mm: make the vma list be doubly linked

[net-next-2.6.git] / kernel / fork.c

diff --git a/kernel/fork.c b/kernel/fork.c
index 98b450876f93878b437bbbc6efe6abd1c4028b29..b7e9d60a675d3a08a1096ce725380229217d9fa3 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -300,7 +300,7 @@ out:
 #ifdef CONFIG_MMU
 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
 {
-       struct vm_area_struct *mpnt, *tmp, **pprev;
+       struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
        struct rb_node **rb_link, *rb_parent;
        int retval;
        unsigned long charge;
@@ -328,6 +328,7 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
        if (retval)
                goto out;
 
+       prev = NULL;
        for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
                struct file *file;
 
@@ -359,7 +360,7 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
                        goto fail_nomem_anon_vma_fork;
                tmp->vm_flags &= ~VM_LOCKED;
                tmp->vm_mm = mm;
-               tmp->vm_next = NULL;
+               tmp->vm_next = tmp->vm_prev = NULL;
                file = tmp->vm_file;
                if (file) {
                        struct inode *inode = file->f_path.dentry->d_inode;
@@ -392,6 +393,8 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
                 */
                *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;
@@ -752,13 +755,13 @@ 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 */
-               write_lock(&fs->lock);
+               spin_lock(&fs->lock);
                if (fs->in_exec) {
-                       write_unlock(&fs->lock);
+                       spin_unlock(&fs->lock);
                        return -EAGAIN;
                }
                fs->users++;
-               write_unlock(&fs->lock);
+               spin_unlock(&fs->lock);
                return 0;
        }
        tsk->fs = copy_fs_struct(fs);
@@ -1676,13 +1679,13 @@ SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
 
                if (new_fs) {
                        fs = current->fs;
-                       write_lock(&fs->lock);
+                       spin_lock(&fs->lock);
                        current->fs = new_fs;
                        if (--fs->users)
                                new_fs = NULL;
                        else
                                new_fs = fs;
-                       write_unlock(&fs->lock);
+                       spin_unlock(&fs->lock);
                }
 
                if (new_mm) {