linux-kernel - Re: [PATCH v5] tracepoint: Do not fail unregistering a probe due to memory failure

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Date:   Mon, 1 Feb 2021 12:18:34 +1100
From:   Alexey Kardashevskiy <aik@...abs.ru>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Matt Mullins <mmullins@...x.us>, paulmck <paulmck@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        Kees Cook <keescook@...omium.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>
Subject: Re: [PATCH v5] tracepoint: Do not fail unregistering a probe due to
 memory failure



On 31/01/2021 01:42, Steven Rostedt wrote:
> On Sat, 30 Jan 2021 09:36:26 -0500
> Steven Rostedt <rostedt@...dmis.org> wrote:
> 
>> Do you still have the same crash with v3 (that's the one I'm going to
>> go with for now.)
>>
>>   https://lore.kernel.org/r/20201118093405.7a6d2290@gandalf.local.home
> 
> Just curious, does the following patch fix it for v5?


Yes it does!


> 
> -- Steve
> 
> diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
> index 7261fa0f5e3c..cf3a6d104fdb 100644
> --- a/kernel/tracepoint.c
> +++ b/kernel/tracepoint.c
> @@ -306,6 +306,7 @@ static int tracepoint_remove_func(struct tracepoint *tp,
>   			tp->unregfunc();
>   
>   		static_key_disable(&tp->key);
> +		tracepoint_synchronize_unregister();
>   		rcu_assign_pointer(tp->funcs, tp_funcs);
>   	} else {
>   		rcu_assign_pointer(tp->funcs, tp_funcs);
> 

-- 
Alexey