[PATCH] modules: wait do_free_init correctly

[Changbin Du]

The commit 1a7b7d922081 ("modules: Use vmalloc special flag") moves
do_free_init() into a global workqueue instead of call_rcu(). So now
we should wait it via flush_work().

Fixes: 1a7b7d922081 ("modules: Use vmalloc special flag")
Signed-off-by: Changbin Du <changbin.du@xxxxxxxxxx>
Cc: Xiaoyi Su <suxiaoyi@xxxxxxxxxx>
---
 include/linux/moduleloader.h | 2 ++
 init/main.c                  | 5 +++--
 kernel/module/main.c         | 5 +++++
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/include/linux/moduleloader.h b/include/linux/moduleloader.h
index 001b2ce83832..f3d445d8ccd0 100644
--- a/include/linux/moduleloader.h
+++ b/include/linux/moduleloader.h
@@ -115,6 +115,8 @@ int module_finalize(const Elf_Ehdr *hdr,
 		    const Elf_Shdr *sechdrs,
 		    struct module *mod);
 
+void flush_module_init_free_work(void);
+
 /* Any cleanup needed when module leaves. */
 void module_arch_cleanup(struct module *mod);
 
diff --git a/init/main.c b/init/main.c
index e24b0780fdff..f0b7e21ac67f 100644
--- a/init/main.c
+++ b/init/main.c
@@ -99,6 +99,7 @@
 #include <linux/init_syscalls.h>
 #include <linux/stackdepot.h>
 #include <linux/randomize_kstack.h>
+#include <linux/moduleloader.h>
 #include <net/net_namespace.h>
 
 #include <asm/io.h>
@@ -1402,11 +1403,11 @@ static void mark_readonly(void)
 	if (rodata_enabled) {
 		/*
 		 * load_module() results in W+X mappings, which are cleaned
-		 * up with call_rcu().  Let's make sure that queued work is
+		 * up with init_free_wq. Let's make sure that queued work is
 		 * flushed so that we don't hit false positives looking for
 		 * insecure pages which are W+X.
 		 */
-		rcu_barrier();
+		flush_module_init_free_work();
 		mark_rodata_ro();
 		rodata_test();
 	} else
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 98fedfdb8db5..1943ccb7414f 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -2486,6 +2486,11 @@ static void do_free_init(struct work_struct *w)
 	}
 }
 
+void flush_module_init_free_work(void)
+{
+	flush_work(&init_free_wq);
+}
+
 #undef MODULE_PARAM_PREFIX
 #define MODULE_PARAM_PREFIX "module."
 /* Default value for module->async_probe_requested */
-- 
2.25.1