORK;
	} else if ((clone_flags & CSIGNAL) != SIGCHLD) {
		if (current->ptrace & PT_TRACE_CLONE)
			return PTRACE_EVENT_CLONE;
	} else if (current->ptrace & PT_TRACE_FORK)
		return PTRACE_EVENT_FORK;

	return 0;
}

/*
 *  Ok, this is the main fork-routine.
 *
 * It copies the process, and if successful kick-starts
 * it and waits for it to finish using the VM if required.
 */
long do_fork(unsigned long clone_flags,
	      unsigned long stack_start,
	      struct pt_regs *regs,
	      unsigned long stack_size,
	      int __user *parent_tidptr,
	      int __user *child_tidptr)
{
	struct task_struct *p;
	int trace = 0;
1335
	long nr;
Linus Torvalds's avatar
Linus Torvalds committed
1336

1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353
	/*
	 * We hope to recycle these flags after 2.6.26
	 */
	if (unlikely(clone_flags & CLONE_STOPPED)) {
		static int __read_mostly count = 100;

		if (count > 0 && printk_ratelimit()) {
			char comm[TASK_COMM_LEN];

			count--;
			printk(KERN_INFO "fork(): process `%s' used deprecated "
					"clone flags 0x%lx\n",
				get_task_comm(comm, current),
				clone_flags & CLONE_STOPPED);
		}
	}

Linus Torvalds's avatar
Linus Torvalds committed
1354 1355 1356 1357 1358 1359
	if (unlikely(current->ptrace)) {
		trace = fork_traceflag (clone_flags);
		if (trace)
			clone_flags |= CLONE_PTRACE;
	}

1360
	p = copy_process(clone_flags, stack_start, regs, stack_size,
1361
			child_tidptr, NULL);
Linus Torvalds's avatar
Linus Torvalds committed
1362 1363 1364 1365 1366 1367 1368
	/*
	 * Do this prior waking up the new thread - the thread pointer
	 * might get invalid after that point, if the thread exits quickly.
	 */
	if (!IS_ERR(p)) {
		struct completion vfork;

1369
		nr = task_pid_vnr(p);
1370 1371 1372

		if (clone_flags & CLONE_PARENT_SETTID)
			put_user(nr, parent_tidptr);
1373

Linus Torvalds's avatar
Linus Torvalds committed
1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389
		if (clone_flags & CLONE_VFORK) {
			p->vfork_done = &vfork;
			init_completion(&vfork);
		}

		if ((p->ptrace & PT_PTRACED) || (clone_flags & CLONE_STOPPED)) {
			/*
			 * We'll start up with an immediate SIGSTOP.
			 */
			sigaddset(&p->pending.signal, SIGSTOP);
			set_tsk_thread_flag(p, TIF_SIGPENDING);
		}

		if (!(clone_flags & CLONE_STOPPED))
			wake_up_new_task(p, clone_flags);
		else
1390
			__set_task_state(p, TASK_STOPPED);
Linus Torvalds's avatar
Linus Torvalds committed
1391 1392

		if (unlikely (trace)) {
1393
			current->ptrace_message = nr;
Linus Torvalds's avatar
Linus Torvalds committed
1394 1395 1396 1397
			ptrace_notify ((trace << 8) | SIGTRAP);
		}

		if (clone_flags & CLONE_VFORK) {
1398
			freezer_do_not_count();
Linus Torvalds's avatar
Linus Torvalds committed
1399
			wait_for_completion(&vfork);
1400
			freezer_count();
1401 1402
			if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE)) {
				current->ptrace_message = nr;
Linus Torvalds's avatar
Linus Torvalds committed
1403
				ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP);
1404
			}
Linus Torvalds's avatar
Linus Torvalds committed
1405 1406
		}
	} else {
1407
		nr = PTR_ERR(p);
Linus Torvalds's avatar
Linus Torvalds committed
1408
	}
1409
	return nr;
Linus Torvalds's avatar
Linus Torvalds committed
1410 1411
}

1412 1413 1414 1415
#ifndef ARCH_MIN_MMSTRUCT_ALIGN
#define ARCH_MIN_MMSTRUCT_ALIGN 0
#endif

1416
static void sighand_ctor(struct kmem_cache *cachep, void *data)
1417 1418 1419
{
	struct sighand_struct *sighand = data;

1420
	spin_lock_init(&sighand->siglock);
Davide Libenzi's avatar
Davide Libenzi committed
1421
	init_waitqueue_head(&sighand->signalfd_wqh);
1422 1423
}

Linus Torvalds's avatar
Linus Torvalds committed
1424 1425 1426 1427
void __init proc_caches_init(void)
{
	sighand_cachep = kmem_cache_create("sighand_cache",
			sizeof(struct sighand_struct), 0,
1428
			SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU,
1429
			sighand_ctor);
Linus Torvalds's avatar
Linus Torvalds committed
1430 1431
	signal_cachep = kmem_cache_create("signal_cache",
			sizeof(struct signal_struct), 0,
1432 1433
			SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
	files_cachep = kmem_cache_create("files_cache",
Linus Torvalds's avatar
Linus Torvalds committed
1434
			sizeof(struct files_struct), 0,
1435 1436
			SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
	fs_cachep = kmem_cache_create("fs_cache",
Linus Torvalds's avatar
Linus Torvalds committed
1437
			sizeof(struct fs_struct), 0,
1438
			SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
Linus Torvalds's avatar
Linus Torvalds committed
1439 1440
	vm_area_cachep = kmem_cache_create("vm_area_struct",
			sizeof(struct vm_area_struct), 0,
1441
			SLAB_PANIC, NULL);
Linus Torvalds's avatar
Linus Torvalds committed
1442
	mm_cachep = kmem_cache_create("mm_struct",
1443
			sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
1444
			SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
Linus Torvalds's avatar
Linus Torvalds committed
1445
}
1446 1447 1448 1449 1450

/*
 * Check constraints on flags passed to the unshare system call and
 * force unsharing of additional process context as appropriate.
 */
Alexey Dobriyan's avatar
Alexey Dobriyan committed
1451
static void check_unshare_flags(unsigned long *flags_ptr)
1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492
{
	/*
	 * If unsharing a thread from a thread group, must also
	 * unshare vm.
	 */
	if (*flags_ptr & CLONE_THREAD)
		*flags_ptr |= CLONE_VM;

	/*
	 * If unsharing vm, must also unshare signal handlers.
	 */
	if (*flags_ptr & CLONE_VM)
		*flags_ptr |= CLONE_SIGHAND;

	/*
	 * If unsharing signal handlers and the task was created
	 * using CLONE_THREAD, then must unshare the thread
	 */
	if ((*flags_ptr & CLONE_SIGHAND) &&
	    (atomic_read(&current->signal->count) > 1))
		*flags_ptr |= CLONE_THREAD;

	/*
	 * If unsharing namespace, must also unshare filesystem information.
	 */
	if (*flags_ptr & CLONE_NEWNS)
		*flags_ptr |= CLONE_FS;
}

/*
 * Unsharing of tasks created with CLONE_THREAD is not supported yet
 */
static int unshare_thread(unsigned long unshare_flags)
{
	if (unshare_flags & CLONE_THREAD)
		return -EINVAL;

	return 0;
}

/*
1493
 * Unshare the filesystem structure if it is being shared
1494 1495 1496 1497 1498 1499
 */
static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
{
	struct fs_struct *fs = current->fs;

	if ((unshare_flags & CLONE_FS) &&
1500 1501 1502 1503 1504
	    (fs && atomic_read(&fs->count) > 1)) {
		*new_fsp = __copy_fs_struct(current->fs);
		if (!*new_fsp)
			return -ENOMEM;
	}
1505 1506 1507 1508 1509

	return 0;
}

/*
1510
 * Unsharing of sighand is not supported yet
1511 1512 1513 1514 1515
 */
static int unshare_sighand(unsigned long