Re: [PATCH v2 2/3] kho: skip zero-sized lowmem and global bootmem areas

[Pratyush Yadav]

On Wed, Nov 04 2026, Mike Rapoport (Microsoft) wrote:

> The lowmem and the global bootmem areas can have zero size, for example
> when none or all of the memory is below ARCH_LOW_ADDRESS_LIMIT, or when
> either of those areas is explicitly set to zero with kho_bootmem=.
>
> For a zero-sized allocation memblock returns an address without reserving
> anything, and that empty area is recorded in kho_bootmem. If there is no
> memory below ARCH_LOW_ADDRESS_LIMIT, allocation of the empty lowmem area
> fails and KHO gets disabled.
>
> Extract a helper that checks for zero size and allocates memory from
> memblock, and use it to skip empty areas the same way as empty per-node
> areas are skipped.
>
> Fixes: 3dc92c311498 ("kexec: add Kexec HandOver (KHO) generation helpers")
> Reported-by: Chen Pei <cp0613@xxxxxxxxxxxxxxxxx>
> Closes: https://lore.kernel.org/all/20261026131851.9942-1-cp0613@xxxxxxxxxxxxxxxxx
> Signed-off-by: Mike Rapoport (Microsoft) <rppt@xxxxxxxxxx>

Reviewed-by: Pratyush Yadav <pratyush@xxxxxxxxxx>

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-- 
Regards,
Pratyush Yadav