1 files changed, 10 insertions, 7 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index 98b450876f9..b7e9d60a675 100644
--- 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) {