Re: [PATCH v2 08/28] gup: Handle page split race more efficiently

[Christoph Hellwig]

On Mon, Jan 10, 2022 at 04:23:46AM +0000, Matthew Wilcox (Oracle) wrote:
> If we hit the page split race, the current code returns NULL which will
> presumably trigger a retry under the mmap_lock.  This isn't necessary;
> we can just retry the compound_head() lookup.  This is a very minor
> optimisation of an unlikely path, but conceptually it matches (eg)
> the page cache RCU-protected lookup.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>

Looks good,

Reviewed-by: Christoph Hellwig <hch@xxxxxx>