RE: [PATCH v8 1/2] mm/memory_hotplug: make shrink_zone_span() more robust

[Liu, Yuan1]

> -----Original Message-----
> From: Wei Yang <richard.weiyang@xxxxxxxxx>
> Sent: Friday, September 4, 2026 10:42 AM
> To: Liu, Yuan1 <yuan1.liu@xxxxxxxxx>
> Cc: David Hildenbrand <david@xxxxxxxxxx>; Oscar Salvador
> <osalvador@xxxxxxx>; Mike Rapoport <rppt@xxxxxxxxxx>; Wei Yang
> <richard.weiyang@xxxxxxxxx>; linux-mm@xxxxxxxxx; Zou, Nanhai
> <nanhai.zou@xxxxxxxxx>; Chen Zhang <zhangchen.kidd@xxxxxx>; Zeng, Jason
> <jason.zeng@xxxxxxxxx>; Chen, Yu C <yu.c.chen@xxxxxxxxx>; Deng, Pan
> <pan.deng@xxxxxxxxx>; Li, Tianyou <tianyou.li@xxxxxxxxx>; linux-
> kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v8 1/2] mm/memory_hotplug: make shrink_zone_span()
> more robust
> 
> On Tue, Sep 01, 2026 at 01:29:49AM -0400, Yuan Liu wrote:
> >From: "David Hildenbrand (Arm)" <david@xxxxxxxxxx>
> >
> >Let's make shrink_zone_span() more robust by checking in
> >find_smallest_section_pfn() / find_biggest_section_pfn() that the
> >start and end PFNs of the subsection are within the zone.
> 
> Either the start or end PFN is within the zone?

sure, will change it as you suggested.

> >While at it, clean up the function by factoring the core check out
> >into subsection_overlaps_zone().
> >
> >There likely is no need to check the nid first. We require
> >SPARSEMEM_VMEMMAP_ENABLE, where pfn_to_page() is cheap, and
> >pfn_to_nid() on CONFIG_NUMA would call pfn_to_page() either way.
> >So let's just drop that for now.
> >
> >Signed-off-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>
> >Tested-by: Yuan Liu <yuan1.liu@xxxxxxxxx>
> >Signed-off-by: Yuan Liu <yuan1.liu@xxxxxxxxx>
> 
> Otherwise, LGTM.
> 
> Reviewed-by: Wei Yang <richard.weiyang@xxxxxxxxx>

Thanks for your review.

Best Regards,
Liu, Yuan

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> Wei Yang
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