Re: [resend] Revert "powerpc/powernv: Increase memory block size to 1GB on radix"

[rashmica <rashmica.g@gmail.com>]

Tested hot-unplugging dimm device on radix guest on p9 host with KVM.


On 01/05/18 12:57, Balbir Singh wrote:
> This commit was a stop-gap to prevent crashes on hotunplug, caused by
> the mismatch between the 1G mappings used for the linear mapping and the
> memory block size. Those issues are now resolved because we split the
> linear mapping at hotunplug time if necessary, as implemented in commit
> 4dd5f8a99e79 ("powerpc/mm/radix: Split linear mapping on hot-unplug").
>
> Signed-off-by: Balbir Singh <bsingharora@gmail.com>
> Signed-off-by: Michael Neuling <mikey@neuling.org>
Tested-by: Rashmica Gupta <rashmica.g@gmail.com>
> ---
>
> Resend with a newer commit message grabbed from an email sent by mpe.
>
>  arch/powerpc/platforms/powernv/setup.c | 10 +---------
>  1 file changed, 1 insertion(+), 9 deletions(-)
>
> diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
> index ef8c9ce53a61..fa63d3fff14c 100644
> --- a/arch/powerpc/platforms/powernv/setup.c
> +++ b/arch/powerpc/platforms/powernv/setup.c
> @@ -356,15 +356,7 @@ static void pnv_kexec_cpu_down(int crash_shutdown, int secondary)
>  #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
>  static unsigned long pnv_memory_block_size(void)
>  {
> -	/*
> -	 * We map the kernel linear region with 1GB large pages on radix. For
> -	 * memory hot unplug to work our memory block size must be at least
> -	 * this size.
> -	 */
> -	if (radix_enabled())
> -		return 1UL * 1024 * 1024 * 1024;
> -	else
> -		return 256UL * 1024 * 1024;
> +	return 256UL * 1024 * 1024;
>  }
>  #endif
>