Re: [PATCH v4 01/11] liveupdate: Add LIVEUPDATE_GUEST_MEMFD config option

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The patch introduces the `LIVEUPDATE_GUEST_MEMFD` Kconfig option claiming to enable a new feature, but there is no actual implementation provided.
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--- Patch [1]: [PATCH v4 01/11] liveupdate: Add LIVEUPDATE_GUEST_MEMFD config option ---
commit e0c3fde657d56c548cd9a7467d2143f0f42c5242
Author: Tarun Sahu <tarunsahu@google.com>

liveupdate: Add LIVEUPDATE_GUEST_MEMFD config option

This commit introduces the LIVEUPDATE_GUEST_MEMFD Kconfig option, which aims
to enable live update support for KVM guest_memfd files.

> diff --git a/kernel/liveupdate/Kconfig b/kernel/liveupdate/Kconfig
> index 1a8513f16ef7c..0bbc4037192e9 100644
> --- a/kernel/liveupdate/Kconfig
> +++ b/kernel/liveupdate/Kconfig
> @@ -88,4 +88,19 @@ config LIVEUPDATE_MEMFD
>  
>  	  If unsure, say N.
>  
> +config LIVEUPDATE_GUEST_MEMFD
> +	bool "Live update support for guest_memfd"
> +	depends on LIVEUPDATE
> +	depends on KVM_GUEST_MEMFD
> +	default LIVEUPDATE

[Severity: Medium]
Is the implementation for this feature missing from this patch?

The commit message notes that this patch enables live update support for KVM
guest_memfd files, but the newly added LIVEUPDATE_GUEST_MEMFD symbol appears
to be unreferenced in the tree. Since there are no Makefiles, C files, or
preprocessor checks that use it, this currently acts as dead code.

Could the implementation be missing, or was this intended to be introduced as
part of a larger series where the symbol is used in a subsequent patch?

> +	help
> +	  Enable live update support for KVM guest_memfd files. This allows
> +	  preserving VM Memory backed by guest_memfd file across kernel live
> +	  updates.
> +
> +	  This can only be used for the guest_memfd that are fully-shared
> +	  and pre-faulted.
> +
> +	  If unsure, say N.
> +
>  endmenu

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Sashiko AI review · https://sashiko.dev/#/patchset/20260728121138.1103610-1-tarunsahu@google.com?part=1