thp: run vma_adjust_trans_huge() outside i_mmap_rwsem

vma_addjust_trans_huge() splits pmd if it's crossing VMA boundary.
During split we munlock the huge page which requires rmap walk.  rmap
wants to take the lock on its own.

Let's move vma_adjust_trans_huge() outside i_mmap_rwsem to fix this.

Link: http://lkml.kernel.org/r/1466021202-61880-19-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/mmap.c b/mm/mmap.c
index 234edffec1d0791251c631fc596b798dc49b7c91..31f9b2220b723e27dc9976650afeb7dc6141a2d2 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -675,6 +675,8 @@ again:                      remove_next = 1 + (end > next->vm_end);
                }
        }
 
+       vma_adjust_trans_huge(vma, start, end, adjust_next);
+
        if (file) {
                mapping = file->f_mapping;
                root = &mapping->i_mmap;
@@ -695,8 +697,6 @@ again:                      remove_next = 1 + (end > next->vm_end);
                }
        }
 
-       vma_adjust_trans_huge(vma, start, end, adjust_next);
-
        anon_vma = vma->anon_vma;
        if (!anon_vma && adjust_next)
                anon_vma = next->anon_vma;