Re: [PATCH v4 3/3] mm: fs: Invalidate BH LRU during page migration

[Andrew Morton]

On Fri, 19 Mar 2021 10:51:27 -0700 Minchan Kim <minchan@xxxxxxxxxx> wrote:

> Pages containing buffer_heads that are in one of the per-CPU
> buffer_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.
> 
> 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.
> 
> Tested-by: Oliver Sang <oliver.sang@xxxxxxxxx>
> Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
> Signed-off-by: Chris Goldsworthy <cgoldswo@xxxxxxxxxxxxxx>
> Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>

The signoff chain ordering might mean that Chris was the primary author, but
there is no From:him.  Please clarify?