Re: [PATCH] ftrace: Use rcu_assign_pointer() for tmp_ops filter hash

[Jiri Olsa <olsajiri@gmail.com>]

On Fri, Sep 11, 2026 at 10:25:12PM +0800, Leon Hwang wrote:
> tmp_ops.func_hash->filter_hash is annotated __rcu, but
> update_ftrace_direct_mod() assigns hash to it directly. Sparse reports an
> address-space mismatch.
> 
> Use rcu_assign_pointer() for the assignment.
> 
> Fixes: 50b35c9e50a8 ("ftrace: Use hash argument for tmp_ops in update_ftrace_direct_mod")
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202609110704.Q3M5vCDV-lkp@intel.com/
> Signed-off-by: Leon Hwang <leon.hwang@linux.dev>

Acked-by: Jiri Olsa <jolsa@kernel.org>

thanks,
jirka

> ---
>  kernel/trace/ftrace.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index 53d5db60bfa5..673a54fdf392 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -6675,7 +6675,7 @@ int update_ftrace_direct_mod(struct ftrace_ops *ops, struct ftrace_hash *hash, b
>  
>  	/* Enable the tmp_ops to have the same functions as the hash object. */
>  	ftrace_ops_init(&tmp_ops);
> -	tmp_ops.func_hash->filter_hash = hash;
> +	rcu_assign_pointer(tmp_ops.func_hash->filter_hash, hash);
>  
>  	err = register_ftrace_function_nolock(&tmp_ops);
>  	if (err)
> -- 
> 2.55.0
>