[PATCH v3 4/5] mm: add accounting for CMA pages and use them for watermark calculation

[Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx>]

From: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>

During watermark check we need to decrease available free pages number
by free CMA pages number because unmovable allocations cannot use pages
from CMA areas.

Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Cc: Michal Nazarewicz <mina86@xxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx>
Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
---
 mm/page_alloc.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5bb0cda..2166774 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1628,7 +1628,7 @@ static inline bool should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
  * of the allocation.
  */
 static bool __zone_watermark_ok(struct zone *z, int order, unsigned long mark,
-		      int classzone_idx, int alloc_flags, long free_pages)
+		      int classzone_idx, int alloc_flags, long free_pages, long free_cma_pages)
 {
 	/* free_pages my go negative - that's OK */
 	long min = mark;
@@ -1641,7 +1641,7 @@ static bool __zone_watermark_ok(struct zone *z, int order, unsigned long mark,
 	if (alloc_flags & ALLOC_HARDER)
 		min -= min / 4;
 
-	if (free_pages <= min + lowmem_reserve)
+	if (free_pages - free_cma_pages <= min + lowmem_reserve)
 		return false;
 	for (o = 0; o < order; o++) {
 		/* At the next order, this order's pages become unavailable */
@@ -1674,13 +1674,15 @@ bool zone_watermark_ok(struct zone *z, int order, unsigned long mark,
 		      int classzone_idx, int alloc_flags)
 {
 	return __zone_watermark_ok(z, order, mark, classzone_idx, alloc_flags,
-					zone_page_state(z, NR_FREE_PAGES));
+					zone_page_state(z, NR_FREE_PAGES),
+					zone_page_state(z, NR_FREE_CMA_PAGES));
 }
 
 bool zone_watermark_ok_safe(struct zone *z, int order, unsigned long mark,
 		      int classzone_idx, int alloc_flags)
 {
 	long free_pages = zone_page_state(z, NR_FREE_PAGES);
+	long free_cma_pages = zone_page_state(z, NR_FREE_CMA_PAGES);
 
 	if (z->percpu_drift_mark && free_pages < z->percpu_drift_mark)
 		free_pages = zone_page_state_snapshot(z, NR_FREE_PAGES);
@@ -1694,7 +1696,7 @@ bool zone_watermark_ok_safe(struct zone *z, int order, unsigned long mark,
 	 */
 	free_pages -= nr_zone_isolate_freepages(z);
 	return __zone_watermark_ok(z, order, mark, classzone_idx, alloc_flags,
-								free_pages);
+					free_pages, free_cma_pages);
 }
 
 #ifdef CONFIG_NUMA
-- 
1.7.11.3

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