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Date: Sat, 12 Mar 2016 11:09:36 +0800
From: xuyiping <xuyiping@...ilicon.com>
To: Minchan Kim <minchan@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>
CC: <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
<jlayton@...chiereds.net>, <bfields@...ldses.org>,
Vlastimil Babka <vbabka@...e.cz>,
Joonsoo Kim <iamjoonsoo.kim@....com>, <koct9i@...il.com>,
<aquini@...hat.com>, <virtualization@...ts.linux-foundation.org>,
Mel Gorman <mgorman@...e.de>, Hugh Dickins <hughd@...gle.com>,
Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
<rknize@...orola.com>, Rik van Riel <riel@...hat.com>,
Gioh Kim <gurugio@...mail.net>
Subject: Re: [PATCH v1 13/19] zsmalloc: factor page chain functionality out
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@...nel.org>
> ---
> 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.
> * (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;
> }
>
> @@ -1419,7 +1432,6 @@ 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_ofs(class, first_page, obj,
> &m_page, &m_offset);
> @@ -1429,10 +1441,10 @@ 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);
>
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