[PATCHv6 11/30] thp: handle file pages in mremap()

["Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>]

We need to mirror logic in move_ptes() wrt need_rmap_locks to get proper
serialization file THP.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 mm/mremap.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/mm/mremap.c b/mm/mremap.c
index 3fa0a467df66..88fa7ab1a8ce 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -192,17 +192,27 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
 			break;
 		if (pmd_trans_huge(*old_pmd)) {
 			if (extent == HPAGE_PMD_SIZE) {
+				struct address_space *mapping = NULL;
+				struct anon_vma *anon_vma = NULL;
 				bool moved;
-				VM_BUG_ON_VMA(vma->vm_file || !vma->anon_vma,
-					      vma);
 				/* See comment in move_ptes() */
-				if (need_rmap_locks)
-					anon_vma_lock_write(vma->anon_vma);
+				if (need_rmap_locks) {
+					if (vma->vm_file) {
+						mapping = vma->vm_file->f_mapping;
+						i_mmap_lock_write(mapping);
+					}
+					if (vma->anon_vma) {
+						anon_vma = vma->anon_vma;
+						anon_vma_lock_write(anon_vma);
+					}
+				}
 				moved = move_huge_pmd(vma, new_vma, old_addr,
 						    new_addr, old_end,
 						    old_pmd, new_pmd);
-				if (need_rmap_locks)
-					anon_vma_unlock_write(vma->anon_vma);
+				if (anon_vma)
+					anon_vma_unlock_write(anon_vma);
+				if (mapping)
+					i_mmap_unlock_write(mapping);
 				if (moved) {
 					need_flush = true;
 					continue;
-- 
2.8.0.rc3

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