Re: [PATCH v5 1/4] cacheinfo: Check for null last-level cache info

[Andreas Herrmann]

On Mon, Aug 26, 2024 at 10:16:32PM -0700, Ricardo Neri wrote:
> Before determining the validity of the last-level cache info, ensure that
> it has been allocated. Simply checking for non-zero cache_leaves() is not
> sufficient, as some architectures (e.g., Intel processors) have non-zero
> cache_leaves() before allocation.
> 
> Dereferencing NULL cacheinfo can occur in update_per_cpu_data_slice_size().
> This function iterates over all online CPUs. However, a CPU may have come
> online recently, but its cacheinfo may not have been allocated yet.
> 
> Reviewed-by: Sudeep Holla <sudeep.holla@xxxxxxx>
> Signed-off-by: Ricardo Neri <ricardo.neri-calderon@xxxxxxxxxxxxxxx>

Reviewed-by: Andreas Herrmann <aherrmann@xxxxxxx>
Tested-by: Andreas Herrmann <aherrmann@xxxxxxx>

Test was done with a system equipped with AMD Phenom II X6 1055T and
test kernels based on v6.11-rc5-176-g20371ba12063.


Thanks,
Andreas