[PATCHv8 13/32] thp: run vma_adjust_trans_huge() outside i_mmap_rwsem

Kirill A. Shutemov
2016-05-12T15:41:56Z

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.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
mm/mmap.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index bd2e1a533bc1..df3976af9302 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -678,6 +678,8 @@ 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;
@@ -698,8 +700,6 @@ 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;
--
2.8.1