Re: [patch 04/10] mm: shmem: save one radix tree lookup when truncating swapped pages

[Mel Gorman]

On Mon, Feb 03, 2014 at 07:53:36PM -0500, Johannes Weiner wrote:
> Page cache radix tree slots are usually stabilized by the page lock,
> but shmem's swap cookies have no such thing.  Because the overall
> truncation loop is lockless, the swap entry is currently confirmed by
> a tree lookup and then deleted by another tree lookup under the same
> tree lock region.
> 
> Use radix_tree_delete_item() instead, which does the verification and
> deletion with only one lookup.  This also allows removing the
> delete-only special case from shmem_radix_tree_replace().
> 
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
> Reviewed-by: Minchan Kim <minchan@xxxxxxxxxx>
> Reviewed-by: Rik van Riel <riel@xxxxxxxxxx>

Acked-by: Mel Gorman <mgorman@xxxxxxx>

-- 
Mel Gorman
SUSE Labs
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