[RFC 1/2] staging: ion: shrink page-pool by page unit

[Gioh Kim]

This patch shrink page-pool by page unit.

Signed-off-by: Gioh Kim <gioh.kim@xxxxxxx>
---
 drivers/staging/android/ion/ion_page_pool.c   |    5 +++--
 drivers/staging/android/ion/ion_system_heap.c |    7 +++++--
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/android/ion/ion_page_pool.c b/drivers/staging/android/ion/ion_page_pool.c
index 5864f3d..165152f 100644
--- a/drivers/staging/android/ion/ion_page_pool.c
+++ b/drivers/staging/android/ion/ion_page_pool.c
@@ -116,7 +116,7 @@ static int ion_page_pool_total(struct ion_page_pool *pool, bool high)
 int ion_page_pool_shrink(struct ion_page_pool *pool, gfp_t gfp_mask,
 				int nr_to_scan)
 {
-	int freed;
+	int freed = 0;
 	bool high;
 
 	if (current_is_kswapd())
@@ -127,7 +127,7 @@ int ion_page_pool_shrink(struct ion_page_pool *pool, gfp_t gfp_mask,
 	if (nr_to_scan == 0)
 		return ion_page_pool_total(pool, high);
 
-	for (freed = 0; freed < nr_to_scan; freed++) {
+	while (freed <= nr_to_scan) {
 		struct page *page;
 
 		mutex_lock(&pool->mutex);
@@ -141,6 +141,7 @@ int ion_page_pool_shrink(struct ion_page_pool *pool, gfp_t gfp_mask,
 		}
 		mutex_unlock(&pool->mutex);
 		ion_page_pool_free_pages(pool, page);
+		freed += (1 << pool->order);
 	}
 
 	return freed;
diff --git a/drivers/staging/android/ion/ion_system_heap.c b/drivers/staging/android/ion/ion_system_heap.c
index da2a63c..36e73c3 100644
--- a/drivers/staging/android/ion/ion_system_heap.c
+++ b/drivers/staging/android/ion/ion_system_heap.c
@@ -211,7 +211,7 @@ static int ion_system_heap_shrink(struct ion_heap *heap, gfp_t gfp_mask,
 					int nr_to_scan)
 {
 	struct ion_system_heap *sys_heap;
-	int nr_total = 0;
+	int nr_total = 0, nr_freed;
 	int i;
 
 	sys_heap = container_of(heap, struct ion_system_heap, heap);
@@ -219,7 +219,10 @@ static int ion_system_heap_shrink(struct ion_heap *heap, gfp_t gfp_mask,
 	for (i = 0; i < num_orders; i++) {
 		struct ion_page_pool *pool = sys_heap->pools[i];
 
-		nr_total += ion_page_pool_shrink(pool, gfp_mask, nr_to_scan);
+		nr_freed += ion_page_pool_shrink(pool, gfp_mask, nr_to_scan);
+		nr_total += nr_freed;
+		/* nr_to_scan can be negative */
+		nr_to_scan -= nr_freed;
 	}
 
 	return nr_total;
-- 
1.7.9.5

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