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/slab.h> 15 #include <linux/init.h> 16 #include <linux/unistd.h> 17 #include <linux/module.h> 18 #include <linux/vmalloc.h> 19 #include <linux/completion.h> 20 #include <linux/personality.h> 21 #include <linux/mempolicy.h> 22 #include <linux/sem.h> 23 #include <linux/file.h> 24 #include <linux/fdtable.h> 25 #include <linux/iocontext.h> 26 #include <linux/key.h> 27 #include <linux/binfmts.h> 28 #include <linux/mman.h> 29 #include <linux/mmu_notifier.h> 30 #include <linux/fs.h> 31 #include <linux/nsproxy.h> 32 #include <linux/capability.h> 33 #include <linux/cpu.h> 34 #include <linux/cgroup.h> 35 #include <linux/security.h> 36 #include <linux/hugetlb.h> 37 #include <linux/swap.h> 38 #include <linux/syscalls.h> 39 #include <linux/jiffies.h> 40 #include <linux/tracehook.h> 41 #include <linux/futex.h> 42 #include <linux/compat.h> 43 #include <linux/kthread.h> 44 #include <linux/task_io_accounting_ops.h> 45 #include <linux/rcupdate.h> 46 #include <linux/ptrace.h> 47 #include <linux/mount.h> 48 #include <linux/audit.h> 49 #include <linux/memcontrol.h> 50 #include <linux/ftrace.h> 51 #include <linux/profile.h> 52 #include <linux/rmap.h> 53 #include <linux/ksm.h> 54 #include <linux/acct.h> 55 #include <linux/tsacct_kern.h> 56 #include <linux/cn_proc.h> 57 #include <linux/freezer.h> 58 #include <linux/delayacct.h> 59 #include <linux/taskstats_kern.h> 60 #include <linux/random.h> 61 #include <linux/tty.h> 62 #include <linux/proc_fs.h> 63 #include <linux/blkdev.h> 64 #include <linux/fs_struct.h> 65 #include <linux/magic.h> 66 #include <linux/perf_event.h> 67 #include <linux/posix-timers.h> 68 #include <linux/user-return-notifier.h> 69 #include <linux/oom.h> 70 #include <linux/khugepaged.h> 71 72 #include <asm/pgtable.h> 73 #include <asm/pgalloc.h> 74 #include <asm/uaccess.h> 75 #include <asm/mmu_context.h> 76 #include <asm/cacheflush.h> 77 #include <asm/tlbflush.h> 78 79 #include <trace/events/sched.h> 80 81 /* 82 * Protected counters by write_lock_irq(&tasklist_lock) 83 */ 84 unsigned long total_forks; /* Handle normal Linux uptimes. */ 85 int nr_threads; /* The idle threads do not count.. */ 86 87 int max_threads; /* tunable limit on nr_threads */ 88 89 DEFINE_PER_CPU(unsigned long, process_counts) = 0; 90 91 __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */ 92 93 #ifdef CONFIG_PROVE_RCU 94 int lockdep_tasklist_lock_is_held(void) 95 { 96 return lockdep_is_held(&tasklist_lock); 97 } 98 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held); 99 #endif /* #ifdef CONFIG_PROVE_RCU */ 100 101 int nr_processes(void) 102 { 103 int cpu; 104 int total = 0; 105 106 for_each_possible_cpu(cpu) 107 total += per_cpu(process_counts, cpu); 108 109 return total; 110 } 111 112 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR 113 # define alloc_task_struct_node(node) \ 114 kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node) 115 # define free_task_struct(tsk) \ 116 kmem_cache_free(task_struct_cachep, (tsk)) 117 static struct kmem_cache *task_struct_cachep; 118 #endif 119 120 #ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR 121 static struct thread_info *alloc_thread_info_node(struct task_struct *tsk, 122 int node) 123 { 124 #ifdef CONFIG_DEBUG_STACK_USAGE 125 gfp_t mask = GFP_KERNEL | __GFP_ZERO; 126 #else 127 gfp_t mask = GFP_KERNEL; 128 #endif 129 struct page *page = alloc_pages_node(node, mask, THREAD_SIZE_ORDER); 130 131 return page ? page_address(page) : NULL; 132 } 133 134 static inline void free_thread_info(struct thread_info *ti) 135 { 136 free_pages((unsigned long)ti, THREAD_SIZE_ORDER); 137 } 138 #endif 139 140 /* SLAB cache for signal_struct structures (tsk->signal) */ 141 static struct kmem_cache *signal_cachep; 142 143 /* SLAB cache for sighand_struct structures (tsk->sighand) */ 144 struct kmem_cache *sighand_cachep; 145 146 /* SLAB cache for files_struct structures (tsk->files) */ 147 struct kmem_cache *files_cachep; 148 149 /* SLAB cache for fs_struct structures (tsk->fs) */ 150 struct kmem_cache *fs_cachep; 151 152 /* SLAB cache for vm_area_struct structures */ 153 struct kmem_cache *vm_area_cachep; 154 155 /* SLAB cache for mm_struct structures (tsk->mm) */ 156 static struct kmem_cache *mm_cachep; 157 158 static void account_kernel_stack(struct thread_info *ti, int account) 159 { 160 struct zone *zone = page_zone(virt_to_page(ti)); 161 162 mod_zone_page_state(zone, NR_KERNEL_STACK, account); 163 } 164 165 void free_task(struct task_struct *tsk) 166 { 167 prop_local_destroy_single(&tsk->dirties); 168 account_kernel_stack(tsk->stack, -1); 169 free_thread_info(tsk->stack); 170 rt_mutex_debug_task_free(tsk); 171 ftrace_graph_exit_task(tsk); 172 free_task_struct(tsk); 173 } 174 EXPORT_SYMBOL(free_task); 175 176 static inline void free_signal_struct(struct signal_struct *sig) 177 { 178 taskstats_tgid_free(sig); 179 sched_autogroup_exit(sig); 180 kmem_cache_free(signal_cachep, sig); 181 } 182 183 static inline void put_signal_struct(struct signal_struct *sig) 184 { 185 if (atomic_dec_and_test(&sig->sigcnt)) 186 free_signal_struct(sig); 187 } 188 189 void __put_task_struct(struct task_struct *tsk) 190 { 191 WARN_ON(!tsk->exit_state); 192 WARN_ON(atomic_read(&tsk->usage)); 193 WARN_ON(tsk == current); 194 195 exit_creds(tsk); 196 delayacct_tsk_free(tsk); 197 put_signal_struct(tsk->signal); 198 199 if (!profile_handoff_task(tsk)) 200 free_task(tsk); 201 } 202 EXPORT_SYMBOL_GPL(__put_task_struct); 203 204 /* 205 * macro override instead of weak attribute alias, to workaround 206 * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions. 207 */ 208 #ifndef arch_task_cache_init 209 #define arch_task_cache_init() 210 #endif 211 212 void __init fork_init(unsigned long mempages) 213 { 214 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR 215 #ifndef ARCH_MIN_TASKALIGN 216 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES 217 #endif 218 /* create a slab on which task_structs can be allocated */ 219 task_struct_cachep = 220 kmem_cache_create("task_struct", sizeof(struct task_struct), 221 ARCH_MIN_TASKALIGN, SLAB_PANIC | SLAB_NOTRACK, NULL); 222 #endif 223 224 /* do the arch specific task caches init */ 225 arch_task_cache_init(); 226 227 /* 228 * The default maximum number of threads is set to a safe 229 * value: the thread structures can take up at most half 230 * of memory. 231 */ 232 max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE); 233 234 /* 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.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2; 241 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2; 242 init_task.signal->rlim[RLIMIT_SIGPENDING] = 243 init_task.signal->rlim[RLIMIT_NPROC]; 244 } 245 246 int __attribute__((weak)) arch_dup_task_struct(struct task_struct *dst, 247 struct task_struct *src) 248 { 249 *dst = *src; 250 return 0; 251 } 252 253 static struct task_struct *dup_task_struct(struct task_struct *orig) 254 { 255 struct task_struct *tsk; 256 struct thread_info *ti; 257 unsigned long *stackend; 258 int node = tsk_fork_get_node(orig); 259 int err; 260 261 prepare_to_copy(orig); 262 263 tsk = alloc_task_struct_node(node); 264 if (!tsk) 265 return NULL; 266 267 ti = alloc_thread_info_node(tsk, node); 268 if (!ti) { 269 free_task_struct(tsk); 270 return NULL; 271 } 272 273 err = arch_dup_task_struct(tsk, orig); 274 if (err) 275 goto out; 276 277 tsk->stack = ti; 278 279 err = prop_local_init_single(&tsk->dirties); 280 if (err) 281 goto out; 282 283 setup_thread_stack(tsk, orig); 284 clear_user_return_notifier(tsk); 285 clear_tsk_need_resched(tsk); 286 stackend = end_of_stack(tsk); 287 *stackend = STACK_END_MAGIC; /* for overflow detection */ 288 289 #ifdef CONFIG_CC_STACKPROTECTOR 290 tsk->stack_canary = get_random_int(); 291 #endif 292 293 /* One for us, one for whoever does the "release_task()" (usually parent) */ 294 atomic_set(&tsk->usage,2); 295 atomic_set(&tsk->fs_excl, 0); 296 #ifdef CONFIG_BLK_DEV_IO_TRACE 297 tsk->btrace_seq = 0; 298 #endif 299 tsk->splice_pipe = NULL; 300 301 account_kernel_stack(ti, 1); 302 303 return tsk; 304 305 out: 306 free_thread_info(ti); 307 free_task_struct(tsk); 308 return NULL; 309 } 310 311 #ifdef CONFIG_MMU 312 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) 313 { 314 struct vm_area_struct *mpnt, *tmp, *prev, **pprev; 315 struct rb_node **rb_link, *rb_parent; 316 int retval; 317 unsigned long charge; 318 struct mempolicy *pol; 319 320 down_write(&oldmm->mmap_sem); 321 flush_cache_dup_mm(oldmm); 322 /* 323 * Not linked in yet - no deadlock potential: 324 */ 325 down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING); 326 327 mm->locked_vm = 0; 328 mm->mmap = NULL; 329 mm->mmap_cache = NULL; 330 mm->free_area_cache = oldmm->mmap_base; 331 mm->cached_hole_size = ~0UL; 332 mm->map_count = 0; 333 cpumask_clear(mm_cpumask(mm)); 334 mm->mm_rb = RB_ROOT; 335 rb_link = &mm->mm_rb.rb_node; 336 rb_parent = NULL; 337 pprev = &mm->mmap; 338 retval = ksm_fork(mm, oldmm); 339 if (retval) 340 goto out; 341 retval = khugepaged_fork(mm, oldmm); 342 if (retval) 343 goto out; 344 345 prev = NULL; 346 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) { 347 struct file *file; 348 349 if (mpnt->vm_flags & VM_DONTCOPY) { 350 long pages = vma_pages(mpnt); 351 mm->total_vm -= pages; 352 vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file, 353 -pages); 354 continue; 355 } 356 charge = 0; 357 if (mpnt->vm_flags & VM_ACCOUNT) { 358 unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT; 359 if (security_vm_enough_memory(len)) 360 goto fail_nomem; 361 charge = len; 362 } 363 tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 364 if (!tmp) 365 goto fail_nomem; 366 *tmp = *mpnt; 367 INIT_LIST_HEAD(&tmp->anon_vma_chain); 368 pol = mpol_dup(vma_policy(mpnt)); 369 retval = PTR_ERR(pol); 370 if (IS_ERR(pol)) 371 goto fail_nomem_policy; 372 vma_set_policy(tmp, pol); 373 tmp->vm_mm = mm; 374 if (anon_vma_fork(tmp, mpnt)) 375 goto fail_nomem_anon_vma_fork; 376 tmp->vm_flags &= ~VM_LOCKED; 377 tmp->vm_next = tmp->vm_prev = NULL; 378 file = tmp->vm_file; 379 if (file) { 380 struct inode *inode = file->f_path.dentry->d_inode; 381 struct address_space *mapping = file->f_mapping; 382 383 get_file(file); 384 if (tmp->vm_flags & VM_DENYWRITE) 385 atomic_dec(&inode->i_writecount); 386 mutex_lock(&mapping->i_mmap_mutex); 387 if (tmp->vm_flags & VM_SHARED) 388 mapping->i_mmap_writable++; 389 flush_dcache_mmap_lock(mapping); 390 /* insert tmp into the share list, just after mpnt */ 391 vma_prio_tree_add(tmp, mpnt); 392 flush_dcache_mmap_unlock(mapping); 393 mutex_unlock(&mapping->i_mmap_mutex); 394 } 395 396 /* 397 * Clear hugetlb-related page reserves for children. This only 398 * affects MAP_PRIVATE mappings. Faults generated by the child 399 * are not guaranteed to succeed, even if read-only 400 */ 401 if (is_vm_hugetlb_page(tmp)) 402 reset_vma_resv_huge_pages(tmp); 403 404 /* 405 * Link in the new vma and copy the page table entries. 406 */ 407 *pprev = tmp; 408 pprev = &tmp->vm_next; 409 tmp->vm_prev = prev; 410 prev = tmp; 411 412 __vma_link_rb(mm, tmp, rb_link, rb_parent); 413 rb_link = &tmp->vm_rb.rb_right; 414 rb_parent = &tmp->vm_rb; 415 416 mm->map_count++; 417 retval = copy_page_range(mm, oldmm, mpnt); 418 419 if (tmp->vm_ops && tmp->vm_ops->open) 420 tmp->vm_ops->open(tmp); 421 422 if (retval) 423 goto out; 424 } 425 /* a new mm has just been created */ 426 arch_dup_mmap(oldmm, mm); 427 retval = 0; 428 out: 429 up_write(&mm->mmap_sem); 430 flush_tlb_mm(oldmm); 431 up_write(&oldmm->mmap_sem); 432 return retval; 433 fail_nomem_anon_vma_fork: 434 mpol_put(pol); 435 fail_nomem_policy: 436 kmem_cache_free(vm_area_cachep, tmp); 437 fail_nomem: 438 retval = -ENOMEM; 439 vm_unacct_memory(charge); 440 goto out; 441 } 442 443 static inline int mm_alloc_pgd(struct mm_struct * mm) 444 { 445 mm->pgd = pgd_alloc(mm); 446 if (unlikely(!mm->pgd)) 447 return -ENOMEM; 448 return 0; 449 } 450 451 static inline void mm_free_pgd(struct mm_struct * mm) 452 { 453 pgd_free(mm, mm->pgd); 454 } 455 #else 456 #define dup_mmap(mm, oldmm) (0) 457 #define mm_alloc_pgd(mm) (0) 458 #define mm_free_pgd(mm) 459 #endif /* CONFIG_MMU */ 460 461 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock); 462 463 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL)) 464 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm))) 465 466 static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT; 467 468 static int __init coredump_filter_setup(char *s) 469 { 470 default_dump_filter = 471 (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) & 472 MMF_DUMP_FILTER_MASK; 473 return 1; 474 } 475 476 __setup("coredump_filter=", coredump_filter_setup); 477 478 #include <linux/init_task.h> 479 480 static void mm_init_aio(struct mm_struct *mm) 481 { 482 #ifdef CONFIG_AIO 483 spin_lock_init(&mm->ioctx_lock); 484 INIT_HLIST_HEAD(&mm->ioctx_list); 485 #endif 486 } 487 488 int mm_init_cpumask(struct mm_struct *mm, struct mm_struct *oldmm) 489 { 490 #ifdef CONFIG_CPUMASK_OFFSTACK 491 if (!alloc_cpumask_var(&mm->cpu_vm_mask_var, GFP_KERNEL)) 492 return -ENOMEM; 493 494 if (oldmm) 495 cpumask_copy(mm_cpumask(mm), mm_cpumask(oldmm)); 496 else 497 memset(mm_cpumask(mm), 0, cpumask_size()); 498 #endif 499 return 0; 500 } 501 502 static struct mm_struct * mm_init(struct mm_struct * mm, struct task_struct *p) 503 { 504 atomic_set(&mm->mm_users, 1); 505 atomic_set(&mm->mm_count, 1); 506 init_rwsem(&mm->mmap_sem); 507 INIT_LIST_HEAD(&mm->mmlist); 508 mm->flags = (current->mm) ? 509 (current->mm->flags & MMF_INIT_MASK) : default_dump_filter; 510 mm->core_state = NULL; 511 mm->nr_ptes = 0; 512 memset(&mm->rss_stat, 0, sizeof(mm->rss_stat)); 513 spin_lock_init(&mm->page_table_lock); 514 mm->free_area_cache = TASK_UNMAPPED_BASE; 515 mm->cached_hole_size = ~0UL; 516 mm_init_aio(mm); 517 mm_init_owner(mm, p); 518 atomic_set(&mm->oom_disable_count, 0); 519 520 if (likely(!mm_alloc_pgd(mm))) { 521 mm->def_flags = 0; 522 mmu_notifier_mm_init(mm); 523 return mm; 524 } 525 526 free_mm(mm); 527 return NULL; 528 } 529 530 /* 531 * Allocate and initialize an mm_struct. 532 */ 533 struct mm_struct * mm_alloc(void) 534 { 535 struct mm_struct * mm; 536 537 mm = allocate_mm(); 538 if (!mm) 539 return NULL; 540 541 memset(mm, 0, sizeof(*mm)); 542 mm = mm_init(mm, current); 543 if (!mm) 544 return NULL; 545 546 if (mm_init_cpumask(mm, NULL)) { 547 mm_free_pgd(mm); 548 free_mm(mm); 549 return NULL; 550 } 551 552 return mm; 553 } 554 555 /* 556 * Called when the last reference to the mm 557 * is dropped: either by a lazy thread or by 558 * mmput. Free the page directory and the mm. 559 */ 560 void __mmdrop(struct mm_struct *mm) 561 { 562 BUG_ON(mm == &init_mm); 563 free_cpumask_var(mm->cpu_vm_mask_var); 564 mm_free_pgd(mm); 565 destroy_context(mm); 566 mmu_notifier_mm_destroy(mm); 567 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 568 VM_BUG_ON(mm->pmd_huge_pte); 569 #endif 570 free_mm(mm); 571 } 572 EXPORT_SYMBOL_GPL(__mmdrop); 573 574 /* 575 * Decrement the use count and release all resources for an mm. 576 */ 577 void mmput(struct mm_struct *mm) 578 { 579 might_sleep(); 580 581 if (atomic_dec_and_test(&mm->mm_users)) { 582 exit_aio(mm); 583 ksm_exit(mm); 584 khugepaged_exit(mm); /* must run before exit_mmap */ 585 exit_mmap(mm); 586 set_mm_exe_file(mm, NULL); 587 if (!list_empty(&mm->mmlist)) { 588 spin_lock(&mmlist_lock); 589 list_del(&mm->mmlist); 590 spin_unlock(&mmlist_lock); 591 } 592 put_swap_token(mm); 593 if (mm->binfmt) 594 module_put(mm->binfmt->module); 595 mmdrop(mm); 596 } 597 } 598 EXPORT_SYMBOL_GPL(mmput); 599 600 /** 601 * get_task_mm - acquire a reference to the task's mm 602 * 603 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning 604 * this kernel workthread has transiently adopted a user mm with use_mm, 605 * to do its AIO) is not set and if so returns a reference to it, after 606 * bumping up the use count. User must release the mm via mmput() 607 * after use. Typically used by /proc and ptrace. 608 */ 609 struct mm_struct *get_task_mm(struct task_struct *task) 610 { 611 struct mm_struct *mm; 612 613 task_lock(task); 614 mm = task->mm; 615 if (mm) { 616 if (task->flags & PF_KTHREAD) 617 mm = NULL; 618 else 619 atomic_inc(&mm->mm_users); 620 } 621 task_unlock(task); 622 return mm; 623 } 624 EXPORT_SYMBOL_GPL(get_task_mm); 625 626 /* Please note the differences between mmput and mm_release. 627 * mmput is called whenever we stop holding onto a mm_struct, 628 * error success whatever. 629 * 630 * mm_release is called after a mm_struct has been removed 631 * from the current process. 632 * 633 * This difference is important for error handling, when we 634 * only half set up a mm_struct for a new process and need to restore 635 * the old one. Because we mmput the new mm_struct before 636 * restoring the old one. . . 637 * Eric Biederman 10 January 1998 638 */ 639 void mm_release(struct task_struct *tsk, struct mm_struct *mm) 640 { 641 struct completion *vfork_done = tsk->vfork_done; 642 643 /* Get rid of any futexes when releasing the mm */ 644 #ifdef CONFIG_FUTEX 645 if (unlikely(tsk->robust_list)) { 646 exit_robust_list(tsk); 647 tsk->robust_list = NULL; 648 } 649 #ifdef CONFIG_COMPAT 650 if (unlikely(tsk->compat_robust_list)) { 651 compat_exit_robust_list(tsk); 652 tsk->compat_robust_list = NULL; 653 } 654 #endif 655 if (unlikely(!list_empty(&tsk->pi_state_list))) 656 exit_pi_state_list(tsk); 657 #endif 658 659 /* Get rid of any cached register state */ 660 deactivate_mm(tsk, mm); 661 662 /* notify parent sleeping on vfork() */ 663 if (vfork_done) { 664 tsk->vfork_done = NULL; 665 complete(vfork_done); 666 } 667 668 /* 669 * If we're exiting normally, clear a user-space tid field if 670 * requested. We leave this alone when dying by signal, to leave 671 * the value intact in a core dump, and to save the unnecessary 672 * trouble otherwise. Userland only wants this done for a sys_exit. 673 */ 674 if (tsk->clear_child_tid) { 675 if (!(tsk->flags & PF_SIGNALED) && 676 atomic_read(&mm->mm_users) > 1) { 677 /* 678 * We don't check the error code - if userspace has 679 * not set up a proper pointer then tough luck. 680 */ 681 put_user(0, tsk->clear_child_tid); 682 sys_futex(tsk->clear_child_tid, FUTEX_WAKE, 683 1, NULL, NULL, 0); 684 } 685 tsk->clear_child_tid = NULL; 686 } 687 } 688 689 /* 690 * Allocate a new mm structure and copy contents from the 691 * mm structure of the passed in task structure. 692 */ 693 struct mm_struct *dup_mm(struct task_struct *tsk) 694 { 695 struct mm_struct *mm, *oldmm = current->mm; 696 int err; 697 698 if (!oldmm) 699 return NULL; 700 701 mm = allocate_mm(); 702 if (!mm) 703 goto fail_nomem; 704 705 memcpy(mm, oldmm, sizeof(*mm)); 706 707 /* Initializing for Swap token stuff */ 708 mm->token_priority = 0; 709 mm->last_interval = 0; 710 711 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 712 mm->pmd_huge_pte = NULL; 713 #endif 714 715 if (!mm_init(mm, tsk)) 716 goto fail_nomem; 717 718 if (mm_init_cpumask(mm, oldmm)) 719 goto fail_nocpumask; 720 721 if (init_new_context(tsk, mm)) 722 goto fail_nocontext; 723 724 dup_mm_exe_file(oldmm, mm); 725 726 err = dup_mmap(mm, oldmm); 727 if (err) 728 goto free_pt; 729 730 mm->hiwater_rss = get_mm_rss(mm); 731 mm->hiwater_vm = mm->total_vm; 732 733 if (mm->binfmt && !try_module_get(mm->binfmt->module)) 734 goto free_pt; 735 736 return mm; 737 738 free_pt: 739 /* don't put binfmt in mmput, we haven't got module yet */ 740 mm->binfmt = NULL; 741 mmput(mm); 742 743 fail_nomem: 744 return NULL; 745 746 fail_nocontext: 747 free_cpumask_var(mm->cpu_vm_mask_var); 748 749 fail_nocpumask: 750 /* 751 * If init_new_context() failed, we cannot use mmput() to free the mm 752 * because it calls destroy_context() 753 */ 754 mm_free_pgd(mm); 755 free_mm(mm); 756 return NULL; 757 } 758 759 static int copy_mm(unsigned long clone_flags, struct task_struct * tsk) 760 { 761 struct mm_struct * mm, *oldmm; 762 int retval; 763 764 tsk->min_flt = tsk->maj_flt = 0; 765 tsk->nvcsw = tsk->nivcsw = 0; 766 #ifdef CONFIG_DETECT_HUNG_TASK 767 tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw; 768 #endif 769 770 tsk->mm = NULL; 771 tsk->active_mm = NULL; 772 773 /* 774 * Are we cloning a kernel thread? 775 * 776 * We need to steal a active VM for that.. 777 */ 778 oldmm = current->mm; 779 if (!oldmm) 780 return 0; 781 782 if (clone_flags & CLONE_VM) { 783 atomic_inc(&oldmm->mm_users); 784 mm = oldmm; 785 goto good_mm; 786 } 787 788 retval = -ENOMEM; 789 mm = dup_mm(tsk); 790 if (!mm) 791 goto fail_nomem; 792 793 good_mm: 794 /* Initializing for Swap token stuff */ 795 mm->token_priority = 0; 796 mm->last_interval = 0; 797 if (tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) 798 atomic_inc(&mm->oom_disable_count); 799 800 tsk->mm = mm; 801 tsk->active_mm = mm; 802 return 0; 803 804 fail_nomem: 805 return retval; 806 } 807 808 static int copy_fs(unsigned long clone_flags, struct task_struct *tsk) 809 { 810 struct fs_struct *fs = current->fs; 811 if (clone_flags & CLONE_FS) { 812 /* tsk->fs is already what we want */ 813 spin_lock(&fs->lock); 814 if (fs->in_exec) { 815 spin_unlock(&fs->lock); 816 return -EAGAIN; 817 } 818 fs->users++; 819 spin_unlock(&fs->lock); 820 return 0; 821 } 822 tsk->fs = copy_fs_struct(fs); 823 if (!tsk->fs) 824 return -ENOMEM; 825 return 0; 826 } 827 828 static int copy_files(unsigned long clone_flags, struct task_struct * tsk) 829 { 830 struct files_struct *oldf, *newf; 831 int error = 0; 832 833 /* 834 * A background process may not have any files ... 835 */ 836 oldf = current->files; 837 if (!oldf) 838 goto out; 839 840 if (clone_flags & CLONE_FILES) { 841 atomic_inc(&oldf->count); 842 goto out; 843 } 844 845 newf = dup_fd(oldf, &error); 846 if (!newf) 847 goto out; 848 849 tsk->files = newf; 850 error = 0; 851 out: 852 return error; 853 } 854 855 static int copy_io(unsigned long clone_flags, struct task_struct *tsk) 856 { 857 #ifdef CONFIG_BLOCK 858 struct io_context *ioc = current->io_context; 859 860 if (!ioc) 861 return 0; 862 /* 863 * Share io context with parent, if CLONE_IO is set 864 */ 865 if (clone_flags & CLONE_IO) { 866 tsk->io_context = ioc_task_link(ioc); 867 if (unlikely(!tsk->io_context)) 868 return -ENOMEM; 869 } else if (ioprio_valid(ioc->ioprio)) { 870 tsk->io_context = alloc_io_context(GFP_KERNEL, -1); 871 if (unlikely(!tsk->io_context)) 872 return -ENOMEM; 873 874 tsk->io_context->ioprio = ioc->ioprio; 875 } 876 #endif 877 return 0; 878 } 879 880 static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk) 881 { 882 struct sighand_struct *sig; 883 884 if (clone_flags & CLONE_SIGHAND) { 885 atomic_inc(¤t->sighand->count); 886 return 0; 887 } 888 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); 889 rcu_assign_pointer(tsk->sighand, sig); 890 if (!sig) 891 return -ENOMEM; 892 atomic_set(&sig->count, 1); 893 memcpy(sig->action, current->sighand->action, sizeof(sig->action)); 894 return 0; 895 } 896 897 void __cleanup_sighand(struct sighand_struct *sighand) 898 { 899 if (atomic_dec_and_test(&sighand->count)) 900 kmem_cache_free(sighand_cachep, sighand); 901 } 902 903 904 /* 905 * Initialize POSIX timer handling for a thread group. 906 */ 907 static void posix_cpu_timers_init_group(struct signal_struct *sig) 908 { 909 unsigned long cpu_limit; 910 911 /* Thread group counters. */ 912 thread_group_cputime_init(sig); 913 914 cpu_limit = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur); 915 if (cpu_limit != RLIM_INFINITY) { 916 sig->cputime_expires.prof_exp = secs_to_cputime(cpu_limit); 917 sig->cputimer.running = 1; 918 } 919 920 /* The timer lists. */ 921 INIT_LIST_HEAD(&sig->cpu_timers[0]); 922 INIT_LIST_HEAD(&sig->cpu_timers[1]); 923 INIT_LIST_HEAD(&sig->cpu_timers[2]); 924 } 925 926 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) 927 { 928 struct signal_struct *sig; 929 930 if (clone_flags & CLONE_THREAD) 931 return 0; 932 933 sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL); 934 tsk->signal = sig; 935 if (!sig) 936 return -ENOMEM; 937 938 sig->nr_threads = 1; 939 atomic_set(&sig->live, 1); 940 atomic_set(&sig->sigcnt, 1); 941 init_waitqueue_head(&sig->wait_chldexit); 942 if (clone_flags & CLONE_NEWPID) 943 sig->flags |= SIGNAL_UNKILLABLE; 944 sig->curr_target = tsk; 945 init_sigpending(&sig->shared_pending); 946 INIT_LIST_HEAD(&sig->posix_timers); 947 948 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 949 sig->real_timer.function = it_real_fn; 950 951 task_lock(current->group_leader); 952 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim); 953 task_unlock(current->group_leader); 954 955 posix_cpu_timers_init_group(sig); 956 957 tty_audit_fork(sig); 958 sched_autogroup_fork(sig); 959 960 #ifdef CONFIG_CGROUPS 961 init_rwsem(&sig->threadgroup_fork_lock); 962 #endif 963 964 sig->oom_adj = current->signal->oom_adj; 965 sig->oom_score_adj = current->signal->oom_score_adj; 966 sig->oom_score_adj_min = current->signal->oom_score_adj_min; 967 968 mutex_init(&sig->cred_guard_mutex); 969 970 return 0; 971 } 972 973 static void copy_flags(unsigned long clone_flags, struct task_struct *p) 974 { 975 unsigned long new_flags = p->flags; 976 977 new_flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER); 978 new_flags |= PF_FORKNOEXEC; 979 new_flags |= PF_STARTING; 980 p->flags = new_flags; 981 clear_freeze_flag(p); 982 } 983 984 SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr) 985 { 986 current->clear_child_tid = tidptr; 987 988 return task_pid_vnr(current); 989 } 990 991 static void rt_mutex_init_task(struct task_struct *p) 992 { 993 raw_spin_lock_init(&p->pi_lock); 994 #ifdef CONFIG_RT_MUTEXES 995 plist_head_init_raw(&p->pi_waiters, &p->pi_lock); 996 p->pi_blocked_on = NULL; 997 #endif 998 } 999 1000 #ifdef CONFIG_MM_OWNER 1001 void mm_init_owner(struct mm_struct *mm, struct task_struct *p) 1002 { 1003 mm->owner = p; 1004 } 1005 #endif /* CONFIG_MM_OWNER */ 1006 1007 /* 1008 * Initialize POSIX timer handling for a single task. 1009 */ 1010 static void posix_cpu_timers_init(struct task_struct *tsk) 1011 { 1012 tsk->cputime_expires.prof_exp = cputime_zero; 1013 tsk->cputime_expires.virt_exp = cputime_zero; 1014 tsk->cputime_expires.sched_exp = 0; 1015 INIT_LIST_HEAD(&tsk->cpu_timers[0]); 1016 INIT_LIST_HEAD(&tsk->cpu_timers[1]); 1017 INIT_LIST_HEAD(&tsk->cpu_timers[2]); 1018 } 1019 1020 /* 1021 * This creates a new process as a copy of the old one, 1022 * but does not actually start it yet. 1023 * 1024 * It copies the registers, and all the appropriate 1025 * parts of the process environment (as per the clone 1026 * flags). The actual kick-off is left to the caller. 1027 */ 1028 static struct task_struct *copy_process(unsigned long clone_flags, 1029 unsigned long stack_start, 1030 struct pt_regs *regs, 1031 unsigned long stack_size, 1032 int __user *child_tidptr, 1033 struct pid *pid, 1034 int trace) 1035 { 1036 int retval; 1037 struct task_struct *p; 1038 int cgroup_callbacks_done = 0; 1039 1040 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) 1041 return ERR_PTR(-EINVAL); 1042 1043 /* 1044 * Thread groups must share signals as well, and detached threads 1045 * can only be started up within the thread group. 1046 */ 1047 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND)) 1048 return ERR_PTR(-EINVAL); 1049 1050 /* 1051 * Shared signal handlers imply shared VM. By way of the above, 1052 * thread groups also imply shared VM. Blocking this case allows 1053 * for various simplifications in other code. 1054 */ 1055 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) 1056 return ERR_PTR(-EINVAL); 1057 1058 /* 1059 * Siblings of global init remain as zombies on exit since they are 1060 * not reaped by their parent (swapper). To solve this and to avoid 1061 * multi-rooted process trees, prevent global and container-inits 1062 * from creating siblings. 1063 */ 1064 if ((clone_flags & CLONE_PARENT) && 1065 current->signal->flags & SIGNAL_UNKILLABLE) 1066 return ERR_PTR(-EINVAL); 1067 1068 retval = security_task_create(clone_flags); 1069 if (retval) 1070 goto fork_out; 1071 1072 retval = -ENOMEM; 1073 p = dup_task_struct(current); 1074 if (!p) 1075 goto fork_out; 1076 1077 ftrace_graph_init_task(p); 1078 1079 rt_mutex_init_task(p); 1080 1081 #ifdef CONFIG_PROVE_LOCKING 1082 DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled); 1083 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled); 1084 #endif 1085 retval = -EAGAIN; 1086 if (atomic_read(&p->real_cred->user->processes) >= 1087 task_rlimit(p, RLIMIT_NPROC)) { 1088 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) && 1089 p->real_cred->user != INIT_USER) 1090 goto bad_fork_free; 1091 } 1092 1093 retval = copy_creds(p, clone_flags); 1094 if (retval < 0) 1095 goto bad_fork_free; 1096 1097 /* 1098 * If multiple threads are within copy_process(), then this check 1099 * triggers too late. This doesn't hurt, the check is only there 1100 * to stop root fork bombs. 1101 */ 1102 retval = -EAGAIN; 1103 if (nr_threads >= max_threads) 1104 goto bad_fork_cleanup_count; 1105 1106 if (!try_module_get(task_thread_info(p)->exec_domain->module)) 1107 goto bad_fork_cleanup_count; 1108 1109 p->did_exec = 0; 1110 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */ 1111 copy_flags(clone_flags, p); 1112 INIT_LIST_HEAD(&p->children); 1113 INIT_LIST_HEAD(&p->sibling); 1114 rcu_copy_process(p); 1115 p->vfork_done = NULL; 1116 spin_lock_init(&p->alloc_lock); 1117 1118 init_sigpending(&p->pending); 1119 1120 p->utime = cputime_zero; 1121 p->stime = cputime_zero; 1122 p->gtime = cputime_zero; 1123 p->utimescaled = cputime_zero; 1124 p->stimescaled = cputime_zero; 1125 #ifndef CONFIG_VIRT_CPU_ACCOUNTING 1126 p->prev_utime = cputime_zero; 1127 p->prev_stime = cputime_zero; 1128 #endif 1129 #if defined(SPLIT_RSS_COUNTING) 1130 memset(&p->rss_stat, 0, sizeof(p->rss_stat)); 1131 #endif 1132 1133 p->default_timer_slack_ns = current->timer_slack_ns; 1134 1135 task_io_accounting_init(&p->ioac); 1136 acct_clear_integrals(p); 1137 1138 posix_cpu_timers_init(p); 1139 1140 do_posix_clock_monotonic_gettime(&p->start_time); 1141 p->real_start_time = p->start_time; 1142 monotonic_to_bootbased(&p->real_start_time); 1143 p->io_context = NULL; 1144 p->audit_context = NULL; 1145 if (clone_flags & CLONE_THREAD) 1146 threadgroup_fork_read_lock(current); 1147 cgroup_fork(p); 1148 #ifdef CONFIG_NUMA 1149 p->mempolicy = mpol_dup(p->mempolicy); 1150 if (IS_ERR(p->mempolicy)) { 1151 retval = PTR_ERR(p->mempolicy); 1152 p->mempolicy = NULL; 1153 goto bad_fork_cleanup_cgroup; 1154 } 1155 mpol_fix_fork_child_flag(p); 1156 #endif 1157 #ifdef CONFIG_TRACE_IRQFLAGS 1158 p->irq_events = 0; 1159 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW 1160 p->hardirqs_enabled = 1; 1161 #else 1162 p->hardirqs_enabled = 0; 1163 #endif 1164 p->hardirq_enable_ip = 0; 1165 p->hardirq_enable_event = 0; 1166 p->hardirq_disable_ip = _THIS_IP_; 1167 p->hardirq_disable_event = 0; 1168 p->softirqs_enabled = 1; 1169 p->softirq_enable_ip = _THIS_IP_; 1170 p->softirq_enable_event = 0; 1171 p->softirq_disable_ip = 0; 1172 p->softirq_disable_event = 0; 1173 p->hardirq_context = 0; 1174 p->softirq_context = 0; 1175 #endif 1176 #ifdef CONFIG_LOCKDEP 1177 p->lockdep_depth = 0; /* no locks held yet */ 1178 p->curr_chain_key = 0; 1179 p->lockdep_recursion = 0; 1180 #endif 1181 1182 #ifdef CONFIG_DEBUG_MUTEXES 1183 p->blocked_on = NULL; /* not blocked yet */ 1184 #endif 1185 #ifdef CONFIG_CGROUP_MEM_RES_CTLR 1186 p->memcg_batch.do_batch = 0; 1187 p->memcg_batch.memcg = NULL; 1188 #endif 1189 1190 /* Perform scheduler related setup. Assign this task to a CPU. */ 1191 sched_fork(p); 1192 1193 retval = perf_event_init_task(p); 1194 if (retval) 1195 goto bad_fork_cleanup_policy; 1196 1197 if ((retval = audit_alloc(p))) 1198 goto bad_fork_cleanup_policy; 1199 /* copy all the process information */ 1200 if ((retval = copy_semundo(clone_flags, p))) 1201 goto bad_fork_cleanup_audit; 1202 if ((retval = copy_files(clone_flags, p))) 1203 goto bad_fork_cleanup_semundo; 1204 if ((retval = copy_fs(clone_flags, p))) 1205 goto bad_fork_cleanup_files; 1206 if ((retval = copy_sighand(clone_flags, p))) 1207 goto bad_fork_cleanup_fs; 1208 if ((retval = copy_signal(clone_flags, p))) 1209 goto bad_fork_cleanup_sighand; 1210 if ((retval = copy_mm(clone_flags, p))) 1211 goto bad_fork_cleanup_signal; 1212 if ((retval = copy_namespaces(clone_flags, p))) 1213 goto bad_fork_cleanup_mm; 1214 if ((retval = copy_io(clone_flags, p))) 1215 goto bad_fork_cleanup_namespaces; 1216 retval = copy_thread(clone_flags, stack_start, stack_size, p, regs); 1217 if (retval) 1218 goto bad_fork_cleanup_io; 1219 1220 if (pid != &init_struct_pid) { 1221 retval = -ENOMEM; 1222 pid = alloc_pid(p->nsproxy->pid_ns); 1223 if (!pid) 1224 goto bad_fork_cleanup_io; 1225 } 1226 1227 p->pid = pid_nr(pid); 1228 p->tgid = p->pid; 1229 if (clone_flags & CLONE_THREAD) 1230 p->tgid = current->tgid; 1231 1232 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL; 1233 /* 1234 * Clear TID on mm_release()? 1235 */ 1236 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL; 1237 #ifdef CONFIG_BLOCK 1238 p->plug = NULL; 1239 #endif 1240 #ifdef CONFIG_FUTEX 1241 p->robust_list = NULL; 1242 #ifdef CONFIG_COMPAT 1243 p->compat_robust_list = NULL; 1244 #endif 1245 INIT_LIST_HEAD(&p->pi_state_list); 1246 p->pi_state_cache = NULL; 1247 #endif 1248 /* 1249 * sigaltstack should be cleared when sharing the same VM 1250 */ 1251 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM) 1252 p->sas_ss_sp = p->sas_ss_size = 0; 1253 1254 /* 1255 * Syscall tracing and stepping should be turned off in the 1256 * child regardless of CLONE_PTRACE. 1257 */ 1258 user_disable_single_step(p); 1259 clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE); 1260 #ifdef TIF_SYSCALL_EMU 1261 clear_tsk_thread_flag(p, TIF_SYSCALL_EMU); 1262 #endif 1263 clear_all_latency_tracing(p); 1264 1265 /* ok, now we should be set up.. */ 1266 p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL); 1267 p->pdeath_signal = 0; 1268 p->exit_state = 0; 1269 1270 /* 1271 * Ok, make it visible to the rest of the system. 1272 * We dont wake it up yet. 1273 */ 1274 p->group_leader = p; 1275 INIT_LIST_HEAD(&p->thread_group); 1276 1277 /* Now that the task is set up, run cgroup callbacks if 1278 * necessary. We need to run them before the task is visible 1279 * on the tasklist. */ 1280 cgroup_fork_callbacks(p); 1281 cgroup_callbacks_done = 1; 1282 1283 /* Need tasklist lock for parent etc handling! */ 1284 write_lock_irq(&tasklist_lock); 1285 1286 /* CLONE_PARENT re-uses the old parent */ 1287 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) { 1288 p->real_parent = current->real_parent; 1289 p->parent_exec_id = current->parent_exec_id; 1290 } else { 1291 p->real_parent = current; 1292 p->parent_exec_id = current->self_exec_id; 1293 } 1294 1295 spin_lock(¤t->sighand->siglock); 1296 1297 /* 1298 * Process group and session signals need to be delivered to just the 1299 * parent before the fork or both the parent and the child after the 1300 * fork. Restart if a signal comes in before we add the new process to 1301 * it's process group. 1302 * A fatal signal pending means that current will exit, so the new 1303 * thread can't slip out of an OOM kill (or normal SIGKILL). 1304 */ 1305 recalc_sigpending(); 1306 if (signal_pending(current)) { 1307 spin_unlock(¤t->sighand->siglock); 1308 write_unlock_irq(&tasklist_lock); 1309 retval = -ERESTARTNOINTR; 1310 goto bad_fork_free_pid; 1311 } 1312 1313 if (clone_flags & CLONE_THREAD) { 1314 current->signal->nr_threads++; 1315 atomic_inc(¤t->signal->live); 1316 atomic_inc(¤t->signal->sigcnt); 1317 p->group_leader = current->group_leader; 1318 list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group); 1319 } 1320 1321 if (likely(p->pid)) { 1322 tracehook_finish_clone(p, clone_flags, trace); 1323 1324 if (thread_group_leader(p)) { 1325 if (is_child_reaper(pid)) 1326 p->nsproxy->pid_ns->child_reaper = p; 1327 1328 p->signal->leader_pid = pid; 1329 p->signal->tty = tty_kref_get(current->signal->tty); 1330 attach_pid(p, PIDTYPE_PGID, task_pgrp(current)); 1331 attach_pid(p, PIDTYPE_SID, task_session(current)); 1332 list_add_tail(&p->sibling, &p->real_parent->children); 1333 list_add_tail_rcu(&p->tasks, &init_task.tasks); 1334 __this_cpu_inc(process_counts); 1335 } 1336 attach_pid(p, PIDTYPE_PID, pid); 1337 nr_threads++; 1338 } 1339 1340 total_forks++; 1341 spin_unlock(¤t->sighand->siglock); 1342 write_unlock_irq(&tasklist_lock); 1343 proc_fork_connector(p); 1344 cgroup_post_fork(p); 1345 if (clone_flags & CLONE_THREAD) 1346 threadgroup_fork_read_unlock(current); 1347 perf_event_fork(p); 1348 return p; 1349 1350 bad_fork_free_pid: 1351 if (pid != &init_struct_pid) 1352 free_pid(pid); 1353 bad_fork_cleanup_io: 1354 if (p->io_context) 1355 exit_io_context(p); 1356 bad_fork_cleanup_namespaces: 1357 exit_task_namespaces(p); 1358 bad_fork_cleanup_mm: 1359 if (p->mm) { 1360 task_lock(p); 1361 if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) 1362 atomic_dec(&p->mm->oom_disable_count); 1363 task_unlock(p); 1364 mmput(p->mm); 1365 } 1366 bad_fork_cleanup_signal: 1367 if (!(clone_flags & CLONE_THREAD)) 1368 free_signal_struct(p->signal); 1369 bad_fork_cleanup_sighand: 1370 __cleanup_sighand(p->sighand); 1371 bad_fork_cleanup_fs: 1372 exit_fs(p); /* blocking */ 1373 bad_fork_cleanup_files: 1374 exit_files(p); /* blocking */ 1375 bad_fork_cleanup_semundo: 1376 exit_sem(p); 1377 bad_fork_cleanup_audit: 1378 audit_free(p); 1379 bad_fork_cleanup_policy: 1380 perf_event_free_task(p); 1381 #ifdef CONFIG_NUMA 1382 mpol_put(p->mempolicy); 1383 bad_fork_cleanup_cgroup: 1384 #endif 1385 if (clone_flags & CLONE_THREAD) 1386 threadgroup_fork_read_unlock(current); 1387 cgroup_exit(p, cgroup_callbacks_done); 1388 delayacct_tsk_free(p); 1389 module_put(task_thread_info(p)->exec_domain->module); 1390 bad_fork_cleanup_count: 1391 atomic_dec(&p->cred->user->processes); 1392 exit_creds(p); 1393 bad_fork_free: 1394 free_task(p); 1395 fork_out: 1396 return ERR_PTR(retval); 1397 } 1398 1399 noinline struct pt_regs * __cpuinit __attribute__((weak)) idle_regs(struct pt_regs *regs) 1400 { 1401 memset(regs, 0, sizeof(struct pt_regs)); 1402 return regs; 1403 } 1404 1405 static inline void init_idle_pids(struct pid_link *links) 1406 { 1407 enum pid_type type; 1408 1409 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) { 1410 INIT_HLIST_NODE(&links[type].node); /* not really needed */ 1411 links[type].pid = &init_struct_pid; 1412 } 1413 } 1414 1415 struct task_struct * __cpuinit fork_idle(int cpu) 1416 { 1417 struct task_struct *task; 1418 struct pt_regs regs; 1419 1420 task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL, 1421 &init_struct_pid, 0); 1422 if (!IS_ERR(task)) { 1423 init_idle_pids(task->pids); 1424 init_idle(task, cpu); 1425 } 1426 1427 return task; 1428 } 1429 1430 /* 1431 * Ok, this is the main fork-routine. 1432 * 1433 * It copies the process, and if successful kick-starts 1434 * it and waits for it to finish using the VM if required. 1435 */ 1436 long do_fork(unsigned long clone_flags, 1437 unsigned long stack_start, 1438 struct pt_regs *regs, 1439 unsigned long stack_size, 1440 int __user *parent_tidptr, 1441 int __user *child_tidptr) 1442 { 1443 struct task_struct *p; 1444 int trace = 0; 1445 long nr; 1446 1447 /* 1448 * Do some preliminary argument and permissions checking before we 1449 * actually start allocating stuff 1450 */ 1451 if (clone_flags & CLONE_NEWUSER) { 1452 if (clone_flags & CLONE_THREAD) 1453 return -EINVAL; 1454 /* hopefully this check will go away when userns support is 1455 * complete 1456 */ 1457 if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SETUID) || 1458 !capable(CAP_SETGID)) 1459 return -EPERM; 1460 } 1461 1462 /* 1463 * When called from kernel_thread, don't do user tracing stuff. 1464 */ 1465 if (likely(user_mode(regs))) 1466 trace = tracehook_prepare_clone(clone_flags); 1467 1468 p = copy_process(clone_flags, stack_start, regs, stack_size, 1469 child_tidptr, NULL, trace); 1470 /* 1471 * Do this prior waking up the new thread - the thread pointer 1472 * might get invalid after that point, if the thread exits quickly. 1473 */ 1474 if (!IS_ERR(p)) { 1475 struct completion vfork; 1476 1477 trace_sched_process_fork(current, p); 1478 1479 nr = task_pid_vnr(p); 1480 1481 if (clone_flags & CLONE_PARENT_SETTID) 1482 put_user(nr, parent_tidptr); 1483 1484 if (clone_flags & CLONE_VFORK) { 1485 p->vfork_done = &vfork; 1486 init_completion(&vfork); 1487 } 1488 1489 audit_finish_fork(p); 1490 tracehook_report_clone(regs, clone_flags, nr, p); 1491 1492 /* 1493 * We set PF_STARTING at creation in case tracing wants to 1494 * use this to distinguish a fully live task from one that 1495 * hasn't gotten to tracehook_report_clone() yet. Now we 1496 * clear it and set the child going. 1497 */ 1498 p->flags &= ~PF_STARTING; 1499 1500 wake_up_new_task(p); 1501 1502 tracehook_report_clone_complete(trace, regs, 1503 clone_flags, nr, p); 1504 1505 if (clone_flags & CLONE_VFORK) { 1506 freezer_do_not_count(); 1507 wait_for_completion(&vfork); 1508 freezer_count(); 1509 tracehook_report_vfork_done(p, nr); 1510 } 1511 } else { 1512 nr = PTR_ERR(p); 1513 } 1514 return nr; 1515 } 1516 1517 #ifndef ARCH_MIN_MMSTRUCT_ALIGN 1518 #define ARCH_MIN_MMSTRUCT_ALIGN 0 1519 #endif 1520 1521 static void sighand_ctor(void *data) 1522 { 1523 struct sighand_struct *sighand = data; 1524 1525 spin_lock_init(&sighand->siglock); 1526 init_waitqueue_head(&sighand->signalfd_wqh); 1527 } 1528 1529 void __init proc_caches_init(void) 1530 { 1531 sighand_cachep = kmem_cache_create("sighand_cache", 1532 sizeof(struct sighand_struct), 0, 1533 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU| 1534 SLAB_NOTRACK, sighand_ctor); 1535 signal_cachep = kmem_cache_create("signal_cache", 1536 sizeof(struct signal_struct), 0, 1537 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); 1538 files_cachep = kmem_cache_create("files_cache", 1539 sizeof(struct files_struct), 0, 1540 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); 1541 fs_cachep = kmem_cache_create("fs_cache", 1542 sizeof(struct fs_struct), 0, 1543 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); 1544 mm_cachep = kmem_cache_create("mm_struct", 1545 sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN, 1546 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); 1547 vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC); 1548 mmap_init(); 1549 } 1550 1551 /* 1552 * Check constraints on flags passed to the unshare system call. 1553 */ 1554 static int check_unshare_flags(unsigned long unshare_flags) 1555 { 1556 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND| 1557 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM| 1558 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET)) 1559 return -EINVAL; 1560 /* 1561 * Not implemented, but pretend it works if there is nothing to 1562 * unshare. Note that unsharing CLONE_THREAD or CLONE_SIGHAND 1563 * needs to unshare vm. 1564 */ 1565 if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) { 1566 /* FIXME: get_task_mm() increments ->mm_users */ 1567 if (atomic_read(¤t->mm->mm_users) > 1) 1568 return -EINVAL; 1569 } 1570 1571 return 0; 1572 } 1573 1574 /* 1575 * Unshare the filesystem structure if it is being shared 1576 */ 1577 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp) 1578 { 1579 struct fs_struct *fs = current->fs; 1580 1581 if (!(unshare_flags & CLONE_FS) || !fs) 1582 return 0; 1583 1584 /* don't need lock here; in the worst case we'll do useless copy */ 1585 if (fs->users == 1) 1586 return 0; 1587 1588 *new_fsp = copy_fs_struct(fs); 1589 if (!*new_fsp) 1590 return -ENOMEM; 1591 1592 return 0; 1593 } 1594 1595 /* 1596 * Unshare file descriptor table if it is being shared 1597 */ 1598 static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp) 1599 { 1600 struct files_struct *fd = current->files; 1601 int error = 0; 1602 1603 if ((unshare_flags & CLONE_FILES) && 1604 (fd && atomic_read(&fd->count) > 1)) { 1605 *new_fdp = dup_fd(fd, &error); 1606 if (!*new_fdp) 1607 return error; 1608 } 1609 1610 return 0; 1611 } 1612 1613 /* 1614 * unshare allows a process to 'unshare' part of the process 1615 * context which was originally shared using clone. copy_* 1616 * functions used by do_fork() cannot be used here directly 1617 * because they modify an inactive task_struct that is being 1618 * constructed. Here we are modifying the current, active, 1619 * task_struct. 1620 */ 1621 SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags) 1622 { 1623 struct fs_struct *fs, *new_fs = NULL; 1624 struct files_struct *fd, *new_fd = NULL; 1625 struct nsproxy *new_nsproxy = NULL; 1626 int do_sysvsem = 0; 1627 int err; 1628 1629 err = check_unshare_flags(unshare_flags); 1630 if (err) 1631 goto bad_unshare_out; 1632 1633 /* 1634 * If unsharing namespace, must also unshare filesystem information. 1635 */ 1636 if (unshare_flags & CLONE_NEWNS) 1637 unshare_flags |= CLONE_FS; 1638 /* 1639 * CLONE_NEWIPC must also detach from the undolist: after switching 1640 * to a new ipc namespace, the semaphore arrays from the old 1641 * namespace are unreachable. 1642 */ 1643 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM)) 1644 do_sysvsem = 1; 1645 if ((err = unshare_fs(unshare_flags, &new_fs))) 1646 goto bad_unshare_out; 1647 if ((err = unshare_fd(unshare_flags, &new_fd))) 1648 goto bad_unshare_cleanup_fs; 1649 if ((err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy, 1650 new_fs))) 1651 goto bad_unshare_cleanup_fd; 1652 1653 if (new_fs || new_fd || do_sysvsem || new_nsproxy) { 1654 if (do_sysvsem) { 1655 /* 1656 * CLONE_SYSVSEM is equivalent to sys_exit(). 1657 */ 1658 exit_sem(current); 1659 } 1660 1661 if (new_nsproxy) { 1662 switch_task_namespaces(current, new_nsproxy); 1663 new_nsproxy = NULL; 1664 } 1665 1666 task_lock(current); 1667 1668 if (new_fs) { 1669 fs = current->fs; 1670 spin_lock(&fs->lock); 1671 current->fs = new_fs; 1672 if (--fs->users) 1673 new_fs = NULL; 1674 else 1675 new_fs = fs; 1676 spin_unlock(&fs->lock); 1677 } 1678 1679 if (new_fd) { 1680 fd = current->files; 1681 current->files = new_fd; 1682 new_fd = fd; 1683 } 1684 1685 task_unlock(current); 1686 } 1687 1688 if (new_nsproxy) 1689 put_nsproxy(new_nsproxy); 1690 1691 bad_unshare_cleanup_fd: 1692 if (new_fd) 1693 put_files_struct(new_fd); 1694 1695 bad_unshare_cleanup_fs: 1696 if (new_fs) 1697 free_fs_struct(new_fs); 1698 1699 bad_unshare_out: 1700 return err; 1701 } 1702 1703 /* 1704 * Helper to unshare the files of the current task. 1705 * We don't want to expose copy_files internals to 1706 * the exec layer of the kernel. 1707 */ 1708 1709 int unshare_files(struct files_struct **displaced) 1710 { 1711 struct task_struct *task = current; 1712 struct files_struct *copy = NULL; 1713 int error; 1714 1715 error = unshare_fd(CLONE_FILES, ©); 1716 if (error || !copy) { 1717 *displaced = NULL; 1718 return error; 1719 } 1720 *displaced = task->files; 1721 task_lock(task); 1722 task->files = copy; 1723 task_unlock(task); 1724 return 0; 1725 } 1726