There is no page cache for the procfs, so do not scan the
inodes in procfs.

Signed-off-by: Huang Shijie <huangsj@hygon.cn>
---
 fs/drop_caches.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/drop_caches.c b/fs/drop_caches.c
index 49f56a598ecb..1959090089af 100644
--- a/fs/drop_caches.c
+++ b/fs/drop_caches.c
@@ -5,6 +5,7 @@
 
 #include <linux/pagemap.h>
 #include <linux/kernel.h>
+#include <linux/magic.h>
 #include <linux/mm.h>
 #include <linux/fs.h>
 #include <linux/writeback.h>
@@ -20,6 +21,9 @@ static void drop_pagecache_sb(struct super_block *sb, void *unused)
 {
 	struct inode *inode, *toput_inode = NULL;
 
+	if (sb->s_magic == PROC_SUPER_MAGIC)
+		return;
+
 	spin_lock(&sb->s_inode_list_lock);
 	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
 		spin_lock(&inode->i_lock);
-- 
2.53.0