hi,
sorry to disturb, I will send another version to make a minor change
about page_lock checking in scan_movable_pages.
On 2017/1/25 11:25, Yisheng Xie wrote:
> We had considered all of the non-lru pages as unmovable before
> commit bda807d44454 ("mm: migrate: support non-lru movable page
> migration"). But now some of non-lru pages like zsmalloc,
> virtio-balloon pages also become movable. So we can offline such
> blocks by using non-lru page migration.
>
> This patch straightforwardly add non-lru migration code, which
> means adding non-lru related code to the functions which scan
> over pfn and collect pages to be migrated and isolate them before
> migration.
>
> Signed-off-by: Yisheng Xie <[email protected]>
> ---
> mm/memory_hotplug.c | 32 +++++++++++++++++++++-----------
> mm/page_alloc.c | 8 ++++++--
> 2 files changed, 27 insertions(+), 13 deletions(-)
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index e43142c1..fbdbffc 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1510,15 +1510,16 @@ int test_pages_in_a_zone(unsigned long start_pfn,
> unsigned long end_pfn)
> }
>
> /*
> - * Scan pfn range [start,end) to find movable/migratable pages (LRU pages
> - * and hugepages). We scan pfn because it's much easier than scanning over
> - * linked list. This function returns the pfn of the first found movable
> - * page if it's found, otherwise 0.
> + * Scan pfn range [start,end) to find movable/migratable pages (LRU pages,
> + * non-lru movable pages and hugepages). We scan pfn because it's much
> + * easier than scanning over linked list. This function returns the pfn
> + * of the first found movable page if it's found, otherwise 0.
> */
> static unsigned long scan_movable_pages(unsigned long start, unsigned long
> end)
> {
> unsigned long pfn;
> struct page *page;
> + bool movable;
> for (pfn = start; pfn < end; pfn++) {
> if (pfn_valid(pfn)) {
> page = pfn_to_page(pfn);
> @@ -1531,6 +1532,11 @@ static unsigned long scan_movable_pages(unsigned long
> start, unsigned long end)
> pfn = round_up(pfn + 1,
> 1 << compound_order(page)) - 1;
> }
> + lock_page(page);
> + movable = __PageMovable(page);
> + unlock_page(page);
> + if (movable)
> + return pfn;
> }
> }
> return 0;
> @@ -1600,21 +1606,25 @@ static struct page *new_node_page(struct page *page,
> unsigned long private,
> if (!get_page_unless_zero(page))
> continue;
> /*
> - * We can skip free pages. And we can only deal with pages on
> - * LRU.
> + * We can skip free pages. And we can deal with pages on
> + * LRU and non-lru movable pages.
> */
> - ret = isolate_lru_page(page);
> + if (PageLRU(page))
> + ret = isolate_lru_page(page);
> + else
> + ret = !isolate_movable_page(page, ISOLATE_UNEVICTABLE);
> if (!ret) { /* Success */
> put_page(page);
> list_add_tail(&page->lru, &source);
> move_pages--;
> - inc_node_page_state(page, NR_ISOLATED_ANON +
> - page_is_file_cache(page));
> + if (!__PageMovable(page))
> + inc_node_page_state(page, NR_ISOLATED_ANON +
> + page_is_file_cache(page));
>
> } else {
> #ifdef CONFIG_DEBUG_VM
> - pr_alert("removing pfn %lx from LRU failed\n", pfn);
> - dump_page(page, "failed to remove from LRU");
> + pr_alert("failed to isolate pfn %lx\n", pfn);
> + dump_page(page, "isolation failed");
> #endif
> put_page(page);
> /* Because we don't have big zone->lock. we should
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index d604d25..52d3067 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -7055,8 +7055,9 @@ void *__init alloc_large_system_hash(const char
> *tablename,
> * If @count is not zero, it is okay to include less @count unmovable pages
> *
> * PageLRU check without isolation or lru_lock could race so that
> - * MIGRATE_MOVABLE block might include unmovable pages. It means you can't
> - * expect this function should be exact.
> + * MIGRATE_MOVABLE block might include unmovable pages. And __PageMovable
> + * check without lock_page also may miss some movable non-lru pages at
> + * race condition. So you can't expect this function should be exact.
> */
> bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
> bool skip_hwpoisoned_pages)
> @@ -7112,6 +7113,9 @@ bool has_unmovable_pages(struct zone *zone, struct page
> *page, int count,
> if (skip_hwpoisoned_pages && PageHWPoison(page))
> continue;
>
> + if (__PageMovable(page))
> + continue;
> +
> if (!PageLRU(page))
> found++;
> /*
>
