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Date: Mon, 01 Sep 2025 15:30:20 +0200
From: "Arnd Bergmann" <arnd@...db.de>
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Subject: Re: [PATCH v2 3/4] arch: copy_thread: pass clone_flags as u64

On Mon, Sep 1, 2025, at 15:09, Simon Schuster via B4 Relay wrote:
> From: Simon Schuster <schuster.simon@...mens-energy.com>
>
> With the introduction of clone3 in commit 7f192e3cd316 ("fork: add
> clone3") the effective bit width of clone_flags on all architectures was
> increased from 32-bit to 64-bit, with a new type of u64 for the flags.
> However, for most consumers of clone_flags the interface was not
> changed from the previous type of unsigned long.
>
> While this works fine as long as none of the new 64-bit flag bits
> (CLONE_CLEAR_SIGHAND and CLONE_INTO_CGROUP) are evaluated, this is still
> undesirable in terms of the principle of least surprise.
>
> Thus, this commit fixes all relevant interfaces of the copy_thread
> function that is called from copy_process to consistently pass
> clone_flags as u64, so that no truncation to 32-bit integers occurs on
> 32-bit architectures.
>
> Signed-off-by: Simon Schuster <schuster.simon@...mens-energy.com>

Reviewed-by: Arnd Bergmann <arnd@...db.de>

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