linux-kernel - Re: [PATCH] locking/lockdep: Avoid potential access of invalid memory in lock

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Message-ID: <954086c4-d679-57d7-cc46-9ce6af2872a4@acm.org>
Date:   Mon, 3 Jan 2022 09:47:40 -0800
From:   Bart Van Assche <bvanassche@....org>
To:     Waiman Long <longman@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Will Deacon <will.deacon@....com>,
        Boqun Feng <boqun.feng@...il.com>
Cc:     linux-kernel@...r.kernel.org,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
Subject: Re: [PATCH] locking/lockdep: Avoid potential access of invalid memory
 in lock_class

On 1/2/22 18:35, Waiman Long wrote:
> -	WARN_ON_ONCE(!found);
> -	__lockdep_free_key_range(pf, key, 1);
> -	call_rcu_zapped(pf);
> -	graph_unlock();
> -out_irq:
> +	WARN_ON_ONCE(!found && debug_locks);

lockdep_unregister_key() should only be called for a registered key so I'd
like to keep the WARN_ON_ONCE(!found) here instead of changing it into
WARN_ON_ONCE(!found && debug_locks). Otherwise this patch looks good to me.

Thanks,

Bart.