Re: [PATCH 1/8] mm, compaction: don't isolate PageWriteback pages in MIGRATE_SYNC_LIGHT mode

[David Rientjes]

On Mon, 18 Jul 2016, Vlastimil Babka wrote:

> From: Hugh Dickins <hughd@xxxxxxxxxx>
> 
> At present MIGRATE_SYNC_LIGHT is allowing __isolate_lru_page() to
> isolate a PageWriteback page, which __unmap_and_move() then rejects
> with -EBUSY: of course the writeback might complete in between, but
> that's not what we usually expect, so probably better not to isolate it.
> 
> When tested by stress-highalloc from mmtests, this has reduced the number of
> page migrate failures by 60-70%.
> 
> Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
> Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
> Acked-by: Michal Hocko <mhocko@xxxxxxxx>

Acked-by: David Rientjes <rientjes@xxxxxxxxxx>