[PATCH] mm, hugetlb: don't require CMA for runtime gigantic pages

From: Vlastimil Babka
Date: Wed Feb 03 2016 - 12:50:33 EST


Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at
runtime") has added the runtime gigantic page allocation via
alloc_contig_range(), making this support available only when CONFIG_CMA is
enabled. Because it doesn't depend on MIGRATE_CMA pageblocks and the
associated infrastructure, it is possible with few simple adjustments to
require only CONFIG_MEMORY_ISOLATION instead of full CONFIG_CMA.

After this patch, alloc_contig_range() and related functions are available
and used for gigantic pages with just CONFIG_MEMORY_ISOLATION enabled. Note
CONFIG_CMA selects CONFIG_MEMORY_ISOLATION. This allows supporting runtime
gigantic pages without the CMA-specific checks in page allocator fastpaths.

Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Luiz Capitulino <lcapitulino@xxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Zhang Yanfei <zhangyanfei@xxxxxxxxxxxxxx>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
---
include/linux/gfp.h | 6 +++---
mm/hugetlb.c | 2 +-
mm/page_alloc.c | 2 +-
3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 8942af0813e3..752bb6259218 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -539,16 +539,16 @@ static inline bool pm_suspended_storage(void)
}
#endif /* CONFIG_PM_SLEEP */

-#ifdef CONFIG_CMA
-
+#ifdef CONFIG_MEMORY_ISOLATION
/* The below functions must be run on a range from a single zone. */
extern int alloc_contig_range(unsigned long start, unsigned long end,
unsigned migratetype);
extern void free_contig_range(unsigned long pfn, unsigned nr_pages);
+#endif

+#ifdef CONFIG_CMA
/* CMA stuff */
extern void init_cma_reserved_pageblock(struct page *page);
-
#endif

#endif /* __LINUX_GFP_H */
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index ef6963b577fd..66529a1c7929 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1002,7 +1002,7 @@ static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed)
((node = hstate_next_node_to_free(hs, mask)) || 1); \
nr_nodes--)

-#if defined(CONFIG_CMA) && defined(CONFIG_X86_64)
+#if defined(CONFIG_MEMORY_ISOLATION) && defined(CONFIG_X86_64)
static void destroy_compound_gigantic_page(struct page *page,
unsigned int order)
{
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 9d666df5ef95..29c530cdd7f4 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6599,7 +6599,7 @@ bool is_pageblock_removable_nolock(struct page *page)
return !has_unmovable_pages(zone, page, 0, true);
}

-#ifdef CONFIG_CMA
+#ifdef CONFIG_MEMORY_ISOLATION

static unsigned long pfn_max_align_down(unsigned long pfn)
{
--
2.7.0