Re: [PATCH 3/3] livepatch: Avoid potential RCU stalls in klp transition

[Josh Poimboeuf]

On Tue, Feb 11, 2025 at 02:24:37PM +0800, Yafang Shao wrote:
> +++ b/kernel/livepatch/transition.c
> @@ -491,9 +491,18 @@ void klp_try_complete_transition(void)
>                       complete = false;
>                       break;
>               }
> +
> +             /* Avoid potential RCU stalls */
> +             if (need_resched()) {
> +                     complete = false;
> +                     break;
> +             }
>       }
>       read_unlock(&tasklist_lock);
>  
> +     /* The above operation might be expensive. */
> +     cond_resched();
> +

This is also nasty, yet another reason to use rcu_read_lock() if we can.

Also, with the new lazy preemption model, I believe cond_resched() is
pretty much deprecated.

Also, for future patch sets, please also add lkml to cc.  Thanks.

-- 
Josh