Re: [PATCH 1/8] migrate: make core migration code aware of hugepage

[Wanpeng Li <liwanp@linux.vnet.ibm.com>]

On Thu, Jul 18, 2013 at 05:34:25PM -0400, Naoya Horiguchi wrote:
>Before enabling each user of page migration to support hugepage,
>this patch enables the list of pages for migration to link not only
>LRU pages, but also hugepages. As a result, putback_movable_pages()
>and migrate_pages() can handle both of LRU pages and hugepages.
>
>ChangeLog v3:
> - revert introducing migrate_movable_pages
> - add isolate_huge_page
>
>ChangeLog v2:
> - move code removing VM_HUGETLB from vma_migratable check into a
>   separate patch
> - hold hugetlb_lock in putback_active_hugepage
> - update comment near the definition of hugetlb_lock
>
>Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>

Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>

>---
> include/linux/hugetlb.h |  6 ++++++
> mm/hugetlb.c            | 32 +++++++++++++++++++++++++++++++-
> mm/migrate.c            | 10 +++++++++-
> 3 files changed, 46 insertions(+), 2 deletions(-)
>
>diff --git v3.11-rc1.orig/include/linux/hugetlb.h v3.11-rc1/include/linux/hugetlb.h
>index c2b1801..0b7a9e7 100644
>--- v3.11-rc1.orig/include/linux/hugetlb.h
>+++ v3.11-rc1/include/linux/hugetlb.h
>@@ -66,6 +66,9 @@ int hugetlb_reserve_pages(struct inode *inode, long from, long to,
> 						vm_flags_t vm_flags);
> void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed);
> int dequeue_hwpoisoned_huge_page(struct page *page);
>+bool isolate_huge_page(struct page *page, struct list_head *l);
>+void putback_active_hugepage(struct page *page);
>+void putback_active_hugepages(struct list_head *l);
> void copy_huge_page(struct page *dst, struct page *src);
>
> #ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
>@@ -134,6 +137,9 @@ static inline int dequeue_hwpoisoned_huge_page(struct page *page)
> 	return 0;
> }
>
>+#define isolate_huge_page(p, l) false
>+#define putback_active_hugepage(p)
>+#define putback_active_hugepages(l)
> static inline void copy_huge_page(struct page *dst, struct page *src)
> {
> }
>diff --git v3.11-rc1.orig/mm/hugetlb.c v3.11-rc1/mm/hugetlb.c
>index 83aff0a..4c48a70 100644
>--- v3.11-rc1.orig/mm/hugetlb.c
>+++ v3.11-rc1/mm/hugetlb.c
>@@ -48,7 +48,8 @@ static unsigned long __initdata default_hstate_max_huge_pages;
> static unsigned long __initdata default_hstate_size;
>
> /*
>- * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
>+ * Protects updates to hugepage_freelists, hugepage_activelist, nr_huge_pages,
>+ * free_huge_pages, and surplus_huge_pages.
>  */
> DEFINE_SPINLOCK(hugetlb_lock);
>
>@@ -3431,3 +3432,32 @@ int dequeue_hwpoisoned_huge_page(struct page *hpage)
> 	return ret;
> }
> #endif
>+
>+bool isolate_huge_page(struct page *page, struct list_head *l)
>+{
>+	VM_BUG_ON(!PageHead(page));
>+	if (!get_page_unless_zero(page))
>+		return false;
>+	spin_lock(&hugetlb_lock);
>+	list_move_tail(&page->lru, l);
>+	spin_unlock(&hugetlb_lock);
>+	return true;
>+}
>+
>+void putback_active_hugepage(struct page *page)
>+{
>+	VM_BUG_ON(!PageHead(page));
>+	spin_lock(&hugetlb_lock);
>+	list_move_tail(&page->lru, &(page_hstate(page))->hugepage_activelist);
>+	spin_unlock(&hugetlb_lock);
>+	put_page(page);
>+}
>+
>+void putback_active_hugepages(struct list_head *l)
>+{
>+	struct page *page;
>+	struct page *page2;
>+
>+	list_for_each_entry_safe(page, page2, l, lru)
>+		putback_active_hugepage(page);
>+}
>diff --git v3.11-rc1.orig/mm/migrate.c v3.11-rc1/mm/migrate.c
>index 6f0c244..b44a067 100644
>--- v3.11-rc1.orig/mm/migrate.c
>+++ v3.11-rc1/mm/migrate.c
>@@ -100,6 +100,10 @@ void putback_movable_pages(struct list_head *l)
> 	struct page *page2;
>
> 	list_for_each_entry_safe(page, page2, l, lru) {
>+		if (unlikely(PageHuge(page))) {
>+			putback_active_hugepage(page);
>+			continue;
>+		}
> 		list_del(&page->lru);
> 		dec_zone_page_state(page, NR_ISOLATED_ANON +
> 				page_is_file_cache(page));
>@@ -1025,7 +1029,11 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
> 		list_for_each_entry_safe(page, page2, from, lru) {
> 			cond_resched();
>
>-			rc = unmap_and_move(get_new_page, private,
>+			if (PageHuge(page))
>+				rc = unmap_and_move_huge_page(get_new_page,
>+						private, page, pass > 2, mode);
>+			else
>+				rc = unmap_and_move(get_new_page, private,
> 						page, pass > 2, mode);
>
> 			switch(rc) {
>-- 
>1.8.3.1
>
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