Re: [PATCH v2 2/4] copy_process: pass clone_flags as u64 across calltree

Arnd Bergmann
2025-09-01T13:35:31Z

On Mon, Sep 1, 2025, at 15:09, Simon Schuster via B4 Relay wrote:
> From: Simon Schuster <schuster.simon@siemens-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 callees to
> sys_clone3/copy_process (excluding the architecture-specific
> copy_thread) 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@siemens-energy.com>
> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>

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