2 files changed, 13 insertions, 3 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 6abcd0b72ae0..1d1838de6882 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -478,6 +478,16 @@ static inline void i_mmap_unlock_write(struct address_space *mapping)
         up_write(&mapping->i_mmap_rwsem);
 }
 
+static inline void i_mmap_lock_read(struct address_space *mapping)
+{
+        down_read(&mapping->i_mmap_rwsem);
+}
+
+static inline void i_mmap_unlock_read(struct address_space *mapping)
+{
+        up_read(&mapping->i_mmap_rwsem);
+}
+
 /*
  * Might pages of this file be mapped into userspace?
  */
diff --git a/mm/rmap.c b/mm/rmap.c
index 18247f89f1a8..14ad2b3b0f54 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1690,7 +1690,8 @@ static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc)
 
         if (!mapping)
                 return ret;
-        i_mmap_lock_write(mapping);
+
+        i_mmap_lock_read(mapping);
         vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
                 unsigned long address = vma_address(page, vma);
 
@@ -1711,9 +1712,8 @@ static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc)
                 goto done;
 
         ret = rwc->file_nonlinear(page, mapping, rwc->arg);
-
 done:
-        i_mmap_unlock_write(mapping);
+        i_mmap_unlock_read(mapping);
         return ret;
 }