[PATCH] mm: cma: hack/workaround for some allocation issues

[Marek Szyprowski]

This is a quick and dirty patch and hack to solve some memory allocation
issues that appeared at CMA v17 after switching migration code from
hotplug to memory compaction. Especially the issue with watermark
adjustment need a real fix instead of disabling the code.

Signed-off-by: Marek Szyprowski <m.szyprowski at samsung.com>
---

Hello,

This patch fixes the issues that have been reported recently. It should
be considered only as a temporary solution until a new version of CMA
patches is ready.

Best regards
--
Marek Szyprowski
Samsung Poland R&D Center

---
 mm/compaction.c |    5 ++++-
 mm/page_alloc.c |   12 +++++++++---
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index 3e07341..41976f8 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -79,8 +79,9 @@ isolate_freepages_range(struct zone *zone,
 skip:
 			if (freelist)
 				goto next;
+failed:
 			for (; start < pfn; ++start)
-				__free_page(pfn_to_page(pfn));
+				__free_page(pfn_to_page(start));
 			return 0;
 		}
 
@@ -91,6 +92,8 @@ skip:
 			struct page *p = page;
 			for (i = isolated; i; --i, ++p)
 				list_add(&p->lru, freelist);
+		} else if (!isolated) {
+			goto failed;
 		}
 
 next:
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 714b1c1..b4a46c7 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1303,12 +1303,12 @@ int split_free_page(struct page *page)
 
 	zone = page_zone(page);
 	order = page_order(page);
-
+#if 0
 	/* Obey watermarks as if the page was being allocated */
 	watermark = low_wmark_pages(zone) + (1 << order);
 	if (!zone_watermark_ok(zone, 0, watermark, 0, 0))
 		return 0;
-
+#endif
 	/* Remove page from free list */
 	list_del(&page->lru);
 	zone->free_area[order].nr_free--;
@@ -5734,6 +5734,12 @@ static unsigned long pfn_align_to_maxpage_up(unsigned long pfn)
 	return ALIGN(pfn, MAX_ORDER_NR_PAGES);
 }
 
+static struct page *
+cma_migrate_alloc(struct page *page, unsigned long private, int **x)
+{
+	return alloc_page(GFP_HIGHUSER_MOVABLE);
+}
+
 static int __alloc_contig_migrate_range(unsigned long start, unsigned long end)
 {
 	/* This function is based on compact_zone() from compaction.c. */
@@ -5801,7 +5807,7 @@ static int __alloc_contig_migrate_range(unsigned long start, unsigned long end)
 		}
 
 		/* Try to migrate. */
-		ret = migrate_pages(&cc.migratepages, compaction_alloc,
+		ret = migrate_pages(&cc.migratepages, cma_migrate_alloc,
 				    (unsigned long)&cc, false, cc.sync);
 
 		/* Migrated all of them? Great! */
-- 
1.7.1.569.g6f426