linux-kernel - Re: [PATCH v2] rcu: Dump memory object info if callback function is invalid

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Date:   Mon, 14 Nov 2022 15:05:22 +0800
From:   "Leizhen (ThunderTown)" <thunder.leizhen@...wei.com>
To:     "Elliott, Robert (Servers)" <elliott@....com>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        "Neeraj Upadhyay" <quic_neeraju@...cinc.com>,
        Josh Triplett <josh@...htriplett.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        "rcu@...r.kernel.org" <rcu@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] rcu: Dump memory object info if callback function is
 invalid



On 2022/11/11 23:50, Elliott, Robert (Servers) wrote:
> 
> 
>> +static inline void debug_rcu_head_callback(struct rcu_head *rhp)
>> +{
>> +	if (unlikely(!rhp->func))
>> +		mem_dump_obj(rhp);
>> +}
>> +
> 
> The mm/util.c definition of mem_dump_object() says:
>  * This function uses pr_cont(), so that the caller is expected to have
>  * printed out whatever preamble is appropriate.
> 
> so this needs to call pr_alert() or pr_err() before that to explain what
> is being printed (with no \n), like these:
> 
> kernel/rcu/rcutorture.c: pr_alert("mem_dump_obj(%px):", &rhp);
> kernel/rcu/rcutorture.c: mem_dump_obj(&rhp);
> ...
> kernel/rcu/tree.c: pr_err("%s(): Double-freed CB %p->%pS()!!!  ", __func__, head, head->func);
> kernel/rcu/tree.c: mem_dump_obj(head);

Yes, right, thanks.

> 
> 
> .
> 

-- 
Regards,
  Zhen Lei