Re: [PATCH v1 1/4] mm/compaction: enable compacting >0 order folios.

[Matthew Wilcox]

On Mon, Nov 13, 2023 at 12:01:54PM -0500, Zi Yan wrote:
> +	/* this makes migrate_pages() split the source page and retry */
> +	if (folio_order(src) > 0)
> +		return NULL;

Nit: folio_test_large() is more efficient than folio_order() > 0.
The former simply tests the bit, while the second tests the bit, then
loads folio->_order to check it's >0.  We know it will be, but there's
no way to tell gcc that if the bit is set, this value is definitely not 0.