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Subject[PATCH v5 07/12] zsmalloc: factor page chain functionality out
Date
For page migration, we need to create page chain of zspage dynamically
so this patch factors it out from alloc_zspage.

Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
mm/zsmalloc.c | 59 +++++++++++++++++++++++++++++++++++------------------------
1 file changed, 35 insertions(+), 24 deletions(-)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 086fd65311f7..1855e75766c7 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -959,7 +959,8 @@ static void init_zspage(struct size_class *class, struct page *first_page)
unsigned long off = 0;
struct page *page = first_page;

- VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
+ first_page->freelist = NULL;
+ set_zspage_inuse(first_page, 0);

while (page) {
struct page *next_page;
@@ -995,15 +996,16 @@ static void init_zspage(struct size_class *class, struct page *first_page)
page = next_page;
off %= PAGE_SIZE;
}
+
+ set_freeobj(first_page, (unsigned long)location_to_obj(first_page, 0));
}

-/*
- * Allocate a zspage for the given size class
- */
-static struct page *alloc_zspage(struct size_class *class, gfp_t flags)
+static void create_page_chain(struct page *pages[], int nr_pages)
{
- int i, error;
- struct page *first_page = NULL, *uninitialized_var(prev_page);
+ int i;
+ struct page *page;
+ struct page *prev_page = NULL;
+ struct page *first_page = NULL;

/*
* Allocate individual pages and link them together as:
@@ -1016,20 +1018,14 @@ static struct page *alloc_zspage(struct size_class *class, gfp_t flags)
* (i.e. no other sub-page has this flag set) and PG_private_2 to
* identify the last page.
*/
- error = -ENOMEM;
- for (i = 0; i < class->pages_per_zspage; i++) {
- struct page *page;
-
- page = alloc_page(flags);
- if (!page)
- goto cleanup;
+ for (i = 0; i < nr_pages; i++) {
+ page = pages[i];

INIT_LIST_HEAD(&page->lru);
- if (i == 0) { /* first page */
+ if (i == 0) {
SetPagePrivate(page);
set_page_private(page, 0);
first_page = page;
- set_zspage_inuse(first_page, 0);
}
if (i == 1)
set_page_private(first_page, (unsigned long)page);
@@ -1037,22 +1033,37 @@ static struct page *alloc_zspage(struct size_class *class, gfp_t flags)
set_page_private(page, (unsigned long)first_page);
if (i >= 2)
list_add(&page->lru, &prev_page->lru);
- if (i == class->pages_per_zspage - 1) /* last page */
+ if (i == nr_pages - 1)
SetPagePrivate2(page);
prev_page = page;
}
+}

- init_zspage(class, first_page);
+/*
+ * Allocate a zspage for the given size class
+ */
+static struct page *alloc_zspage(struct size_class *class, gfp_t flags)
+{
+ int i;
+ struct page *first_page = NULL;
+ struct page *pages[ZS_MAX_PAGES_PER_ZSPAGE];

- set_freeobj(first_page, (unsigned long)location_to_obj(first_page, 0));
- error = 0; /* Success */
+ for (i = 0; i < class->pages_per_zspage; i++) {
+ struct page *page;

-cleanup:
- if (unlikely(error) && first_page) {
- free_zspage(first_page);
- first_page = NULL;
+ page = alloc_page(flags);
+ if (!page) {
+ while (--i >= 0)
+ __free_page(pages[i]);
+ return NULL;
+ }
+ pages[i] = page;
}

+ create_page_chain(pages, class->pages_per_zspage);
+ first_page = pages[0];
+ init_zspage(class, first_page);
+
return first_page;
}

--
1.9.1
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