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Subject: Re: [PATCH v5] tracepoint: Do not fail unregistering a probe due to
 memory failure
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Matt Mullins <mmullins@mmlx.us>, paulmck <paulmck@kernel.org>,
        Ingo Molnar <mingo@redhat.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Dmitry Vyukov <dvyukov@google.com>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        Andrii Nakryiko <andriin@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@chromium.org>,
        Kees Cook <keescook@chromium.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>
References: <20210127170721.58bce7cc@gandalf.local.home>
 <ac000ed4-3eeb-60df-f896-c05cabb4c1c9@ozlabs.ru>
 <20210130093626.0b7b3b1b@oasis.local.home>
 <20210130094211.719f03a6@oasis.local.home>
From:   Alexey Kardashevskiy <aik@ozlabs.ru>
Message-ID: <13608cdc-2068-6340-6795-28944c9fe3ca@ozlabs.ru>
Date:   Mon, 1 Feb 2021 12:18:34 +1100
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On 31/01/2021 01:42, Steven Rostedt wrote:
> On Sat, 30 Jan 2021 09:36:26 -0500
> Steven Rostedt <rostedt@goodmis.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