[PATCH] hugetlbfs: check dir in trace_hugetlbfs_alloc_inode

[zhuxiaohui]

From: Xiaohui Zhu <zhuxiaohui.400@xxxxxxxxxxxxx>

Anonymous huge page has no corresponding directory inode,
which cause a null pointer crash when access dir with the stack

  trace_hugetlbfs_alloc_inode
  hugetlbfs_get_inode
  hugetlb_file_setup
  ksys_mmap_pgoff

Signed-off-by: Xiaohui Zhu <zhuxiaohui.400@xxxxxxxxxxxxx>
---
 include/trace/events/hugetlbfs.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/trace/events/hugetlbfs.h b/include/trace/events/hugetlbfs.h
index 8331c904a9ba..5daa52053edc 100644
--- a/include/trace/events/hugetlbfs.h
+++ b/include/trace/events/hugetlbfs.h
@@ -23,7 +23,9 @@ TRACE_EVENT(hugetlbfs_alloc_inode,
 	TP_fast_assign(
 		__entry->dev		= inode->i_sb->s_dev;
 		__entry->ino		= inode->i_ino;
-		__entry->dir		= dir->i_ino;
+		__entry->dir		= 0;
+		if (dir)
+			__entry->dir	= dir->i_ino;
 		__entry->mode		= mode;
 	),
 
-- 
2.41.0