Re: [PATCH] mm/mm_init: fix incorrect node_spanned_pages

[Wei Yang <richard.weiyang@gmail.com>]

On Tue, Jun 23, 2026 at 12:22:15PM +0300, Mike Rapoport wrote:
>Hi Wei,
>
>On Tue, Jun 23, 2026 at 08:35:07AM +0000, Wei Yang wrote:
>> On Mon, Jun 22, 2026 at 04:58:47PM +0300, Mike Rapoport wrote:
>> >On Mon, Jun 22, 2026 at 02:24:03AM +0000, Wei Yang wrote:
>> >> Current node_spanned_pages is got as a summation of all zone's spanned page
>> >> in calculate_node_totalpages(). Generally this is good, but if we use
>> >> kernelcore=mirror, it is would be wrong.
>> >>
>> >> As we already passed in node_start_pfn and node_end_pfn, fix this by get it
>> >> from (node_start_pfn - node_end_pfn) directly.
>> >> 
>> >> Fixes: 342332e6a925 ("mm/page_alloc.c: introduce kernelcore=mirror option")
>> >> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
>> >> Cc: Yuan Liu <yuan1.liu@intel.com>
>> >
>> >I queued it for now, will push to one of memblock branches after merge
>> >window closes.
>> >
>> 
>> After some investigation, I found current mirrored_kernelcore may still affect
>> memmap_init() in some aspects.
>> 
>> But how to fix is not sure, will prepare an RFC for discussion.
>
>After I applied your patch, I did some checks to see why
>mirrored_kernelcore causes us troubles. I found that unlike other variants
>of kernelcore/movablecore settings, mirrored_kernelcore creates zone
>overlap for no apparent reason. I did some git archaeology and I didn't
>find a justification for making overlapping pages absent in ZONE_NORMAL.
>
>So I came up with this cleanup:
>
>https://git.kernel.org/pub/scm/linux/kernel/git/rppt/linux.git/log/?h=kernelcore-mirror
>
>I'm waiting for the bots to chew on it before positing the patches.
> 

Ah, just the same as I do :-).

>> -- 
>> Wei Yang
>> Help you, Help me
>
>-- 
>Sincerely yours,
>Mike.

-- 
Wei Yang
Help you, Help me