[PATCH v2 10/18] zsmalloc: factor page chain functionality out

Minchan Kim
2016-03-21T06:31:31Z

For migration, we need to create sub-page chain of zspage
dynamically so this patch factors it out from alloc_zspage.

As a minor refactoring, it makes OBJ_ALLOCATED_TAG assign
more clear in obj_malloc(it could be another patch but it's
trivial so I want to put together in this patch).

Signed-off-by: Minchan Kim <minchan@kernel.org>
---
mm/zsmalloc.c | 80 ++++++++++++++++++++++++++++++++++-------------------------
1 file changed, 46 insertions(+), 34 deletions(-)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 958f27a9079d..833da8f4ffc9 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -982,7 +982,9 @@ 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;
+ INIT_LIST_HEAD(&first_page->lru);
+ set_zspage_inuse(first_page, 0);

while (page) {
struct page *next_page;
@@ -1027,13 +1029,44 @@ static void init_zspage(struct size_class *class, struct page *first_page)
set_freeobj(first_page, 0);
}

+static void create_page_chain(struct page *pages[], int nr_pages)
+{
+ int i;
+ struct page *page;
+ struct page *prev_page = NULL;
+ struct page *first_page = NULL;
+
+ for (i = 0; i < nr_pages; i++) {
+ page = pages[i];
+
+ INIT_LIST_HEAD(&page->lru);
+ if (i == 0) {
+ SetPagePrivate(page);
+ set_page_private(page, 0);
+ first_page = page;
+ }
+
+ if (i == 1)
+ set_page_private(first_page, (unsigned long)page);
+ if (i >= 1)
+ set_page_private(page, (unsigned long)first_page);
+ if (i >= 2)
+ list_add(&page->lru, &prev_page->lru);
+ if (i == nr_pages - 1)
+ SetPagePrivate2(page);
+
+ prev_page = page;
+ }
+}
+
/*
* Allocate a zspage for the given size class
*/
static struct page *alloc_zspage(struct size_class *class, gfp_t flags)
{
- int i, error;
- struct page *first_page = NULL, *uninitialized_var(prev_page);
+ int i;
+ struct page *first_page = NULL;
+ struct page *pages[ZS_MAX_PAGES_PER_ZSPAGE];

/*
* Allocate individual pages and link them together as:
@@ -1046,43 +1079,23 @@ 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;
-
- INIT_LIST_HEAD(&page->lru);
- if (i == 0) { /* first page */
- page->freelist = NULL;
- SetPagePrivate(page);
- set_page_private(page, 0);
- first_page = page;
- set_zspage_inuse(page, 0);
+ if (!page) {
+ while (--i >= 0)
+ __free_page(pages[i]);
+ return NULL;
}
- if (i == 1)
- set_page_private(first_page, (unsigned long)page);
- if (i >= 1)
- 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 */
- SetPagePrivate2(page);
- prev_page = page;
+
+ pages[i] = page;
}

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

- error = 0; /* Success */
-
-cleanup:
- if (unlikely(error) && first_page) {
- free_zspage(first_page);
- first_page = NULL;
- }
-
return first_page;
}

@@ -1422,7 +1435,6 @@ static unsigned long obj_malloc(struct size_class *class,
unsigned long m_offset;
void *vaddr;

- handle |= OBJ_ALLOCATED_TAG;
obj = get_freeobj(first_page);
objidx_to_page_and_offset(class, first_page, obj,
&m_page, &m_offset);
@@ -1432,10 +1444,10 @@ static unsigned long obj_malloc(struct size_class *class,
set_freeobj(first_page, link->next >> OBJ_ALLOCATED_TAG);
if (!class->huge)
/* record handle in the header of allocated chunk */
- link->handle = handle;
+ link->handle = handle | OBJ_ALLOCATED_TAG;
else
/* record handle in first_page->private */
- set_page_private(first_page, handle);
+ set_page_private(first_page, handle | OBJ_ALLOCATED_TAG);
kunmap_atomic(vaddr);
mod_zspage_inuse(first_page, 1);
zs_stat_inc(class, OBJ_USED, 1);
--
1.9.1