On Sat, Jul 06, 2024 at 05:46:08PM +0200, Thomas Gleixner wrote:
>
> From: Huacai Chen <chenhuacai@xxxxxxxxxx>
>
> commit 6ef8eb5125722c241fd60d7b0c872d5c2e5dd4ca upstream.
>
> After the rework of "Parallel CPU bringup", the cmdline "nosmp" and
> "maxcpus=0" parameters are not working anymore. These parameters set
> setup_max_cpus to zero and that's handed to bringup_nonboot_cpus().
>
> The code there does a decrement before checking for zero, which brings it
> into the negative space and brings up all CPUs.
>
> Add a zero check at the beginning of the function to prevent this.
>
> [ tglx: Massaged change log ]
>
> Fixes: 18415f33e2ac4ab382 ("cpu/hotplug: Allow "parallel" bringup up to CPUHP_BP_KICK_AP_STATE")
> Fixes: 06c6796e0304234da6 ("cpu/hotplug: Fix off by one in cpuhp_bringup_mask()")
> Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Link: https://lore.kernel.org/r/20240618081336.3996825-1-chenhuacai@xxxxxxxxxxx
> ---
> kernel/cpu.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> --- a/kernel/cpu.c
Now queued up, thanks.
greg k-h
