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Date: Tue, 19 Aug 2025 16:53:45 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Jiri Olsa <jolsa@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>, Andrii Nakryiko <andrii@kernel.org>,
	"Masami Hiramatsu (Google)" <mhiramat@kernel.org>,
	bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
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	Thomas =?iso-8859-1?Q?Wei=DFschuh?= <thomas@t-8ch.de>,
	Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCHv6 perf/core 08/22] uprobes/x86: Add mapping for optimized
 uprobe trampolines
Message-ID: <20250819145345.GL3289052@noisy.programming.kicks-ass.net>
References: <20250720112133.244369-1-jolsa@kernel.org>
 <20250720112133.244369-9-jolsa@kernel.org>
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In-Reply-To: <20250720112133.244369-9-jolsa@kernel.org>

On Sun, Jul 20, 2025 at 01:21:18PM +0200, Jiri Olsa wrote:
> +static void destroy_uprobe_trampoline(struct uprobe_trampoline *tramp)
> +{
> +	/*
> +	 * We do not unmap and release uprobe trampoline page itself,
> +	 * because there's no easy way to make sure none of the threads
> +	 * is still inside the trampoline.
> +	 */
> +	hlist_del(&tramp->node);
> +	kfree(tramp);
> +}

I am somewhat confused; isn't this called from
__mmput()->uprobe_clear_state()->arch_uprobe_clear_state ?

At that time we don't have threads anymore and mm is about to be
destroyed anyway.