[PATCH 2/2] mm: Make alloc_contig_range handle in-use hugetlb pages

[Oscar Salvador]

In-use hugetlb pages can be migrated as any other page (LRU
and Movable), so let alloc_contig_range handle them.

All we need is to succesfully isolate such page.

Signed-off-by: Oscar Salvador <osalva...@suse.de>
---
 include/linux/hugetlb.h |  5 +++--
 mm/compaction.c         | 11 ++++++++++-
 mm/hugetlb.c            |  6 ++++--
 mm/vmscan.c             |  5 +++--
 4 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 72352d718829..8c17d0dbc87c 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -505,7 +505,7 @@ struct huge_bootmem_page {
        struct hstate *hstate;
 };
 
-bool isolate_or_dissolve_huge_page(struct page *page);
+bool isolate_or_dissolve_huge_page(struct page *page, struct list_head *list);
 struct page *alloc_huge_page(struct vm_area_struct *vma,
                                unsigned long addr, int avoid_reserve);
 struct page *alloc_huge_page_nodemask(struct hstate *h, int preferred_nid,
@@ -776,7 +776,8 @@ void set_page_huge_active(struct page *page);
 #else  /* CONFIG_HUGETLB_PAGE */
 struct hstate {};
 
-static inline bool isolate_or_dissolve_huge_page(struct page *page)
+static inline bool isolate_or_dissolve_huge_page(struct page *page,
+                                                struct list_head *list)
 {
        return false;
 }
diff --git a/mm/compaction.c b/mm/compaction.c
index d52506ed9db7..55a41a9228a9 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -906,9 +906,17 @@ isolate_migratepages_block(struct compact_control *cc, 
unsigned long low_pfn,
                }
 
                if (PageHuge(page) && cc->alloc_contig) {
-                       if (!isolate_or_dissolve_huge_page(page))
+                       if (!isolate_or_dissolve_huge_page(page, 
&cc->migratepages))
                                goto isolate_fail;
 
+                       if (PageHuge(page)) {
+                               /*
+                                * Hugepage was succesfully isolated.
+                                */
+                               low_pfn += compound_nr(page) - 1;
+                               goto isolate_success_no_list;
+                       }
+
                        /*
                         * Ok, the hugepage was dissolved. Now these pages are
                         * Buddy and cannot be re-allocated because they are
@@ -1053,6 +1061,7 @@ isolate_migratepages_block(struct compact_control *cc, 
unsigned long low_pfn,
 
 isolate_success:
                list_add(&page->lru, &cc->migratepages);
+isolate_success_no_list:
                cc->nr_migratepages += compound_nr(page);
                nr_isolated += compound_nr(page);
 
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index b78926bca60a..9fa678d13c68 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2351,7 +2351,7 @@ static bool alloc_and_dissolve_huge_page(struct hstate 
*h, struct page *page)
        return ret;
 }
 
-bool isolate_or_dissolve_huge_page(struct page *page)
+bool isolate_or_dissolve_huge_page(struct page *page, struct list_head *list)
 {
        struct hstate *h = NULL;
        struct page *head;
@@ -2379,7 +2379,9 @@ bool isolate_or_dissolve_huge_page(struct page *page)
                 */
                return ret;
 
-       if(!page_count(head) && alloc_and_dissolve_huge_page(h, head))
+       if (page_count(head) && isolate_huge_page(head, list))
+               ret = true;
+       else if(!page_count(head) && alloc_and_dissolve_huge_page(h, head))
                ret = true;
 
        return ret;
diff --git a/mm/vmscan.c b/mm/vmscan.c
index b1b574ad199d..0803adca4469 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1506,8 +1506,9 @@ unsigned int reclaim_clean_pages_from_list(struct zone 
*zone,
        LIST_HEAD(clean_pages);
 
        list_for_each_entry_safe(page, next, page_list, lru) {
-               if (page_is_file_lru(page) && !PageDirty(page) &&
-                   !__PageMovable(page) && !PageUnevictable(page)) {
+               if (!PageHuge(page) && page_is_file_lru(page) &&
+                   !PageDirty(page) && !__PageMovable(page) &&
+                   !PageUnevictable(page)) {
                        ClearPageActive(page);
                        list_move(&page->lru, &clean_pages);
                }
-- 
2.16.3