Messages in this thread | | | Subject | Re: [PATCH v3 3/3] mm: fs: Invalidate BH LRU during page migration | From | David Hildenbrand <> | Date | Fri, 12 Mar 2021 10:03:42 +0100 |
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On 10.03.21 17:14, Minchan Kim wrote: > ffer_head LRU caches will be pinned and thus cannot be migrated. > This can prevent CMA allocations from succeeding, which are often used > on platforms with co-processors (such as a DSP) that can only use > physically contiguous memory. It can also prevent memory > hot-unplugging from succeeding, which involves migrating at least > MIN_MEMORY_BLOCK_SIZE bytes of memory, which ranges from 8 MiB to 1 > GiB based on the architecture in use.
Actually, it's memory_block_size_bytes(), which can be even bigger (IIRC, 128MiB..2 GiB on x86-64) that fails to get offlined. But that will prevent bigger granularity (e.g., a whole DIMM) from getting unplugged.
> > Correspondingly, invalidate the BH LRU caches before a migration > starts and stop any buffer_head from being cached in the LRU caches, > until migration has finished.
Sounds sane to me.
-- Thanks,
David / dhildenb
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