linux-kernel - Re: [PATCH perf/core 07/22] uprobes: Remove breakpoint in unapply_uprobe under mmap_write

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Message-ID: <20250427142400.GB9350@redhat.com>
Date: Sun, 27 Apr 2025 16:24:01 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Jiri Olsa <jolsa@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>,
	Andrii Nakryiko <andrii@...nel.org>, bpf@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
	x86@...nel.org, Song Liu <songliubraving@...com>,
	Yonghong Song <yhs@...com>,
	John Fastabend <john.fastabend@...il.com>,
	Hao Luo <haoluo@...gle.com>, Steven Rostedt <rostedt@...dmis.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Alan Maguire <alan.maguire@...cle.com>,
	David Laight <David.Laight@...LAB.COM>,
	Thomas Weißschuh <thomas@...ch.de>,
	Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH perf/core 07/22] uprobes: Remove breakpoint in
 unapply_uprobe under mmap_write_lock

On 04/21, Jiri Olsa wrote:
>
> @@ -1483,7 +1483,7 @@ static int unapply_uprobe(struct uprobe *uprobe, struct mm_struct *mm)
>  	struct vm_area_struct *vma;
>  	int err = 0;
>
> -	mmap_read_lock(mm);
> +	mmap_write_lock(mm);

So uprobe_write_opcode() is always called under down_write(), right?
Then this

	* Called with mm->mmap_lock held for read or write.

comment should be probably updated.

And perhaps the comment above mmap_write_lock() in register_for_each_vma()
should be updated too... or even removed.

Oleg.