mm/hwpoison-inject.c: change permission of corrupt-pfn/unpoison-pfn to 0200

Hwpoison injection doesn't implement read method for
corrupt-pfn/unpoison-pfn attributes:

# cat /sys/kernel/debug/hwpoison/corrupt-pfn
cat: /sys/kernel/debug/hwpoison/corrupt-pfn: Permission denied
# cat /sys/kernel/debug/hwpoison/unpoison-pfn
cat: /sys/kernel/debug/hwpoison/unpoison-pfn: Permission denied

This patch changes the permission of corrupt-pfn/unpoison-pfn to 0200.
Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/hwpoison-inject.c

@@ -88,12 +88,12 @@ static int pfn_inject_init(void)
 	 * hardware status change, hence do not require hardware support.
 	 * They are mainly for testing hwpoison in software level.
 	 */
-	dentry = debugfs_create_file("corrupt-pfn", 0600, hwpoison_dir,
+	dentry = debugfs_create_file("corrupt-pfn", 0200, hwpoison_dir,
 					  NULL, &hwpoison_fops);
 	if (!dentry)
 		goto fail;
 
-	dentry = debugfs_create_file("unpoison-pfn", 0600, hwpoison_dir,
+	dentry = debugfs_create_file("unpoison-pfn", 0200, hwpoison_dir,
 				     NULL, &unpoison_fops);
 	if (!dentry)
 		goto fail;