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Date: Wed, 27 May 2026 16:20:27 -0400
From: Steven Rostedt <rostedt@kernel.org>
To: Jens Remus <jremus@linux.ibm.com>
Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
 x86@kernel.org, Josh Poimboeuf <jpoimboe@kernel.org>, Indu Bhagat
 <ibhagatgnu@gmail.com>, Peter Zijlstra <peterz@infradead.org>, Dylan Hatch
 <dylanbhatch@google.com>, Thomas Gleixner <tglx@kernel.org>, Ingo Molnar
 <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, Dave Hansen
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 Desnoyers <mathieu.desnoyers@efficios.com>, Kees Cook <kees@kernel.org>,
 Sam James <sam@gentoo.org>, bpf@vger.kernel.org, linux-mm@kvack.org,
 Namhyung Kim <namhyung@kernel.org>, Andrii Nakryiko <andrii@kernel.org>,
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 <david@kernel.org>, Lorenzo Stoakes <ljs@kernel.org>, "Liam R. Howlett"
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 <gor@linux.ibm.com>, Ilya Leoshkevich <iii@linux.ibm.com>, "Steven Rostedt
 (Google)" <rostedt@goodmis.org>
Subject: Re: [PATCH v16 03/20] unwind_user/sframe: Store .sframe section
 data in per-mm maple tree
Message-ID: <20260527162027.277e744c@fedora>
In-Reply-To: <20260521142546.3908498-4-jremus@linux.ibm.com>
References: <20260521142546.3908498-1-jremus@linux.ibm.com>
	<20260521142546.3908498-4-jremus@linux.ibm.com>
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On Thu, 21 May 2026 16:25:29 +0200
Jens Remus <jremus@linux.ibm.com> wrote:

>  int sframe_remove_section(unsigned long sframe_start)
>  {
> -	return -ENOSYS;
> +	struct mm_struct *mm = current->mm;
> +	struct sframe_section *sec;
> +	unsigned long index = 0;
> +	bool found = false;
> +	int ret = 0;
> +
> +	guard(srcu)(&sframe_srcu);
> +
> +	mt_for_each(&mm->sframe_mt, sec, index, ULONG_MAX) {
> +		if (sec->sframe_start == sframe_start) {
> +			found = true;
> +			ret |= __sframe_remove_section(mm, sec);

Because this is all internal data, the __sframe_remove_section() should
never fail. Perhaps we should add a WARN_ON() if it does?

		if (sec->sframe_start == sframe_start) {
			ret |= __sframe_remove_section(mm, sec);
			WARN_ON(!found && ret);
			found = true;

-- Steve



> +		}
> +	}
> +
> +	if (!found || ret)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +