/proc/kcore: fix seeking

From: Dave Anderson <[email protected]>

Commit 34aacb2920667d405a8df15968b7f71ba46c8f18 ("procfs: Use generic_file_llseek in /proc/kcore") broke seeking on /proc/kcore. This changes it back to use default_llseek in order to restore the original behavior.

The problem with generic_file_llseek is that it only allows seeks up to inode->i_sb->s_maxbytes, which is 2GB-1 on procfs, where the memory file offset values in the /proc/kcore PT_LOAD segments may exceed or start beyond that offset value.

A similar revert was made for /proc/vmcore.

---

@@ -558,7 +558,7 @@ static int open_kcore(struct inode *inod
 static const struct file_operations proc_kcore_operations = {
 	.read		= read_kcore,
 	.open		= open_kcore,
-	.llseek		= generic_file_llseek,
+	.llseek		= default_llseek,
 };
 
 #ifdef CONFIG_MEMORY_HOTPLUG