/*

* 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>

#include <linux/personality.h>

#include <linux/mempolicy.h>

#include <linux/sem.h>

#include <linux/file.h>

#include <linux/fdtable.h>

#include <linux/iocontext.h>

#include <linux/key.h>

#include <linux/binfmts.h>

#include <linux/mman.h>

#include <linux/mmu_notifier.h>

#include <linux/fs.h>

#include <linux/mm.h>

#include <linux/vmacache.h>

#include <linux/nsproxy.h>

#include <linux/capability.h>

#include <linux/cpu.h>

#include <linux/cgroup.h>

#include <linux/security.h>

#include <linux/hugetlb.h>

#include <linux/seccomp.h>

#include <linux/swap.h>

#include <linux/syscalls.h>

#include <linux/jiffies.h>

#include <linux/futex.h>

#include <linux/compat.h>

#include <linux/kthread.h>

#include <linux/task_io_accounting_ops.h>

#include <linux/rcupdate.h>

#include <linux/ptrace.h>

#include <linux/mount.h>

#include <linux/audit.h>

#include <linux/memcontrol.h>

#include <linux/ftrace.h>

#include <linux/proc_fs.h>

#include <linux/profile.h>

#include <linux/rmap.h>

#include <linux/ksm.h>

#include <linux/acct.h>

#include <linux/tsacct_kern.h>

#include <linux/cn_proc.h>

#include <linux/freezer.h>

#include <linux/delayacct.h>

#include <linux/taskstats_kern.h>

#include <linux/random.h>

#include <linux/tty.h>

#include <linux/blkdev.h>

#include <linux/fs_struct.h>

#include <linux/magic.h>

#include <linux/perf_event.h>

#include <linux/posix-timers.h>

#include <linux/user-return-notifier.h>

#include <linux/oom.h>

#include <linux/khugepaged.h>

#include <linux/signalfd.h>

#include <linux/uprobes.h>

#include <linux/aio.h>

#include <linux/compiler.h>

#include <linux/sysctl.h>

#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>

#include <trace/events/sched.h>

#define CREATE_TRACE_POINTS

#include <trace/events/task.h>

/*

* Minimum number of threads to boot the kernel

*/

#define MIN_THREADS 20

/*

* Maximum number of threads

*/

#define MAX_THREADS FUTEX_TID_MASK

/*

* 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;

__cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */

#ifdef CONFIG_PROVE_RCU

int lockdep_tasklist_lock_is_held(void)

{

return lockdep_is_held(&tasklist_lock);

}

EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held);

#endif /* #ifdef CONFIG_PROVE_RCU */

int nr_processes(void)

{

int cpu;

int total = 0;

for_each_possible_cpu(cpu)

total += per_cpu(process_counts, cpu);

return total;

}

void __weak arch_release_task_struct(struct task_struct *tsk)

{

}

#ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR

static struct kmem_cache *task_struct_cachep;

static inline struct task_struct *alloc_task_struct_node(int node)

{

return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node);

}

static inline void free_task_struct(struct task_struct *tsk)

{

kmem_cache_free(task_struct_cachep, tsk);

}

#endif

void __weak arch_release_thread_info(struct thread_info *ti)

{

}

#ifndef CONFIG_ARCH_THREAD_INFO_ALLOCATOR

/*

* Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a

* kmemcache based allocator.

*/

# if THREAD_SIZE >= PAGE_SIZE

static struct thread_info *alloc_thread_info_node(struct task_struct *tsk,

int node)

{

struct page *page = alloc_kmem_pages_node(node, THREADINFO_GFP,

THREAD_SIZE_ORDER);

return page ? page_address(page) : NULL;

}

static inline void free_thread_info(struct thread_info *ti)

{

free_kmem_pages((unsigned long)ti, THREAD_SIZE_ORDER);

}

# else

static struct kmem_cache *thread_info_cache;

static struct thread_info *alloc_thread_info_node(struct task_struct *tsk,

int node)

{

return kmem_cache_alloc_node(thread_info_cache, THREADINFO_GFP, node);

}

static void free_thread_info(struct thread_info *ti)

{

kmem_cache_free(thread_info_cache, ti);

}

void thread_info_cache_init(void)

{

thread_info_cache = kmem_cache_create("thread_info", THREAD_SIZE,

THREAD_SIZE, 0, NULL);

BUG_ON(thread_info_cache == NULL);

}

# endif

#endif

/* SLAB cache for signal_struct structures (tsk->signal) */

static struct kmem_cache *signal_cachep;

/* SLAB cache for sighand_struct structures (tsk->sighand) */

struct kmem_cache *sighand_cachep;

/* SLAB cache for files_struct structures (tsk->files) */

struct kmem_cache *files_cachep;

/* SLAB cache for fs_struct structures (tsk->fs) */

struct kmem_cache *fs_cachep;

/* SLAB cache for vm_area_struct structures */

struct kmem_cache *vm_area_cachep;

/* SLAB cache for mm_struct structures (tsk->mm) */

static struct kmem_cache *mm_cachep;

static void account_kernel_stack(struct thread_info *ti, int account)

{

struct zone *zone = page_zone(virt_to_page(ti));

mod_zone_page_state(zone, NR_KERNEL_STACK, account);

}

void free_task(struct task_struct *tsk)

{

account_kernel_stack(tsk->stack, -1);

arch_release_thread_info(tsk->stack);

free_thread_info(tsk->stack);

rt_mutex_debug_task_free(tsk);

ftrace_graph_exit_task(tsk);

put_seccomp_filter(tsk);

arch_release_task_struct(tsk);

free_task_struct(tsk);

}

EXPORT_SYMBOL(free_task);

static inline void free_signal_struct(struct signal_struct *sig)

{

taskstats_tgid_free(sig);

sched_autogroup_exit(sig);

kmem_cache_free(signal_cachep, sig);

}

static inline void put_signal_struct(struct signal_struct *sig)

{

if (atomic_dec_and_test(&sig->sigcnt))

free_signal_struct(sig);

}

void __put_task_struct(struct task_struct *tsk)

{

WARN_ON(!tsk->exit_state);

WARN_ON(atomic_read(&tsk->usage));

WARN_ON(tsk == current);

task_numa_free(tsk);

security_task_free(tsk);

exit_creds(tsk);

delayacct_tsk_free(tsk);

put_signal_struct(tsk->signal);

if (!profile_handoff_task(tsk))

free_task(tsk);

}

EXPORT_SYMBOL_GPL(__put_task_struct);

void __init __weak arch_task_cache_init(void) { }

/*

* set_max_threads

*/

static void set_max_threads(unsigned int max_threads_suggested)

{

u64 threads;

/*

* The number of threads shall be limited such that the thread

* structures may only consume a small part of the available memory.

*/

if (fls64(totalram_pages) + fls64(PAGE_SIZE) > 64)

threads = MAX_THREADS;

else

threads = div64_u64((u64) totalram_pages * (u64) PAGE_SIZE,

(u64) THREAD_SIZE * 8UL);

if (threads > max_threads_suggested)

threads = max_threads_suggested;

max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS);

}

#ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT

/* Initialized by the architecture: */

int arch_task_struct_size __read_mostly;

#endif

void __init fork_init(void)

{

#ifndef CONFIG_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", arch_task_struct_size,

ARCH_MIN_TASKALIGN, SLAB_PANIC | SLAB_NOTRACK, NULL);

#endif

/* do the arch specific task caches init */

arch_task_cache_init();

set_max_threads(MAX_THREADS);

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];

}

int __weak arch_dup_task_struct(struct task_struct *dst,

struct task_struct *src)

{

*dst = *src;

return 0;

}

void set_task_stack_end_magic(struct task_struct *tsk)

{

unsigned long *stackend;

stackend = end_of_stack(tsk);

*stackend = STACK_END_MAGIC; /* for overflow detection */

}

static struct task_struct *dup_task_struct(struct task_struct *orig)

{

struct task_struct *tsk;

struct thread_info *ti;

int node = tsk_fork_get_node(orig);

int err;

tsk = alloc_task_struct_node(node);

if (!tsk)

return NULL;

ti = alloc_thread_info_node(tsk, node);

if (!ti)

goto free_tsk;

err = arch_dup_task_struct(tsk, orig);

if (err)

goto free_ti;

tsk->stack = ti;

#ifdef CONFIG_SECCOMP

/*

* We must handle setting up seccomp filters once we're under

* the sighand lock in case orig has changed between now and

* then. Until then, filter must be NULL to avoid messing up

* the usage counts on the error path calling free_task.

*/

tsk->seccomp.filter = NULL;

#endif

setup_thread_stack(tsk, orig);

clear_user_return_notifier(tsk);

clear_tsk_need_resched(tsk);

set_task_stack_end_magic(tsk);

#ifdef CONFIG_CC_STACKPROTECTOR

tsk->stack_canary = get_random_int();

#endif

/*

* One for us, one for whoever does the "release_task()" (usually

* parent)

*/

atomic_set(&tsk->usage, 2);

#ifdef CONFIG_BLK_DEV_IO_TRACE

tsk->btrace_seq = 0;

#endif

tsk->splice_pipe = NULL;

tsk->task_frag.page = NULL;

account_kernel_stack(ti, 1);

return tsk;

free_ti:

free_thread_info(ti);

free_tsk:

free_task_struct(tsk);

return NULL;

}

#ifdef CONFIG_MMU

static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)

{

struct vm_area_struct *mpnt, *tmp, *prev, **pprev;

struct rb_node **rb_link, *rb_parent;

int retval;

unsigned long charge;

uprobe_start_dup_mmap();

down_write(&oldmm->mmap_sem);

flush_cache_dup_mm(oldmm);

uprobe_dup_mmap(oldmm, mm);

/*

* Not linked in yet - no deadlock potential:

*/

down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);

/* No ordering required: file already has been exposed. */

RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm));

mm->total_vm = oldmm->total_vm;

mm->shared_vm = oldmm->shared_vm;

mm->exec_vm = oldmm->exec_vm;

mm->stack_vm = oldmm->stack_vm;

rb_link = &mm->mm_rb.rb_node;

rb_parent = NULL;

pprev = &mm->mmap;

retval = ksm_fork(mm, oldmm);

if (retval)

goto out;

retval = khugepaged_fork(mm, oldmm);

if (retval)

goto out;

prev = NULL;

for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {

struct file *file;

if (mpnt->vm_flags & VM_DONTCOPY) {

vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,

-vma_pages(mpnt));

continue;

}

charge = 0;

if (mpnt->vm_flags & VM_ACCOUNT) {

unsigned long len = vma_pages(mpnt);

if (security_vm_enough_memory_mm(oldmm, len)) /* sic */

goto fail_nomem;

charge = len;

}

tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);

if (!tmp)

goto fail_nomem;

*tmp = *mpnt;

INIT_LIST_HEAD(&tmp->anon_vma_chain);

retval = vma_dup_policy(mpnt, tmp);

if (retval)

goto fail_nomem_policy;

tmp->vm_mm = mm;

if (anon_vma_fork(tmp, mpnt))

goto fail_nomem_anon_vma_fork;

tmp->vm_flags &= ~VM_LOCKED;

tmp->vm_next = tmp->vm_prev = NULL;

file = tmp->vm_file;

if (file) {

struct inode *inode = file_inode(file);

struct address_space *mapping = file->f_mapping;

get_file(file);

if (tmp->vm_flags & VM_DENYWRITE)

atomic_dec(&inode->i_writecount);

i_mmap_lock_write(mapping);

if (tmp->vm_flags & VM_SHARED)

atomic_inc(&mapping->i_mmap_writable);

flush_dcache_mmap_lock(mapping);

/* insert tmp into the share list, just after mpnt */

vma_interval_tree_insert_after(tmp, mpnt,

&mapping->i_mmap);

flush_dcache_mmap_unlock(mapping);

i_mmap_unlock_write(mapping);

}

/*

* 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);

/*

* Link in the new vma and copy the page table entries.

*/

*pprev = tmp;

pprev = &tmp->vm_next;

tmp->vm_prev = prev;

prev = tmp;

__vma_link_rb(mm, tmp, rb_link, rb_parent);

rb_link = &tmp->vm_rb.rb_right;

rb_parent = &tmp->vm_rb;

mm->map_count++;

retval = copy_page_range(mm, oldmm, mpnt);

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

tmp->vm_ops->open(tmp);

if (retval)

goto out;

}

/* a new mm has just been created */

arch_dup_mmap(oldmm, mm);

retval = 0;

out:

up_write(&mm->mmap_sem);

flush_tlb_mm(oldmm);

up_write(&oldmm->mmap_sem);

uprobe_end_dup_mmap();

return retval;

fail_nomem_anon_vma_fork:

mpol_put(vma_policy(tmp));

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)

{

pgd_free(mm, mm->pgd);

}

#else

static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)

{

down_write(&oldmm->mmap_sem);

RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm));

up_write(&oldmm->mmap_sem);

return 0;

}

#define mm_alloc_pgd(mm) (0)

#define mm_free_pgd(mm)

#endif /* CONFIG_MMU */

__cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);

#define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))

#define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))

static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;

static int __init coredump_filter_setup(char *s)

{

default_dump_filter =

(simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &

MMF_DUMP_FILTER_MASK;

return 1;

}

__setup("coredump_filter=", coredump_filter_setup);

#include <linux/init_task.h>

static void mm_init_aio(struct mm_struct *mm)

{

#ifdef CONFIG_AIO

spin_lock_init(&mm->ioctx_lock);

mm->ioctx_table = NULL;

#endif

}

static void mm_init_owner(struct mm_struct *mm, struct task_struct *p)

{

#ifdef CONFIG_MEMCG

mm->owner = p;

#endif

}

static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p)

{

mm->mmap = NULL;

mm->mm_rb = RB_ROOT;

mm->vmacache_seqnum = 0;

atomic_set(&mm->mm_users, 1);

atomic_set(&mm->mm_count, 1);

init_rwsem(&mm->mmap_sem);

INIT_LIST_HEAD(&mm->mmlist);

mm->core_state = NULL;

atomic_long_set(&mm->nr_ptes, 0);

mm_nr_pmds_init(mm);

mm->map_count = 0;

mm->locked_vm = 0;

mm->pinned_vm = 0;

memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));

spin_lock_init(&mm->page_table_lock);

mm_init_cpumask(mm);

mm_init_aio(mm);

mm_init_owner(mm, p);

mmu_notifier_mm_init(mm);

clear_tlb_flush_pending(mm);

#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS

mm->pmd_huge_pte = NULL;

#endif

if (current->mm) {

mm->flags = current->mm->flags & MMF_INIT_MASK;

mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK;

} else {

mm->flags = default_dump_filter;

mm->def_flags = 0;

}

if (mm_alloc_pgd(mm))

goto fail_nopgd;

if (init_new_context(p, mm))

goto fail_nocontext;

return mm;

fail_nocontext:

mm_free_pgd(mm);

fail_nopgd:

free_mm(mm);

return NULL;

}

static void check_mm(struct mm_struct *mm)

{

int i;

for (i = 0; i < NR_MM_COUNTERS; i++) {

long x = atomic_long_read(&mm->rss_stat.count[i]);

if (unlikely(x))

printk(KERN_ALERT "BUG: Bad rss-counter state "

"mm:%p idx:%d val:%ld\n", mm, i, x);

}

if (atomic_long_read(&mm->nr_ptes))

pr_alert("BUG: non-zero nr_ptes on freeing mm: %ld\n",

atomic_long_read(&mm->nr_ptes));

if (mm_nr_pmds(mm))

pr_alert("BUG: non-zero nr_pmds on freeing mm: %ld\n",

mm_nr_pmds(mm));

#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS

VM_BUG_ON_MM(mm->pmd_huge_pte, mm);

#endif

}

/*

* Allocate and initialize an mm_struct.

*/

struct mm_struct *mm_alloc(void)

{

struct mm_struct *mm;

mm = allocate_mm();

if (!mm)

return NULL;

memset(mm, 0, sizeof(*mm));

return mm_init(mm, current);

}

/*

* 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.

*/

void __mmdrop(struct mm_struct *mm)

{

BUG_ON(mm == &init_mm);

mm_free_pgd(mm);

destroy_context(mm);

mmu_notifier_mm_destroy(mm);

check_mm(mm);

free_mm(mm);

}

EXPORT_SYMBOL_GPL(__mmdrop);

/*

* Decrement the use count and release all resources for an mm.

*/

void mmput(struct mm_struct *mm)

{

might_sleep();

if (atomic_dec_and_test(&mm->mm_users)) {

uprobe_clear_state(mm);

exit_aio(mm);

ksm_exit(mm);

khugepaged_exit(mm); /* must run before exit_mmap */

exit_mmap(mm);

set_mm_exe_file(mm, NULL);

if (!list_empty(&mm->mmlist)) {

spin_lock(&mmlist_lock);

list_del(&mm->mmlist);

spin_unlock(&mmlist_lock);

}

if (mm->binfmt)

module_put(mm->binfmt->module);

mmdrop(mm);

}

}

EXPORT_SYMBOL_GPL(mmput);

/**

* set_mm_exe_file - change a reference to the mm's executable file

*

* This changes mm's executable file (shown as symlink /proc/[pid]/exe).

*

* Main users are mmput() and sys_execve(). Callers prevent concurrent

* invocations: in mmput() nobody alive left, in execve task is single

* threaded. sys_prctl(PR_SET_MM_MAP/EXE_FILE) also needs to set the

* mm->exe_file, but does so without using set_mm_exe_file() in order

* to do avoid the need for any locks.

*/

void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)

{

struct file *old_exe_file;

/*

* It is safe to dereference the exe_file without RCU as

* this function is only called if nobody else can access

* this mm -- see comment above for justification.

*/

old_exe_file = rcu_dereference_raw(mm->exe_file);

if (new_exe_file)

get_file(new_exe_file);

rcu_assign_pointer(mm->exe_file, new_exe_file);

if (old_exe_file)

fput(old_exe_file);

}

/**

* get_mm_exe_file - acquire a reference to the mm's executable file

*

* Returns %NULL if mm has no associated executable file.

* User must release file via fput().

*/

struct file *get_mm_exe_file(struct mm_struct *mm)

{

struct file *exe_file;

rcu_read_lock();

exe_file = rcu_dereference(mm->exe_file);

if (exe_file && !get_file_rcu(exe_file))

exe_file = NULL;

rcu_read_unlock();

return exe_file;

}

EXPORT_SYMBOL(get_mm_exe_file);

/**

* get_task_mm - acquire a reference to the task's mm

*

* Returns %NULL if the task has no mm. Checks PF_KTHREAD (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_KTHREAD)

mm = NULL;

else

atomic_inc(&mm->mm_users);

}

task_unlock(task);

return mm;

}

EXPORT_SYMBOL_GPL(get_task_mm);

struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)

{

struct mm_struct *mm;

int err;

err = mutex_lock_killable(&task->signal->cred_guard_mutex);

if (err)

return ERR_PTR(err);

mm = get_task_mm(task);

if (mm && mm != current->mm &&

!ptrace_may_access(task, mode)) {

mmput(mm);

mm = ERR_PTR(-EACCES);

}

mutex_unlock(&task->signal->cred_guard_mutex);

return mm;

}

static void complete_vfork_done(struct task_struct *tsk)

{

struct completion *vfork;

task_lock(tsk);

vfork = tsk->vfork_done;

if (likely(vfork)) {

tsk->vfork_done = NULL;

complete(vfork);

}

task_unlock(tsk);

}

static int wait_for_vfork_done(struct task_struct *child,

struct completion *vfork)

{

int killed;

freezer_do_not_count();

killed = wait_for_completion_killable(vfork);

freezer_count();

if (killed) {

task_lock(child);

child->vfork_done = NULL;

task_unlock(child);

}

put_task_struct(child);

return killed;

}

/* 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)

{

/* Get rid of any futexes when releasing the mm */

#ifdef CONFIG_FUTEX

if (unlikely(tsk->robust_list)) {

exit_robust_list(tsk);

tsk->robust_list = NULL;

}

#ifdef CONFIG_COMPAT

if (unlikely(tsk->compat_robust_list)) {

compat_exit_robust_list(tsk);

tsk->compat_robust_list = NULL;

}

#endif

if (unlikely(!list_empty(&tsk->pi_state_list)))

exit_pi_state_list(tsk);

#endif

uprobe_free_utask(tsk);

/* Get rid of any cached register state */

deactivate_mm(tsk, mm);

/*

* 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, say, a killed vfork parent shouldn't touch this mm.

* Userland only wants this done for a sys_exit.

*/

if (tsk->clear_child_tid) {

if (!(tsk->flags & PF_SIGNALED) &&

atomic_read(&mm->mm_users) > 1) {

/*

* We don't check the error code - if userspace has

* not set up a proper pointer then tough luck.

*/

put_user(0, tsk->clear_child_tid);

sys_futex(tsk->clear_child_tid, FUTEX_WAKE,

1, NULL, NULL, 0);

}

tsk->clear_child_tid = NULL;

}

/*

* All done, finally we can wake up parent and return this mm to him.

* Also kthread_stop() uses this completion for synchronization.

*/

if (tsk->vfork_done)

complete_vfork_done(tsk);

}

/*

* Allocate a new mm structure and copy contents from the

* mm structure of the passed in task structure.

*/

static struct mm_struct *dup_mm(struct task_struct *tsk)

{

struct mm_struct *mm, *oldmm = current->mm;

int err;

mm = allocate_mm();

if (!mm)

goto fail_nomem;

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

if (!mm_init(mm, tsk))

goto fail_nomem;

err = dup_mmap(mm, oldmm);

if (err)

goto free_pt;

mm->hiwater_rss = get_mm_rss(mm);

mm->hiwater_vm = mm->total_vm;

if (mm->binfmt && !try_module_get(mm->binfmt->module))

goto free_pt;

return mm;

free_pt:

/* don't put binfmt in mmput, we haven't got module yet */

mm->binfmt = NULL;

mmput(mm);

fail_nomem:

return NULL;

}

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;

#ifdef CONFIG_DETECT_HUNG_TASK

tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;

#endif

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;

/* initialize the new vmacache entries */

vmacache_flush(tsk);

if (clone_flags & CLONE_VM) {

atomic_inc(&oldmm->mm_users);

mm = oldmm;

goto good_mm;

}

retval = -ENOMEM;

mm = dup_mm(tsk);

if (!mm)

goto fail_nomem;

good_mm:

tsk->mm = mm;

tsk->active_mm = mm;

return 0;

fail_nomem:

return retval;

}

static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)

{

struct fs_struct *fs = current->fs;

if (clone_flags & CLONE_FS) {

/* tsk->fs is already what we want */

spin_lock(&fs->lock);

if (fs->in_exec) {

spin_unlock(&fs->lock);

return -EAGAIN;

}

fs->users++;