dma-pool: fix too large DMA pools on medium memory size systems

On systems with at least 32 MiB, but less than 32 GiB of RAM, the DMA
memory pools are much larger than intended (e.g. 2 MiB instead of 128
KiB on a 256 MiB system).

Fix this by correcting the calculation of the number of GiBs of RAM in
the system.  Invert the order of the min/max operations, to keep on
calculating in pages until the last step, which aids readability.

Fixes: 1d659236fb43c4d2 ("dma-pool: scale the default DMA coherent pool size with memory capacity")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c
index 35bb51c31fff370f324a0d705434b32775b2a590..8cfa01243ed27b6fa3d7ce5718fc69b2d6a55cf1 100644 (file)
--- a/kernel/dma/pool.c
+++ b/kernel/dma/pool.c
@@ -175,10 +175,9 @@ static int __init dma_atomic_pool_init(void)
         * sizes to 128KB per 1GB of memory, min 128KB, max MAX_ORDER-1.
         */
        if (!atomic_pool_size) {
-               atomic_pool_size = max(totalram_pages() >> PAGE_SHIFT, 1UL) *
-                                       SZ_128K;
-               atomic_pool_size = min_t(size_t, atomic_pool_size,
-                                        1 << (PAGE_SHIFT + MAX_ORDER-1));
+               unsigned long pages = totalram_pages() / (SZ_1G / SZ_128K);
+               pages = min_t(unsigned long, pages, MAX_ORDER_NR_PAGES);
+               atomic_pool_size = max_t(size_t, pages << PAGE_SHIFT, SZ_128K);
        }
        INIT_WORK(&atomic_pool_work, atomic_pool_work_fn);