The patch titled
Subject: zsmalloc: keep first object offset in struct page
has been added to the -mm tree. Its filename is
zsmalloc-page-migration-support-fix-2.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/zsmalloc-page-migration-support-fix-2.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/zsmalloc-page-migration-support-fix-2.patch
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------------------------------------------------------
From: Minchan Kim <minchan@xxxxxxxxxx>
Subject: zsmalloc: keep first object offset in struct page
In early draft of zspage migration, we couldn't use page._mapcount because
it was used for storing movable flag so we added runtime calculation to
get first object offset in a page but it causes rather many instruction
and even bug.
Since then, we don't use page._mapcount as page flag any more so now
there is no problem to use the field to store first object offset.
Link: http://lkml.kernel.org/r/1465788015-23195-1-git-send-email-minchan@xxxxxxxxxx
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/zsmalloc.c | 44 ++++++++++++++++----------------------------
1 file changed, 16 insertions(+), 28 deletions(-)
diff -puN mm/zsmalloc.c~zsmalloc-page-migration-support-fix-2 mm/zsmalloc.c
--- a/mm/zsmalloc.c~zsmalloc-page-migration-support-fix-2
+++ a/mm/zsmalloc.c
@@ -509,6 +509,16 @@ static inline struct page *get_first_pag
return first_page;
}
+static inline int get_first_obj_offset(struct page *page)
+{
+ return page->units;
+}
+
+static inline void set_first_obj_offset(struct page *page, int offset)
+{
+ page->units = offset;
+}
+
static inline unsigned int get_freeobj(struct zspage *zspage)
{
return zspage->freeobj;
@@ -869,31 +879,6 @@ static struct page *get_next_page(struct
return page->freelist;
}
-/* Get byte offset of first object in the @page */
-static int get_first_obj_offset(struct size_class *class,
- struct page *first_page, struct page *page)
-{
- int pos;
- int page_idx = 0;
- int ofs = 0;
- struct page *cursor = first_page;
-
- if (first_page == page)
- goto out;
-
- while (page != cursor) {
- page_idx++;
- cursor = get_next_page(cursor);
- }
-
- pos = class->objs_per_zspage * class->size *
- page_idx / class->pages_per_zspage;
-
- ofs = (pos + class->size) % PAGE_SIZE;
-out:
- return ofs;
-}
-
/**
* obj_to_location - get (<page>, <obj_idx>) from encoded object value
* @page: page object resides in zspage
@@ -963,6 +948,7 @@ static void reset_page(struct page *page
clear_bit(PG_private, &page->flags);
clear_bit(PG_private_2, &page->flags);
set_page_private(page, 0);
+ page_mapcount_reset(page);
ClearPageHugeObject(page);
page->freelist = NULL;
}
@@ -1060,6 +1046,8 @@ static void init_zspage(struct size_clas
struct link_free *link;
void *vaddr;
+ set_first_obj_offset(page, off);
+
vaddr = kmap_atomic(page);
link = (struct link_free *)vaddr + off / sizeof(*link);
@@ -1754,9 +1742,8 @@ static unsigned long find_alloced_obj(st
int offset = 0;
unsigned long handle = 0;
void *addr = kmap_atomic(page);
- struct zspage *zspage = get_zspage(page);
- offset = get_first_obj_offset(class, get_first_page(zspage), page);
+ offset = get_first_obj_offset(page);
offset += class->size * index;
while (offset < PAGE_SIZE) {
@@ -1968,6 +1955,7 @@ static void replace_sub_page(struct size
} while ((page = get_next_page(page)) != NULL);
create_page_chain(class, zspage, pages);
+ set_first_obj_offset(newpage, get_first_obj_offset(oldpage));
if (unlikely(PageHugeObject(oldpage)))
newpage->index = oldpage->index;
__SetPageMovable(newpage, page_mapping(oldpage));
@@ -2054,7 +2042,7 @@ int zs_page_migrate(struct address_space
get_zspage_mapping(zspage, &class_idx, &fullness);
pool = mapping->private_data;
class = pool->size_class[class_idx];
- offset = get_first_obj_offset(class, get_first_page(zspage), page);
+ offset = get_first_obj_offset(page);
spin_lock(&class->lock);
if (!get_zspage_inuse(zspage)) {
_
Patches currently in -mm which might be from minchan@xxxxxxxxxx are
mm-use-put_page-to-free-page-instead-of-putback_lru_page.patch
mm-migrate-support-non-lru-movable-page-migration.patch
mm-balloon-use-general-non-lru-movable-page-feature.patch
zsmalloc-keep-max_object-in-size_class.patch
zsmalloc-use-bit_spin_lock.patch
zsmalloc-use-accessor.patch
zsmalloc-factor-page-chain-functionality-out.patch
zsmalloc-introduce-zspage-structure.patch
zsmalloc-separate-free_zspage-from-putback_zspage.patch
zsmalloc-use-freeobj-for-index.patch
zsmalloc-page-migration-support.patch
zsmalloc-page-migration-support-fix.patch
zsmalloc-page-migration-support-fix-2.patch
zram-use-__gfp_movable-for-memory-allocation.patch
zsmalloc-use-obj_tag_bit-for-bit-shifter.patch
mm-add-nr_zsmalloc-to-vmstat.patch
mm-add-nr_zsmalloc-to-vmstat-fix-2.patch
mm-fix-build-warnings-in-linux-compactionh.patch
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