On Mon, Oct 27, 2025 at 7:05 PM David Matlack <[email protected]> wrote: > > On Mon, Oct 20, 2025 at 5:09 PM Pasha Tatashin > <[email protected]> wrote: > > > > KHO allocates metadata for its preserved memory map using the slab > > allocator via kzalloc(). This metadata is temporary and is used by the > > next kernel during early boot to find preserved memory. > > > > A problem arises when KFENCE is enabled. kzalloc() calls can be > > randomly intercepted by kfence_alloc(), which services the allocation > > from a dedicated KFENCE memory pool. This pool is allocated early in > > boot via memblock. > > > > When booting via KHO, the memblock allocator is restricted to a "scratch > > area", forcing the KFENCE pool to be allocated within it. This creates a > > conflict, as the scratch area is expected to be ephemeral and > > overwriteable by a subsequent kexec. If KHO metadata is placed in this > > KFENCE pool, it leads to memory corruption when the next kernel is > > loaded. > > > > To fix this, modify KHO to allocate its metadata directly from the buddy > > allocator instead of slab. > > > > Fixes: fc33e4b44b27 ("kexec: enable KHO support for memory preservation") > > Signed-off-by: Pasha Tatashin <[email protected]> > > Reviewed-by: Pratyush Yadav <[email protected]> > > Reviewed-by: David Matlack <[email protected]>
Thank you, Pasha
