diff mbox series

[v6,04/51] mm: Move PageDoubleMap bit

Message ID 20200610201345.13273-5-willy@infradead.org (mailing list archive)
State New, archived
Headers show
Series Large pages in the page cache | expand

Commit Message

Matthew Wilcox June 10, 2020, 8:12 p.m. UTC 
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

PG_private_2 is defined as being PF_ANY (applicable to tail pages
as well as regular & head pages).  That means that the first tail
page of a double-map page will appear to have Private2 set.  Use the
Workingset bit instead which is defined as PF_HEAD so any attempt to
access the Workingset bit on a tail page will redirect to the head page's
Workingset bit.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/page-flags.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Zi Yan June 11, 2020, 3:03 p.m. UTC | #1 
On 10 Jun 2020, at 16:12, Matthew Wilcox wrote:

> From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
>
> PG_private_2 is defined as being PF_ANY (applicable to tail pages
> as well as regular & head pages).  That means that the first tail
> page of a double-map page will appear to have Private2 set.  Use the
> Workingset bit instead which is defined as PF_HEAD so any attempt to
> access the Workingset bit on a tail page will redirect to the head page's
> Workingset bit.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---

Make sense to me.

Reviewed-by: Zi Yan <ziy@nvidia.com>

—
Best Regards,
Yan Zi
diff mbox series

Patch

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 222f6f7b2bb3..de6e0696f55c 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -164,7 +164,7 @@  enum pageflags {
 	PG_slob_free = PG_private,
 
 	/* Compound pages. Stored in first tail page's flags */
-	PG_double_map = PG_private_2,
+	PG_double_map = PG_workingset,
 
 	/* non-lru isolated movable page */
 	PG_isolated = PG_reclaim,