Re: [syzbot] Re: [syzbot] [pm?] possible deadlock in lock_system_sleep

[syzbot <syzbot+ace60642828c074eb913@syzkaller.appspotmail.com>]

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***

Subject: Re: [syzbot] [pm?] possible deadlock in lock_system_sleep
Author: lizhi.xu@windriver.com

#syz test

diff --git a/kernel/params.c b/kernel/params.c
index 0074d29c9b80..d19881fbb2ec 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -583,7 +583,9 @@ static ssize_t param_attr_store(const struct module_attribute *mattr,
 	if (!attribute->param->ops->set)
 		return -EPERM;
 
-	kernel_param_lock(mk->mod);
+	if (!kernel_param_trylock(mk->mod))
+		return -EPERM;
+
 	if (param_check_unsafe(attribute->param))
 		err = attribute->param->ops->set(buf, attribute->param);
 	else
@@ -607,6 +609,11 @@ void kernel_param_lock(struct module *mod)
 	mutex_lock(KPARAM_MUTEX(mod));
 }
 
+int kernel_param_trylock(struct module *mod)
+{
+	return mutex_trylock(KPARAM_MUTEX(mod));
+}
+
 void kernel_param_unlock(struct module *mod)
 {
 	mutex_unlock(KPARAM_MUTEX(mod));
diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
index bfb85fd13e1f..cbcbfd8db721 100644
--- a/include/linux/moduleparam.h
+++ b/include/linux/moduleparam.h
@@ -306,11 +306,15 @@ struct kparam_array
 
 #ifdef CONFIG_SYSFS
 extern void kernel_param_lock(struct module *mod);
+extern int kernel_param_trylock(struct module *mod);
 extern void kernel_param_unlock(struct module *mod);
 #else
 static inline void kernel_param_lock(struct module *mod)
 {
 }
+static inline int kernel_param_trylock(struct module *mod)
+{
+}
 static inline void kernel_param_unlock(struct module *mod)
 {
 }