Hugepage migration

[Baruch Even]

Hi,

We found an issue with newer kernels (5.13+) that are found on newer OSes
(Ubuntu22, Rocky9, Ubuntu20 with kernel 5.15) where a 2M page that was
allocated for DPDK was migrated (moved into another physical page) when a
1G page was allocated.

>From our reading of the kernel commits this started with commit
ae37c7ff79f1f030e28ec76c46ee032f8fd07607
    mm: make alloc_contig_range handle in-use hugetlb pages

This caused what looked like memory corruptions to us and cases where the
rings were moved from their physical location and communication was no
longer possible.

I wanted to ask if anyone else hit this issue and what mitigations are
available?

We are currently looking at using a kernel driver to pin the pages but I
expect that this issue will affect others and that a more general approach
is needed.

Thanks,
Baruch

-- 
Baruch Even
Platform Technical Lead,  WEKA
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