jump_label: disable preemption around __module_text_address().

Steven reported a warning caused by not holding module_mutex or
rcu_read_lock_sched: his backtrace was corrupted but a quick audit
found this possible cause.  It's wrong anyway...

Reported-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 4 insertions, 1 deletions

diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 0dbea887d625..0eef93962a91 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -284,11 +284,14 @@ static int __jump_label_mod_text_reserved(void *start, void *end)
 {
         struct module *mod;
 
+        preempt_disable();
         mod = __module_text_address((unsigned long)start);
+        WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
+        preempt_enable();
+
         if (!mod)
                 return 0;
 
-        WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
 
         return __jump_label_text_reserved(mod->jump_entries,
                                 mod->jump_entries + mod->num_jump_entries,