Re: [PATCH 7/9] kho: Report how much handover memory is preserved and restored

[sashiko-bot@kernel.org]

> Most memory the previous kernel preserved stays reserved until its user
> restores it through KHO, either to use it again or to free it. If
> nothing does, it stays reserved for as long as the kernel runs. On a
> hypervisor host that can be gigabytes, but amusingly nothing really
> shows it reliably. The host simply has less memory than it should, which
> is not exactly obvious.
> 
> All preserved memory is reserved in kho_preserved_memory_reserve(), and
> everything restored through KHO goes through kho_restore_page(), so KHO
> can count both easily. Let's add preserved_size and restored_size, in
> bytes, to /sys/kernel/kexec/kho_incoming/.
> 
> For example, after a live update preserving a 64 MiB memfd:
> 
>                      preserved_size  restored_size
>     before retrieval       67403776           8192
>     after retrieval        67403776       67395584
> 
> The 8 KiB left are the incoming KHO FDT and LUO's FLB header.
> 
> Signed-off-by: Chris Down <chris@chrisdown.name>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/cover.1794383544.git.chris@chrisdown.name?part=7