Re: [PATCH v4 03/19] kho, memfd_luo: Reference struct kho_vmalloc via serialized pointer

[sashiko-bot@kernel.org]

> Subsystems preserving vmalloc allocations currently embed struct
> kho_vmalloc directly by value in their serialized structures or device
> tree properties. For example, struct memfd_luo_ser embeds struct
> kho_vmalloc folios, and test_kho writes the structure directly into the
> folios_info FDT property.
> 
> Embedding struct kho_vmalloc directly couples the containing layout's
> field offsets and size to struct kho_vmalloc. Any modification to struct
> kho_vmalloc shifts subsequent fields in the containing structure and
> breaks the handover ABI across kexec.
> 
> Convert callers to hold a DECLARE_KHOSER_PTR pointer to struct
> kho_vmalloc instead of embedding it by value. In memfd_luo, allocate the
> main structure and struct kho_vmalloc in the same preserved folio, placing
> struct kho_vmalloc in the remaining 8-byte-aligned space, and bump the
> compatibility string to memfd-v3. In test_kho, place struct kho_vmalloc
> in the remaining space of the FDT folio, store the serialized pointer in
> the folios_info property, and bump the compatibility string to
> kho-test-v2.
> 
> Signed-off-by: Tarun Sahu <tarunsahu@google.com>

Sashiko has reviewed this patch and found no issues.

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