swiotlb: check alloc_size before the allocation of a new memory pool

The allocation request for swiotlb contiguous memory greater than
128*2KB cannot be fulfilled because it exceeds the maximum contiguous
memory limit. If the swiotlb memory we allocate is larger than 128*2KB,
swiotlb_find_slots() will still schedule the allocation of a new memory
pool, which will increase memory overhead.

Fix it by adding a check with alloc_size no more than 128*2KB before
scheduling the allocation of a new memory pool in swiotlb_find_slots().

Signed-off-by: ZhangPeng <zhangpeng362@huawei.com>
Reviewed-by: Petr Tesarik <petr.tesarik1@huawei-partners.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index e20b856255ef66529fff5afaf5bea52e41b8ab47..96f832d828fd4691f178575558ec40d9094baf82 100644 (file)
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -1136,6 +1136,9 @@ static int swiotlb_find_slots(struct device *dev, phys_addr_t orig_addr,
        int cpu, i;
        int index;
 
+       if (alloc_size > IO_TLB_SEGSIZE * IO_TLB_SIZE)
+               return -1;
+
        cpu = raw_smp_processor_id();
        for (i = 0; i < default_nareas; ++i) {
                index = swiotlb_search_area(dev, cpu, i, orig_addr, alloc_size,