Re: [PATCH v4] mm/kfence: print disabling or re-enabling message

[Marco Elver <elver@google.com>]

On Wed, May 18, 2022 at 03:31PM +0800, Jackie Liu wrote:
> From: Jackie Liu <liuyun01@kylinos.cn>
> 
> By printing information, we can friendly prompt the status change
> information of kfence by dmesg and record by syslog.
> 
> Also, set kfence_enabled to false only when needed.
> 
> Co-developed-by: Marco Elver <elver@google.com>

Signed-off-by: Marco Elver <elver@google.com>

> Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>

Reviewed-by: Marco Elver <elver@google.com>

> ---
>  v1->v2:
>    fixup by Marco Elver <elver@google.com>
>  v2->v3:
>    write kfence_enabled=false only true before
>  v3->v4:
>    cleanup
> 
>  mm/kfence/core.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/kfence/core.c b/mm/kfence/core.c
> index 11a954763be9..af0489d4d149 100644
> --- a/mm/kfence/core.c
> +++ b/mm/kfence/core.c
> @@ -67,8 +67,11 @@ static int param_set_sample_interval(const char *val, const struct kernel_param
>  	if (ret < 0)
>  		return ret;
>  
> -	if (!num) /* Using 0 to indicate KFENCE is disabled. */
> +	/* Using 0 to indicate KFENCE is disabled. */
> +	if (!num && READ_ONCE(kfence_enabled)) {
> +		pr_info("disabled\n");
>  		WRITE_ONCE(kfence_enabled, false);
> +	}
>  
>  	*((unsigned long *)kp->arg) = num;
>  
> @@ -874,6 +877,7 @@ static int kfence_enable_late(void)
>  
>  	WRITE_ONCE(kfence_enabled, true);
>  	queue_delayed_work(system_unbound_wq, &kfence_timer, 0);
> +	pr_info("re-enabled\n");
>  	return 0;
>  }
>  
> -- 
> 2.25.1
>