1 files changed, 2 insertions, 45 deletions

diff --git a/mm/mlock.c b/mm/mlock.c
index 2904a347e476..028ec482fdd4 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -294,14 +294,10 @@ static inline int __mlock_posix_error_return(long retval)
  *
  * return number of pages [> 0] to be removed from locked_vm on success
  * of "special" vmas.
- *
- * return negative error if vma spanning @start-@range disappears while
- * mmap semaphore is dropped.  Unlikely?
  */
 long mlock_vma_pages_range(struct vm_area_struct *vma,
                         unsigned long start, unsigned long end)
 {
-        struct mm_struct *mm = vma->vm_mm;
         int nr_pages = (end - start) / PAGE_SIZE;
         BUG_ON(!(vma->vm_flags & VM_LOCKED));
 
@@ -314,20 +310,8 @@ long mlock_vma_pages_range(struct vm_area_struct *vma,
         if (!((vma->vm_flags & (VM_DONTEXPAND | VM_RESERVED)) ||
                         is_vm_hugetlb_page(vma) ||
                         vma == get_gate_vma(current))) {
-                long error;
-                downgrade_write(&mm->mmap_sem);
-
-                error = __mlock_vma_pages_range(vma, start, end, 1);
 
-                up_read(&mm->mmap_sem);
-                /* vma can change or disappear */
-                down_write(&mm->mmap_sem);
-                vma = find_vma(mm, start);
-                /* non-NULL vma must contain @start, but need to check @end */
-                if (!vma ||  end > vma->vm_end)
-                        return -ENOMEM;
-
-                return 0;       /* hide other errors from mmap(), et al */
+                return __mlock_vma_pages_range(vma, start, end, 1);
         }
 
         /*
@@ -438,41 +422,14 @@ success:
         vma->vm_flags = newflags;
 
         if (lock) {
-                /*
-                 * mmap_sem is currently held for write.  Downgrade the write
-                 * lock to a read lock so that other faults, mmap scans, ...
-                 * while we fault in all pages.
-                 */
-                downgrade_write(&mm->mmap_sem);
-
                 ret = __mlock_vma_pages_range(vma, start, end, 1);
 
-                /*
-                 * Need to reacquire mmap sem in write mode, as our callers
-                 * expect this.  We have no support for atomically upgrading
-                 * a sem to write, so we need to check for ranges while sem
-                 * is unlocked.
-                 */
-                up_read(&mm->mmap_sem);
-                /* vma can change or disappear */
-                down_write(&mm->mmap_sem);
-                *prev = find_vma(mm, start);
-                /* non-NULL *prev must contain @start, but need to check @end */
-                if (!(*prev) || end > (*prev)->vm_end)
-                        ret = -ENOMEM;
-                else if (ret > 0) {
+                if (ret > 0) {
                         mm->locked_vm -= ret;
                         ret = 0;
                 } else
                         ret = __mlock_posix_error_return(ret); /* translate if needed */
         } else {
-                /*
-                 * TODO:  for unlocking, pages will already be resident, so
-                 * we don't need to wait for allocations/reclaim/pagein, ...
-                 * However, unlocking a very large region can still take a
-                 * while.  Should we downgrade the semaphore for both lock
-                 * AND unlock ?
-                 */
                 __mlock_vma_pages_range(vma, start, end, 0);
         }