cma: fix watermark checking

* Add ALLOC_CMA alloc flag and pass it to [__]zone_watermark_ok()
  (from Minchan Kim).

* During watermark check decrease available free pages number by
  free CMA pages number if necessary (unmovable allocations cannot
  use pages from CMA areas).

Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/compaction.c

@@ -934,6 +934,7 @@ unsigned long try_to_compact_pages(struct zonelist *zonelist,
 	struct zoneref *z;
 	struct zone *zone;
 	int rc = COMPACT_SKIPPED;
+	int alloc_flags = 0;
 
 	/* Check if the GFP flags allow compaction */
 	if (!order || !may_enter_fs || !may_perform_io)
@@ -941,6 +942,10 @@ unsigned long try_to_compact_pages(struct zonelist *zonelist,
 
 	count_vm_event(COMPACTSTALL);
 
+#ifdef CONFIG_CMA
+	if (allocflags_to_migratetype(gfp_mask) == MIGRATE_MOVABLE)
+		alloc_flags |= ALLOC_CMA;
+#endif
 	/* Compact each zone in the list */
 	for_each_zone_zonelist_nodemask(zone, z, zonelist, high_zoneidx,
 								nodemask) {
@@ -951,7 +956,8 @@ unsigned long try_to_compact_pages(struct zonelist *zonelist,
 		rc = max(status, rc);
 
 		/* If a normal allocation would succeed, stop compacting */
-		if (zone_watermark_ok(zone, order, low_wmark_pages(zone), 0, 0))
+		if (zone_watermark_ok(zone, order, low_wmark_pages(zone), 0,
+				      alloc_flags))
 			break;
 	}
 

mm/internal.h

@@ -358,4 +358,18 @@ extern unsigned long vm_mmap_pgoff(struct file *, unsigned long,
 extern void set_pageblock_order(void);
 unsigned long reclaim_clean_pages_from_list(struct zone *zone,
 					    struct list_head *page_list);
+/* The ALLOC_WMARK bits are used as an index to zone->watermark */
+#define ALLOC_WMARK_MIN		WMARK_MIN
+#define ALLOC_WMARK_LOW		WMARK_LOW
+#define ALLOC_WMARK_HIGH	WMARK_HIGH
+#define ALLOC_NO_WATERMARKS	0x04 /* don't check watermarks at all */
+
+/* Mask to get the watermark bits */
+#define ALLOC_WMARK_MASK	(ALLOC_NO_WATERMARKS-1)
+
+#define ALLOC_HARDER		0x10 /* try to alloc harder */
+#define ALLOC_HIGH		0x20 /* __GFP_HIGH set */
+#define ALLOC_CPUSET		0x40 /* check for correct cpuset */
+#define ALLOC_CMA		0x80 /* allow allocations from CMA areas */
+
 #endif	/* __MM_INTERNAL_H */

mm/page_alloc.c

@@ -1541,19 +1541,6 @@ struct page *buffered_rmqueue(struct zone *preferred_zone,
 	return NULL;
 }
 
-/* The ALLOC_WMARK bits are used as an index to zone->watermark */
-#define ALLOC_WMARK_MIN		WMARK_MIN
-#define ALLOC_WMARK_LOW		WMARK_LOW
-#define ALLOC_WMARK_HIGH	WMARK_HIGH
-#define ALLOC_NO_WATERMARKS	0x04 /* don't check watermarks at all */
-
-/* Mask to get the watermark bits */
-#define ALLOC_WMARK_MASK	(ALLOC_NO_WATERMARKS-1)
-
-#define ALLOC_HARDER		0x10 /* try to alloc harder */
-#define ALLOC_HIGH		0x20 /* __GFP_HIGH set */
-#define ALLOC_CPUSET		0x40 /* check for correct cpuset */
-
 #ifdef CONFIG_FAIL_PAGE_ALLOC
 
 static struct {
@@ -1648,7 +1635,11 @@ static bool __zone_watermark_ok(struct zone *z, int order, unsigned long mark,
 		min -= min / 2;
 	if (alloc_flags & ALLOC_HARDER)
 		min -= min / 4;
-
+#ifdef CONFIG_CMA
+	/* If allocation can't use CMA areas don't use free CMA pages */
+	if (!(alloc_flags & ALLOC_CMA))
+		free_pages -= zone_page_state(z, NR_FREE_CMA_PAGES);
+#endif
 	if (free_pages <= min + lowmem_reserve)
 		return false;
 	for (o = 0; o < order; o++) {
@@ -2362,7 +2353,10 @@ gfp_to_alloc_flags(gfp_t gfp_mask)
 				 unlikely(test_thread_flag(TIF_MEMDIE))))
 			alloc_flags |= ALLOC_NO_WATERMARKS;
 	}
-
+#ifdef CONFIG_CMA
+	if (allocflags_to_migratetype(gfp_mask) == MIGRATE_MOVABLE)
+		alloc_flags |= ALLOC_CMA;
+#endif
 	return alloc_flags;
 }
 
@@ -2587,6 +2581,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
 	struct page *page = NULL;
 	int migratetype = allocflags_to_migratetype(gfp_mask);
 	unsigned int cpuset_mems_cookie;
+	int alloc_flags = ALLOC_WMARK_LOW|ALLOC_CPUSET;
 
 	gfp_mask &= gfp_allowed_mask;
 
@@ -2615,9 +2610,13 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
 	if (!preferred_zone)
 		goto out;
 
+#ifdef CONFIG_CMA
+	if (allocflags_to_migratetype(gfp_mask) == MIGRATE_MOVABLE)
+		alloc_flags |= ALLOC_CMA;
+#endif
 	/* First allocation attempt */
 	page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, nodemask, order,
-			zonelist, high_zoneidx, ALLOC_WMARK_LOW|ALLOC_CPUSET,
+			zonelist, high_zoneidx, alloc_flags,
 			preferred_zone, migratetype);
 	if (unlikely(!page))
 		page = __alloc_pages_slowpath(gfp_mask, order,