--- zzzz-none-000/linux-3.10.107/lib/bug.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/lib/bug.c	2021-02-04 17:41:59.000000000 +0000
@@ -37,6 +37,9 @@
 
     Jeremy Fitzhardinge <jeremy@goop.org> 2006
  */
+
+#define pr_fmt(fmt) fmt
+
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/kernel.h>
@@ -61,16 +64,22 @@
 static const struct bug_entry *module_find_bug(unsigned long bugaddr)
 {
 	struct module *mod;
+	const struct bug_entry *bug = NULL;
 
-	list_for_each_entry(mod, &module_bug_list, bug_list) {
-		const struct bug_entry *bug = mod->bug_table;
+	rcu_read_lock_sched();
+	list_for_each_entry_rcu(mod, &module_bug_list, bug_list) {
 		unsigned i;
 
+		bug = mod->bug_table;
 		for (i = 0; i < mod->num_bugs; ++i, ++bug)
 			if (bugaddr == bug_addr(bug))
-				return bug;
+				goto out;
 	}
-	return NULL;
+	bug = NULL;
+out:
+	rcu_read_unlock_sched();
+
+	return bug;
 }
 
 void module_bug_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
@@ -79,6 +88,8 @@
 	char *secstrings;
 	unsigned int i;
 
+	lockdep_assert_held(&module_mutex);
+
 	mod->bug_table = NULL;
 	mod->num_bugs = 0;
 
@@ -96,13 +107,16 @@
 	 * Strictly speaking this should have a spinlock to protect against
 	 * traversals, but since we only traverse on BUG()s, a spinlock
 	 * could potentially lead to deadlock and thus be counter-productive.
+	 * Thus, this uses RCU to safely manipulate the bug list, since BUG
+	 * must run in non-interruptive state.
 	 */
-	list_add(&mod->bug_list, &module_bug_list);
+	list_add_rcu(&mod->bug_list, &module_bug_list);
 }
 
 void module_bug_cleanup(struct module *mod)
 {
-	list_del(&mod->bug_list);
+	lockdep_assert_held(&module_mutex);
+	list_del_rcu(&mod->bug_list);
 }
 
 #else
@@ -153,15 +167,13 @@
 
 	if (warning) {
 		/* this is a WARN_ON rather than BUG/BUG_ON */
-		printk(KERN_WARNING "------------[ cut here ]------------\n");
+		pr_warn("------------[ cut here ]------------\n");
 
 		if (file)
-			printk(KERN_WARNING "WARNING: at %s:%u\n",
-			       file, line);
+			pr_warn("WARNING: at %s:%u\n", file, line);
 		else
-			printk(KERN_WARNING "WARNING: at %p "
-			       "[verbose debug info unavailable]\n",
-			       (void *)bugaddr);
+			pr_warn("WARNING: at %p [verbose debug info unavailable]\n",
+				(void *)bugaddr);
 
 		print_modules();
 		show_regs(regs);
@@ -174,12 +186,10 @@
 	printk(KERN_DEFAULT "------------[ cut here ]------------\n");
 
 	if (file)
-		printk(KERN_CRIT "kernel BUG at %s:%u!\n",
-		       file, line);
+		pr_crit("kernel BUG at %s:%u!\n", file, line);
 	else
-		printk(KERN_CRIT "Kernel BUG at %p "
-		       "[verbose debug info unavailable]\n",
-		       (void *)bugaddr);
+		pr_crit("Kernel BUG at %p [verbose debug info unavailable]\n",
+			(void *)bugaddr);
 
 	return BUG_TRAP_TYPE_BUG;
 }