Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 1274 insertions, 0 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
new file mode 100644
index 00000000000..f42a17f8869
--- /dev/null
+++ b/kernel/fork.c
@@ -0,0 +1,1274 @@
+/*
+ *  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/config.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/unistd.h>
+#include <linux/smp_lock.h>
+#include <linux/module.h>
+#include <linux/vmalloc.h>
+#include <linux/completion.h>
+#include <linux/namespace.h>
+#include <linux/personality.h>
+#include <linux/mempolicy.h>
+#include <linux/sem.h>
+#include <linux/file.h>
+#include <linux/key.h>
+#include <linux/binfmts.h>
+#include <linux/mman.h>
+#include <linux/fs.h>
+#include <linux/cpu.h>
+#include <linux/cpuset.h>
+#include <linux/security.h>
+#include <linux/swap.h>
+#include <linux/syscalls.h>
+#include <linux/jiffies.h>
+#include <linux/futex.h>
+#include <linux/ptrace.h>
+#include <linux/mount.h>
+#include <linux/audit.h>
+#include <linux/profile.h>
+#include <linux/rmap.h>
+#include <linux/acct.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>
+
+/*
+ * 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 */
+
+EXPORT_SYMBOL(tasklist_lock);
+
+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))
+static kmem_cache_t *task_struct_cachep;
+#endif
+
+/* SLAB cache for signal_struct structures (tsk->signal) */
+kmem_cache_t *signal_cachep;
+
+/* SLAB cache for sighand_struct structures (tsk->sighand) */
+kmem_cache_t *sighand_cachep;
+
+/* SLAB cache for files_struct structures (tsk->files) */
+kmem_cache_t *files_cachep;
+
+/* SLAB cache for fs_struct structures (tsk->fs) */
+kmem_cache_t *fs_cachep;
+
+/* SLAB cache for vm_area_struct structures */
+kmem_cache_t *vm_area_cachep;
+
+/* SLAB cache for mm_struct structures (tsk->mm) */
+static kmem_cache_t *mm_cachep;
+
+void free_task(struct task_struct *tsk)
+{
+	free_thread_info(tsk->thread_info);
+	free_task_struct(tsk);
+}
+EXPORT_SYMBOL(free_task);
+
+void __put_task_struct(struct task_struct *tsk)
+{
+	WARN_ON(!(tsk->exit_state & (EXIT_DEAD | EXIT_ZOMBIE)));
+	WARN_ON(atomic_read(&tsk->usage));
+	WARN_ON(tsk == current);
+
+	if (unlikely(tsk->audit_context))
+		audit_free(tsk);
+	security_task_free(tsk);
+	free_uid(tsk->user);
+	put_group_info(tsk->group_info);
+
+	if (!profile_handoff_task(tsk))
+		free_task(tsk);
+}
+
+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),
+			ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL, NULL);
+#endif
+
+	/*
+	 * 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];
+}
+
+static struct task_struct *dup_task_struct(struct task_struct *orig)
+{
+	struct task_struct *tsk;
+	struct thread_info *ti;
+
+	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;
+	}
+
+	*ti = *orig->thread_info;
+	*tsk = *orig;
+	tsk->thread_info = ti;
+	ti->task = tsk;
+
+	/* One for us, one for whoever does the "release_task()" (usually parent) */
+	atomic_set(&tsk->usage,2);
+	return tsk;
+}
+
+#ifdef CONFIG_MMU
+static inline int dup_mmap(struct mm_struct * mm, struct mm_struct * oldmm)
+{
+	struct vm_area_struct * mpnt, *tmp, **pprev;
+	struct rb_node **rb_link, *rb_parent;
+	int retval;
+	unsigned long charge;
+	struct mempolicy *pol;
+
+	down_write(&oldmm->mmap_sem);
+	flush_cache_mm(current->mm);
+	mm->locked_vm = 0;
+	mm->mmap = NULL;
+	mm->mmap_cache = NULL;
+	mm->free_area_cache = oldmm->mmap_base;
+	mm->map_count = 0;
+	set_mm_counter(mm, rss, 0);
+	set_mm_counter(mm, anon_rss, 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;
+
+	for (mpnt = current->mm->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 int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
+			if (security_vm_enough_memory(len))
+				goto fail_nomem;
+			charge = len;
+		}
+		tmp = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
+		if (!tmp)
+			goto fail_nomem;
+		*tmp = *mpnt;
+		pol = mpol_copy(vma_policy(mpnt));
+		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) {
+			struct inode *inode = file->f_dentry->d_inode;
+			get_file(file);
+			if (tmp->vm_flags & VM_DENYWRITE)
+				atomic_dec(&inode->i_writecount);
+      
+			/* 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);
+		}
+
+		/*
+		 * Link in the new vma and copy the page table entries:
+		 * link in first so that swapoff can see swap entries,
+		 * and try_to_unmap_one's find_vma find the new vma.
+		 */
+		spin_lock(&mm->page_table_lock);
+		*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++;
+		retval = copy_page_range(mm, current->mm, tmp);
+		spin_unlock(&mm->page_table_lock);
+
+		if (tmp->vm_ops && tmp->vm_ops->open)
+			tmp->vm_ops->open(tmp);
+
+		if (retval)
+			goto out;
+	}
+	retval = 0;
+
+out:
+	flush_tlb_mm(current->mm);
+	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)
+{
+	pgd_free(mm->pgd);
+}
+#else
+#define dup_mmap(mm, oldmm)	(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, SLAB_KERNEL))
+#define free_mm(mm)	(kmem_cache_free(mm_cachep, (mm)))
+
+#include <linux/init_task.h>
+
+static struct mm_struct * mm_init(struct mm_struct * mm)
+{
+	atomic_set(&mm->mm_users, 1);
+	atomic_set(&mm->mm_count, 1);
+	init_rwsem(&mm->mmap_sem);
+	INIT_LIST_HEAD(&mm->mmlist);
+	mm->core_waiters = 0;
+	mm->nr_ptes = 0;
+	spin_lock_init(&mm->page_table_lock);
+	rwlock_init(&mm->ioctx_list_lock);
+	mm->ioctx_list = NULL;
+	mm->default_kioctx = (struct kioctx)INIT_KIOCTX(mm->default_kioctx, *mm);
+	mm->free_area_cache = TASK_UNMAPPED_BASE;
+
+	if (likely(!mm_alloc_pgd(mm))) {
+		mm->def_flags = 0;
+		return mm;
+	}
+	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));
+		mm = mm_init(mm);
+	}
+	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.
+ */
+void fastcall __mmdrop(struct mm_struct *mm)
+{
+	BUG_ON(mm == &init_mm);
+	mm_free_pgd(mm);
+	destroy_context(mm);
+	free_mm(mm);
+}
+
+/*
+ * Decrement the use count and release all resources for an mm.
+ */
+void mmput(struct mm_struct *mm)
+{
+	if (atomic_dec_and_test(&mm->mm_users)) {
+		exit_aio(mm);
+		exit_mmap(mm);
+		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);
+	}
+	if (tsk->clear_child_tid && atomic_read(&mm->mm_users) > 1) {
+		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);
+	}
+}
+
+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;
+		/*
+		 * There are cases where the PTL is held to ensure no
+		 * new threads start up in user mode using an mm, which
+		 * allows optimizing out ipis; the tlb_gather_mmu code
+		 * is an example.
+		 */
+		spin_unlock_wait(&oldmm->page_table_lock);
+		goto good_mm;
+	}
+
+	retval = -ENOMEM;
+	mm = allocate_mm();
+	if (!mm)
+		goto fail_nomem;
+
+	/* Copy the current MM stuff.. */
+	memcpy(mm, oldmm, sizeof(*mm));
+	if (!mm_init(mm))
+		goto fail_nomem;
+
+	if (init_new_context(tsk,mm))
+		goto fail_nocontext;
+
+	retval = dup_mmap(mm, oldmm);
+	if (retval)
+		goto free_pt;
+
+	mm->hiwater_rss = get_mm_counter(mm,rss);
+	mm->hiwater_vm = mm->total_vm;
+
+good_mm:
+	tsk->mm = mm;
+	tsk->active_mm = mm;
+	return 0;
+
+free_pt:
+	mmput(mm);
+fail_nomem:
+	return retval;
+
+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 retval;
+}
+
+static inline struct fs_struct *__copy_fs_struct(struct fs_struct *old)
+{
+	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);
+		fs->rootmnt = mntget(old->rootmnt);
+		fs->root = dget(old->root);
+		fs->pwdmnt = mntget(old->pwdmnt);
+		fs->pwd = dget(old->pwd);
+		if (old->altroot) {
+			fs->altrootmnt = mntget(old->altrootmnt);
+			fs->altroot = dget(old->altroot);
+		} else {
+			fs->altrootmnt = NULL;
+			fs->altroot = NULL;
+		}
+		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);
+
+static inline int copy_fs(unsigned long clone_flags, struct task_struct * tsk)
+{
+	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;
+}
+
+static int count_open_files(struct files_struct *files, int size)
+{
+	int i;
+
+	/* Find the last open fd */
+	for (i = size/(8*sizeof(long)); i > 0; ) {
+		if (files->open_fds->fds_bits[--i])
+			break;
+	}
+	i = (i+1) * 8 * sizeof(long);
+	return i;
+}
+
+static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
+{
+	struct files_struct *oldf, *newf;
+	struct file **old_fds, **new_fds;
+	int open_files, size, i, error = 0, expand;
+
+	/*
+	 * 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;
+	}
+
+	/*
+	 * Note: we may be using current for both targets (See exec.c)
+	 * This works because we cache current->files (old) as oldf. Don't
+	 * break this.
+	 */
+	tsk->files = NULL;
+	error = -ENOMEM;
+	newf = kmem_cache_alloc(files_cachep, SLAB_KERNEL);
+	if (!newf) 
+		goto out;
+
+	atomic_set(&newf->count, 1);
+
+	spin_lock_init(&newf->file_lock);
+	newf->next_fd	    = 0;
+	newf->max_fds	    = NR_OPEN_DEFAULT;
+	newf->max_fdset	    = __FD_SETSIZE;
+	newf->close_on_exec = &newf->close_on_exec_init;
+	newf->open_fds	    = &newf->open_fds_init;
+	newf->fd	    = &newf->fd_array[0];
+
+	spin_lock(&oldf->file_lock);
+
+	open_files = count_open_files(oldf, oldf->max_fdset);
+	expand = 0;
+
+	/*
+	 * Check whether we need to allocate a larger fd array or fd set.
+	 * Note: we're not a clone task, so the open count won't  change.
+	 */
+	if (open_files > newf->max_fdset) {
+		newf->max_fdset = 0;
+		expand = 1;
+	}
+	if (open_files > newf->max_fds) {
+		newf->max_fds = 0;
+		expand = 1;
+	}
+
+	/* if the old fdset gets grown now, we'll only copy up to "size" fds */
+	if (expand) {
+		spin_unlock(&oldf->file_lock);
+		spin_lock(&newf->file_lock);
+		error = expand_files(newf, open_files-1);
+		spin_unlock(&newf->file_lock);
+		if (error < 0)
+			goto out_release;
+		spin_lock(&oldf->file_lock);
+	}
+
+	old_fds = oldf->fd;
+	new_fds = newf->fd;
+
+	memcpy(newf->open_fds->fds_bits, oldf->open_fds->fds_bits, open_files/8);
+	memcpy(newf->close_on_exec->fds_bits, oldf->close_on_exec->fds_bits, open_files/8);
+
+	for (i = open_files; i != 0; i--) {
+		struct file *f = *old_fds++;
+		if (f) {
+			get_file(f);
+		} else {
+			/*
+			 * The fd may be claimed in the fd bitmap but not yet
+			 * instantiated in the files array if a sibling thread
+			 * is partway through open().  So make sure that this
+			 * fd is available to the new process.
+			 */
+			FD_CLR(open_files - i, newf->open_fds);
+		}
+		*new_fds++ = f;
+	}
+	spin_unlock(&oldf->file_lock);
+
+	/* compute the remainder to be cleared */
+	size = (newf->max_fds - open_files) * sizeof(struct file *);
+
+	/* This is long word aligned thus could use a optimized version */ 
+	memset(new_fds, 0, size); 
+
+	if (newf->max_fdset > open_files) {
+		int left = (newf->max_fdset-open_files)/8;
+		int start = open_files / (8 * sizeof(unsigned long));
+
+		memset(&newf->open_fds->fds_bits[start], 0, left);
+		memset(&newf->close_on_exec->fds_bits[start], 0, left);
+	}
+
+	tsk->files = newf;
+	error = 0;
+out:
+	return error;
+
+out_release:
+	free_fdset (newf->close_on_exec, newf->max_fdset);
+	free_fdset (newf->open_fds, newf->max_fdset);
+	free_fd_array(newf->fd, newf->max_fds);
+	kmem_cache_free(files_cachep, newf);
+	goto out;
+}
+
+/*
+ *	Helper to unshare the files of the current task.
+ *	We don't want to expose copy_files internals to
+ *	the exec layer of the kernel.
+ */
+
+int unshare_files(void)
+{
+	struct files_struct *files  = current->files;
+	int rc;
+
+	if(!files)
+		BUG();
+
+	/* This can race but the race causes us to copy when we don't
+	   need to and drop the copy */
+	if(atomic_read(&files->count) == 1)
+	{
+		atomic_inc(&files->count);
+		return 0;
+	}
+	rc = copy_files(0, current);
+	if(rc)
+		current->files = files;
+	return rc;
+}
+
+EXPORT_SYMBOL(unshare_files);
+
+static inline int copy_sighand(unsigned long clone_flags, struct task_struct * tsk)
+{
+	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);
+	tsk->sighand = sig;
+	if (!sig)
+		return -ENOMEM;
+	spin_lock_init(&sig->siglock);
+	atomic_set(&sig->count, 1);
+	memcpy(sig->action, current->sighand->action, sizeof(sig->action));
+	return 0;
+}
+
+static inline int copy_signal(unsigned long clone_flags, struct task_struct * tsk)
+{
+	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;
+	sig->curr_target = NULL;
+	init_sigpending(&sig->shared_pending);
+	INIT_LIST_HEAD(&sig->posix_timers);
+
+	sig->it_real_value = sig->it_real_incr = 0;
+	sig->real_timer.function = it_real_fn;
+	sig->real_timer.data = (unsigned long) tsk;
+	init_timer(&sig->real_timer);
+
+	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->tty = current->signal->tty;
+	sig->pgrp = process_group(current);
+	sig->session = current->signal->session;
+	sig->leader = 0;	/* session leadership doesn't inherit */
+	sig->tty_old_pgrp = 0;
+
+	sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero;
+	sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0;
+	sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0;
+	sig->sched_time = 0;
+	INIT_LIST_HEAD(&sig->cpu_timers[0]);
+	INIT_LIST_HEAD(&sig->cpu_timers[1]);
+	INIT_LIST_HEAD(&sig->cpu_timers[2]);
+
+	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);
+	}
+
+	return 0;
+}
+
+static inline void copy_flags(unsigned long clone_flags, struct task_struct *p)
+{
+	unsigned long new_flags = p->flags;
+
+	new_flags &= ~PF_SUPERPRIV;
+	new_flags |= PF_FORKNOEXEC;
+	if (!(clone_flags & CLONE_PTRACE))
+		p->ptrace = 0;
+	p->flags = new_flags;
+}
+
+asmlinkage long sys_set_tid_address(int __user *tidptr)
+{
+	current->clear_child_tid = tidptr;
+
+	return current->pid;
+}
+
+/*
+ * 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.
+ */
+static task_t *copy_process(unsigned long clone_flags,
+				 unsigned long stack_start,
+				 struct pt_regs *regs,
+				 unsigned long stack_size,
+				 int __user *parent_tidptr,
+				 int __user *child_tidptr,
+				 int pid)
+{
+	int retval;
+	struct task_struct *p = NULL;
+
+	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;
+
+	retval = -EAGAIN;
+	if (atomic_read(&p->user->processes) >=
+			p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
+		if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
+				p->user != &root_user)
+			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;
+
+	if (!try_module_get(p->thread_info->exec_domain->module))
+		goto bad_fork_cleanup_count;
+
+	if (p->binfmt && !try_module_get(p->binfmt->module))
+		goto bad_fork_cleanup_put_domain;
+
+	p->did_exec = 0;
+	copy_flags(clone_flags, p);
+	p->pid = pid;
+	retval = -EFAULT;
+	if (clone_flags & CLONE_PARENT_SETTID)
+		if (put_user(p->pid, parent_tidptr))
+			goto bad_fork_cleanup;
+
+	p->proc_dentry = NULL;
+
+	INIT_LIST_HEAD(&p->children);
+	INIT_LIST_HEAD(&p->sibling);
+	p->vfork_done = NULL;
+	spin_lock_init(&p->alloc_lock);
+	spin_lock_init(&p->proc_lock);
+
+	clear_tsk_thread_flag(p, TIF_SIGPENDING);
+	init_sigpending(&p->pending);
+
+	p->utime = cputime_zero;
+	p->stime = cputime_zero;
+ 	p->sched_time = 0;
+	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 */
+	acct_clear_integrals(p);
+
+ 	p->it_virt_expires = cputime_zero;
+	p->it_prof_expires = cputime_zero;
+ 	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]);
+
+	p->lock_depth = -1;		/* -1 = no lock */
+	do_posix_clock_monotonic_gettime(&p->start_time);
+	p->security = NULL;
+	p->io_context = NULL;
+	p->io_wait = NULL;
+	p->audit_context = NULL;
+#ifdef CONFIG_NUMA
+ 	p->mempolicy = mpol_copy(p->mempolicy);
+ 	if (IS_ERR(p->mempolicy)) {
+ 		retval = PTR_ERR(p->mempolicy);
+ 		p->mempolicy = NULL;
+ 		goto bad_fork_cleanup;
+ 	}
+#endif
+
+	p->tgid = p->pid;
+	if (clone_flags & CLONE_THREAD)
+		p->tgid = current->tgid;
+
+	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;
+	if ((retval = copy_namespace(clone_flags, p)))
+		goto bad_fork_cleanup_keys;
+	retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
+	if (retval)
+		goto bad_fork_cleanup_namespace;
+
+	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;
+
+	/*
+	 * Syscall tracing should be turned off in the child regardless
+	 * of CLONE_PTRACE.
+	 */
+	clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
+
+	/* 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;
+
+	/* Perform scheduler related setup */
+	sched_fork(p);
+
+	/*
+	 * Ok, make it visible to the rest of the system.
+	 * We dont wake it up yet.
+	 */
+	p->group_leader = p;
+	INIT_LIST_HEAD(&p->ptrace_children);
+	INIT_LIST_HEAD(&p->ptrace_list);
+
+	/* Need tasklist lock for parent etc handling! */
+	write_lock_irq(&tasklist_lock);
+
+	/*
+	 * The task hasn't been attached yet, so cpus_allowed mask cannot
+	 * have changed. The cpus_allowed mask of the parent may have
+	 * changed after it was copied first time, and it may then move to
+	 * another CPU - so we re-copy it here and set the child's CPU to
+	 * the parent's CPU. This avoids alot of nasty races.
+	 */
+	p->cpus_allowed = current->cpus_allowed;
+	set_task_cpu(p, smp_processor_id());
+
+	/*
+	 * Check for pending SIGKILL! The new thread should not be allowed
+	 * to slip out of an OOM kill. (or normal SIGKILL.)
+	 */
+	if (sigismember(&current->pending.signal, SIGKILL)) {
+		write_unlock_irq(&tasklist_lock);
+		retval = -EINTR;
+		goto bad_fork_cleanup_namespace;
+	}
+
+	/* 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;
+
+	if (clone_flags & CLONE_THREAD) {
+		spin_lock(&current->sighand->siglock);
+		/*
+		 * Important: if an exit-all has been started then
+		 * do not create this new thread - the whole thread
+		 * group is supposed to exit anyway.
+		 */
+		if (current->signal->flags & SIGNAL_GROUP_EXIT) {
+			spin_unlock(&current->sighand->siglock);
+			write_unlock_irq(&tasklist_lock);
+			retval = -EAGAIN;
+			goto bad_fork_cleanup_namespace;
+		}
+		p->group_leader = current->group_leader;
+
+		if (current->signal->group_stop_count > 0) {
+			/*
+			 * There is an all-stop in progress for the group.
+			 * We ourselves will stop as soon as we check signals.
+			 * Make the new thread part of that group stop too.
+			 */
+			current->signal->group_stop_count++;
+			set_tsk_thread_flag(p, TIF_SIGPENDING);
+		}
+
+		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);
+		}
+
+		spin_unlock(&current->sighand->siglock);
+	}
+
+	SET_LINKS(p);
+	if (unlikely(p->ptrace & PT_PTRACED))
+		__ptrace_link(p, current->parent);
+
+	cpuset_fork(p);
+
+	attach_pid(p, PIDTYPE_PID, p->pid);
+	attach_pid(p, PIDTYPE_TGID, p->tgid);
+	if (thread_group_leader(p)) {
+		attach_pid(p, PIDTYPE_PGID, process_group(p));
+		attach_pid(p, PIDTYPE_SID, p->signal->session);
+		if (p->pid)
+			__get_cpu_var(process_counts)++;
+	}
+
+	nr_threads++;
+	total_forks++;
+	write_unlock_irq(&tasklist_lock);
+	retval = 0;
+
+fork_out:
+	if (retval)
+		return ERR_PTR(retval);
+	return p;
+
+bad_fork_cleanup_namespace:
+	exit_namespace(p);
+bad_fork_cleanup_keys:
+	exit_keys(p);
+bad_fork_cleanup_mm:
+	if (p->mm)
+		mmput(p->mm);
+bad_fork_cleanup_signal:
+	exit_signal(p);
+bad_fork_cleanup_sighand:
+	exit_sighand(p);
+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
+	mpol_free(p->mempolicy);
+#endif
+bad_fork_cleanup:
+	if (p->binfmt)
+		module_put(p->binfmt->module);
+bad_fork_cleanup_put_domain:
+	module_put(p->thread_info->exec_domain->module);
+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);
+	goto fork_out;
+}
+
+struct pt_regs * __devinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
+{
+	memset(regs, 0, sizeof(struct pt_regs));
+	return regs;
+}
+
+task_t * __devinit fork_idle(int cpu)
+{
+	task_t *task;
+	struct pt_regs regs;
+
+	task = copy_process(CLONE_VM, 0, idle_regs(&regs), 0, NULL, NULL, 0);
+	if (!task)
+		return ERR_PTR(-ENOMEM);
+	init_idle(task, cpu);
+	unhash_process(task);
+	return task;
+}
+
+static inline int fork_traceflag (unsigned clone_flags)
+{
+	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;
+	long pid = alloc_pidmap();
+
+	if (pid < 0)
+		return -EAGAIN;
+	if (unlikely(current->ptrace)) {
+		trace = fork_traceflag (clone_flags);
+		if (trace)
+			clone_flags |= CLONE_PTRACE;
+	}
+
+	p = copy_process(clone_flags, stack_start, regs, stack_size, parent_tidptr, child_tidptr, pid);
+	/*
+	 * 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;
+
+		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
+			p->state = TASK_STOPPED;
+
+		if (unlikely (trace)) {
+			current->ptrace_message = pid;
+			ptrace_notify ((trace << 8) | SIGTRAP);
+		}
+
+		if (clone_flags & CLONE_VFORK) {
+			wait_for_completion(&vfork);
+			if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE))
+				ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP);
+		}
+	} else {
+		free_pidmap(pid);
+		pid = PTR_ERR(p);
+	}
+	return pid;
+}
+
+void __init proc_caches_init(void)
+{
+	sighand_cachep = kmem_cache_create("sighand_cache",
+			sizeof(struct sighand_struct), 0,
+			SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
+	signal_cachep = kmem_cache_create("signal_cache",
+			sizeof(struct signal_struct), 0,
+			SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
+	files_cachep = kmem_cache_create("files_cache", 
+			sizeof(struct files_struct), 0,
+			SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
+	fs_cachep = kmem_cache_create("fs_cache", 
+			sizeof(struct fs_struct), 0,
+			SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
+	vm_area_cachep = kmem_cache_create("vm_area_struct",
+			sizeof(struct vm_area_struct), 0,
+			SLAB_PANIC, NULL, NULL);
+	mm_cachep = kmem_cache_create("mm_struct",
+			sizeof(struct mm_struct), 0,
+			SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
+}