On Wed, Mar 02, 2022 at 10:14:00AM +0100, Miroslav Benes wrote:

Hi,

On Wed, 2 Mar 2022, cgel.zte@gmail.com wrote:

quoted

From: Lv Ruyi (CGEL ZTE) <redacted>

Kfree_rcu() usually results in even simpler code than does 
synchronize_rcu() without synchronize_rcu()'s multi-millisecond
latency, so replace synchronize_rcu() with kfree_rcu().

Reported-by: Zeal Robot <redacted>
Signed-off-by: Lv Ruyi (CGEL ZTE) <redacted>
---
 kernel/module.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/module.c b/kernel/module.c
index 6cea788fd965..767b5f9e5819 100644
--- a/kernel/module.c
+++ b/kernel/module.c

@@ -4138,8 +4138,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
  ddebug_cleanup:
 	ftrace_release_mod(mod);
 	dynamic_debug_remove(mod, info->debug);
-	synchronize_rcu();
-	kfree(mod->args);
+	kfree_rcu(mod->args);

this has been proposed already. synchronize_rcu() and kfree() here are not 
really tied together. See the discussion at 
https://lore.kernel.org/all/alpine.LSU.2.21.2111301132220.3922@pobox.suse.cz/T/#u (local)

Aaron, can you add a nice comment here to explain this while at it?
Otherwise this will be lost tribal knowledge.

Lv Ruyi, please open source your Zeal Robot. Thanks!

  Luis