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

[Vlastimil Babka]

On 02/04/2016 10:30 AM, Vlastimil Babka wrote:
> On 02/04/2016 07:02 AM, Joonsoo Kim wrote:
>> On Wed, Feb 03, 2016 at 06:50:11PM +0100, Vlastimil Babka wrote:
>>> 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.
>>
>> You need to set CONFIG_COMPACTION or CONFIG_CMA to use
>> isolate_migratepages_range() and others in alloc_contig_range().
> 
> Hm, right, thanks for catching this. I admit I didn't try disabling
> compaction during the tests.

Here's a v2. Not the prettiest thing, admittedly.

----8<----
From: Vlastimil Babka <vbabka@xxxxxxx>
Date: Wed, 3 Feb 2016 17:45:26 +0100
Subject: [PATCH v2] mm, hugetlb: don't require CMA for runtime gigantic pages

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 and CONFIG_COMPACTION 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 and
CONFIG_COMPACTION enabled (or CONFIG_CMA as before). 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..4cb589ae6c4b 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
-
+#if (defined(CONFIG_MEMORY_ISOLATION) && defined(CONFIG_COMPACTION)) || defined(CONFIG_CMA)
 /* 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..50700ec80009 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_X86_64) && ((defined(CONFIG_MEMORY_ISOLATION) && defined(CONFIG_COMPACTION)) || defined(CONFIG_CMA))
 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..5fcfac52ca5a 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
+#if (defined(CONFIG_MEMORY_ISOLATION) && defined(CONFIG_COMPACTION)) || defined(CONFIG_CMA)
 
 static unsigned long pfn_max_align_down(unsigned long pfn)
 {
-- 
2.7.0