Re: [PATCH v14 052/138] mm: Add folio_raw_mapping()

On Tue, Aug 10, 2021 at 09:42:13PM +0100, David Howells wrote:

Matthew Wilcox (Oracle) [off-list ref] wrote:

quoted

Convert __page_rmapping to folio_raw_mapping and move it to mm/internal.h.
It's only a couple of instructions (load and mask), so it's definitely
going to be cheaper to inline it than call it.  Leave page_rmapping
out of line.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

I assume you're going to call it from another source file at some point,
otherwise this is unnecessary.

Yes, it gets called from mm/ksm.c in a later patch in this series.
__page_rmapping() assumes it's being passed a head page and
folio_raw_mapping() asserts that.  Eventually, page_rmapping() can
go away (and maybe it should have been moved to folio-compat.c),
but I'm not inclined to do that now.

Apart from that,

Reviewed-by: David Howells <dhowells@redhat.com>