mm/gup: finish consolidating error handling

Commit df06b37ffe5a ("mm/gup: cache dev_pagemap while pinning pages")
attempted to operate on each page that get_user_pages had retrieved.  In
order to do that, it created a common exit point from the routine.
However, one case was missed, which this patch fixes up.

Also, there was still an unnecessary shadow declaration (with a
different type) of the "ret" variable, which this patch removes.

Keith's description of the situation is:

  This also fixes a potentially leaked dev_pagemap reference count if a
  failure occurs when an iteration crosses a vma boundary.  I don't think
  it's normal to have different vma's on a users mapped zone device
  memory, but good to fix anyway.

I actually thought that this code:

    /* first iteration or cross vma bound */
    if (!vma || start >= vma->vm_end) {
	        vma = find_extend_vma(mm, start);
	        if (!vma && in_gate_area(mm, start)) {
		            ret = get_gate_page(mm, start & PAGE_MASK,
		                    gup_flags, &vma,
		                    pages ? &pages[i] : NULL);
		            if (ret)
		                goto out;

dealt with the "you're trying to pin the gate page, as part of this
call", rather than the generic case of crossing a vma boundary.  (I
think there's a fine point that I must be overlooking.) But it's still a
valid case, either way.

Fixes: df06b37ffe5a4 ("mm/gup: cache dev_pagemap while pinning pages")
Signed-off-by: John Hubbard <>
Reviewed-by: Keith Busch <>
Cc: Dan Williams <>
Cc: Kirill A. Shutemov <>
Cc: Dave Hansen <>
Signed-off-by: Andrew Morton <>
Signed-off-by: Linus Torvalds <>
1 file changed