[PATCH 3/3] dma-pool: limit DMA and DMA32 zone size pools

[Christoph Hellwig]

Limit the sizing of the atomic pools for allocations from
ZONE_DMA and ZONE_DMA32 based on the number of pages actually
present in those zones instead of the total memory.

Fixes: c84dc6e68a1d ("dma-pool: add additional coherent pools to map to gfp mask")
Reported-by: Michal Hocko <mhocko@xxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 kernel/dma/pool.c | 40 +++++++++++++++++++++++++++++-----------
 1 file changed, 29 insertions(+), 11 deletions(-)

diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c
index 5b07b0379a501..f629c6dfd8555 100644
--- a/kernel/dma/pool.c
+++ b/kernel/dma/pool.c
@@ -193,28 +193,46 @@ static unsigned long calculate_pool_size(unsigned long zone_pages)
 	return max_t(unsigned long, nr_pages << PAGE_SHIFT, SZ_128K);
 }
 
+#if defined(CONFIG_ZONE_DMA) || defined(CONFIG_ZONE_DMA32)
+static unsigned long __init nr_managed_pages(int zone_idx)
+{
+	struct pglist_data *pgdat;
+	unsigned long nr_pages = 0;
+
+	for_each_online_pgdat(pgdat)
+		nr_pages += zone_managed_pages(&pgdat->node_zones[zone_idx]);
+	return nr_pages;
+}
+#endif /* CONFIG_ZONE_DMA || CONFIG_ZONE_DMA32 */
+
 static int __init dma_atomic_pool_init(void)
 {
+	unsigned long nr_zone_dma_pages, nr_zone_dma32_pages;
+
+#ifdef CONFIG_ZONE_DMA
+	nr_zone_dma_pages = nr_managed_pages(ZONE_DMA);
+	if (nr_zone_dma_pages)
+		atomic_pool_dma = __dma_atomic_pool_init(
+				calculate_pool_size(nr_zone_dma_pages),
+				GFP_DMA);
+#endif
+#ifdef CONFIG_ZONE_DMA32
+	nr_zone_dma32_pages = nr_managed_pages(ZONE_DMA32);
+	if (nr_zone_dma32_pages)
+		atomic_pool_dma32 = __dma_atomic_pool_init(
+				calculate_pool_size(nr_zone_dma32_pages),
+				GFP_DMA32);
+#endif
 	/*
 	 * If coherent_pool was not used on the command line, default the pool
 	 * sizes to 128KB per 1GB of memory, min 128KB, max MAX_ORDER-1.
 	 */
 	if (!atomic_pool_size)
 		atomic_pool_size = calculate_pool_size(totalram_pages());
-
-	INIT_WORK(&atomic_pool_work, atomic_pool_work_fn);
-
 	atomic_pool_kernel = __dma_atomic_pool_init(atomic_pool_size,
 						    GFP_KERNEL);
-	if (has_managed_dma()) {
-		atomic_pool_dma = __dma_atomic_pool_init(atomic_pool_size,
-						GFP_KERNEL | GFP_DMA);
-	}
-	if (IS_ENABLED(CONFIG_ZONE_DMA32)) {
-		atomic_pool_dma32 = __dma_atomic_pool_init(atomic_pool_size,
-						GFP_KERNEL | GFP_DMA32);
-	}
 
+	INIT_WORK(&atomic_pool_work, atomic_pool_work_fn);
 	dma_atomic_pool_debugfs_init();
 	return 0;
 }
-- 
2.30.2