Merge branches 'x86/acpi', 'x86/asm', 'x86/cpudetect', 'x86/crashdump', 'x86/debug...

[linux-2.6-omap-h63xx.git] / mm / mlock.c

diff --git a/mm/mlock.c b/mm/mlock.c
index 2904a347e4761169655696120751c371e4d74959..037161d61b4e72432d9d6bae71507d251b522afc 100644 (file)
--- 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 +310,11 @@ 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;
+               __mlock_vma_pages_range(vma, start, end, 1);
 
-               return 0;       /* hide other errors from mmap(), et al */
+               /* Hide errors from mmap() and other callers */
+               return 0;
        }
 
        /*
@@ -438,41 +425,14 @@ 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);
        }