On Sat, Mar 12, 2016 at 11:09:36AM +0800, xuyiping wrote:
>
>
> On 2016/3/11 15:30, Minchan Kim wrote:
> >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@xxxxxxxxxx>
> >---
> > mm/zsmalloc.c | 78 ++++++++++++++++++++++++++++++++++-------------------------
> > 1 file changed, 45 insertions(+), 33 deletions(-)
> >
> >diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> >index bfc6a048afac..f86f8aaeb902 100644
> >--- a/mm/zsmalloc.c
> >+++ b/mm/zsmalloc.c
> >@@ -977,7 +977,9 @@ 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;
> >@@ -1022,13 +1024,44 @@ 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;
> >+ int i;
> > struct page *first_page = NULL, *uninitialized_var(prev_page);
> >+ struct page *pages[ZS_MAX_PAGES_PER_ZSPAGE];
> >
> > /*
> > * Allocate individual pages and link them together as:
> >@@ -1041,43 +1074,23 @@ static struct page *alloc_zspage(struct size_class *class, gfp_t flags)
>
> *uninitialized_var(prev_page) in alloc_zspage is not in use more.
True.
It says why we should avoid uninitialized_var if possible.
If we didn't use uninitialized_var, compiler could warn about it
when I did build test.
Thanks.
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