Re: [PATCH] powerpc/kexec_file: account hot-pluggable memory while estimating FDT size

[Sourabh Jain <sourabhjain@linux.ibm.com>]

Gentle reminder, any comments and suggestions on this fix.

- Sourabh

On 15/12/22 14:08, Sourabh Jain wrote:
> On Systems where online memory is lesser compared to max memory, the
> kexec_file_load system call may fail to load the kdump kernel with the
> below errors:
>
>      "Failed to update fdt with linux,drconf-usable-memory property"
>      "Error setting up usable-memory property for kdump kernel"
>
> This happens because the size estimation for usable memory properties
> for the kdump kernel's FDT is based on the online memory whereas the
> usable memory properties include max memory. In short, the hot-pluggable
> memory is not accounted for while estimating the size of the usable
> memory properties.
>
> The issue is addressed by calculating usable memory property size using
> max hotplug address instead of the last online memory address.
>
> Fixes: 2377c92e37fe ("powerpc/kexec_file: fix FDT size estimation for kdump kernel")
> Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
> ---
>   arch/powerpc/kexec/file_load_64.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c
> index 349a781cea0b3..2c3fd6fe6bc94 100644
> --- a/arch/powerpc/kexec/file_load_64.c
> +++ b/arch/powerpc/kexec/file_load_64.c
> @@ -947,7 +947,7 @@ unsigned int kexec_extra_fdt_size_ppc64(struct kimage *image)
>   	 * linux,drconf-usable-memory properties. Get an approximate on the
>   	 * number of usable memory entries and use for FDT size estimation.
>   	 */
> -	usm_entries = ((memblock_end_of_DRAM() / drmem_lmb_size()) +
> +	usm_entries = ((memory_hotplug_max() / drmem_lmb_size()) +
>   		       (2 * (resource_size(&crashk_res) / drmem_lmb_size())));
>   	return (unsigned int)(usm_entries * sizeof(u64));
>   }