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Commit 22c5cef1 authored by Yisheng Xie's avatar Yisheng Xie Committed by Linus Torvalds
Browse files

mm/zsmalloc: remove redundant SetPagePrivate2 in create_page_chain 

We had used page->lru to link the component pages (except the first
page) of a zspage, and used INIT_LIST_HEAD(&page->lru) to init it.
Therefore, to get the last page's next page, which is NULL, we had to
use page flag PG_Private_2 to identify it.

But now, we use page->freelist to link all of the pages in zspage and
init the page->freelist as NULL for last page, so no need to use
PG_Private_2 anymore.

This remove redundant SetPagePrivate2 in create_page_chain and
ClearPagePrivate2 in reset_page().  Save a few cycles for migration of
zsmalloc page :)

Link: http://lkml.kernel.org/r/1487076509-49270-1-git-send-email-xieyisheng1@huawei.com


Signed-off-by: default avatarYisheng Xie <xieyisheng1@huawei.com>
Reviewed-by: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: default avatarMinchan Kim <minchan@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e1587a49

mm/zsmalloc.c

+1 −5
Original line number Diff line number Diff line
@@ -24,7 +24,6 @@ 
 *

 * Usage of struct page flags:

 *	PG_private: identifies the first component page

 *	PG_private2: identifies the last component page

 *	PG_owner_priv_1: identifies the huge component page

 *

 */
@@ -938,7 +937,6 @@ static void reset_page(struct page *page) 
{

	__ClearPageMovable(page);

	ClearPagePrivate(page);

	ClearPagePrivate2(page);

	set_page_private(page, 0);

	page_mapcount_reset(page);

	ClearPageHugeObject(page);
@@ -1085,7 +1083,7 @@ static void create_page_chain(struct size_class *class, struct zspage *zspage, 
	 * 2. each sub-page point to zspage using page->private

	 *

	 * we set PG_private to identify the first page (i.e. no other sub-page

	 * has this flag set) and PG_private_2 to identify the last page.

	 * has this flag set).

	 */

	for (i = 0; i < nr_pages; i++) {

		page = pages[i];
@@ -1100,8 +1098,6 @@ static void create_page_chain(struct size_class *class, struct zspage *zspage, 
		} else {

			prev_page->freelist = page;

		}

		if (i == nr_pages - 1)

			SetPagePrivate2(page);

		prev_page = page;

	}

}