linux-kernel - Re: [PATCH] ftrace: Prevent RCU stall on PREEMPT

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Date:   Tue, 13 Dec 2022 19:04:41 -0300
From:   "Guilherme G. Piccoli" <gpiccoli@...lia.com>
To:     rostedt@...dmis.org
Cc:     linux-kernel@...r.kernel.org,
        "Masami Hiramatsu (Google)" <mhiramat@...nel.org>,
        rcu@...r.kernel.org, kernel-dev@...lia.com, kernel@...ccoli.net,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH] ftrace: Prevent RCU stall on PREEMPT_VOLUNTARY kernels



On 16/11/2022 03:36, Masami Hiramatsu (Google) wrote:
> On Tue, 15 Nov 2022 17:48:47 -0300
> "Guilherme G. Piccoli" <gpiccoli@...lia.com> wrote:
> 
>> The function match_records() may take a while due to a large
>> number of string comparisons, so when in PREEMPT_VOLUNTARY
>> kernels we could face RCU stalls due to that.
>>
>> Add a cond_resched() to prevent that.
>>
>> Suggested-by: Steven Rostedt <rostedt@...dmis.org>
>> Acked-by: Paul E. McKenney <paulmck@...nel.org> # from RCU CPU stall warning perspective
>> Cc: Masami Hiramatsu <mhiramat@...nel.org>
>> Cc: Mark Rutland <mark.rutland@....com>
>> Signed-off-by: Guilherme G. Piccoli <gpiccoli@...lia.com>
> 
> This looks good to me.
> 
> Acked-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>
> 
> Thanks!
> 

Hi Steve, sorry to annoy, just a regular ping to see if we can get this
into 6.2 (if too late, not a huge deal).

Thanks,


Guilherme