From 8cf66504210d308a35cca35fe9c310b1241f9fa7 Mon Sep 17 00:00:00 2001 From: Qian Cai Date: Thu, 11 Jul 2019 12:17:45 -0400 Subject: [PATCH] iommu/amd: fix a crash in iova_magazine_free_pfns The commit b3aa14f02254 ("iommu: remove the mapping_error dma_map_ops method") incorrectly changed the checking from dma_ops_alloc_iova() in map_sg() causes a crash under memory pressure as dma_ops_alloc_iova() never return DMA_MAPPING_ERROR on failure but 0, so the error handling is all wrong. kernel BUG at drivers/iommu/iova.c:801! Workqueue: kblockd blk_mq_run_work_fn RIP: 0010:iova_magazine_free_pfns+0x7d/0xc0 Call Trace: free_cpu_cached_iovas+0xbd/0x150 alloc_iova_fast+0x8c/0xba dma_ops_alloc_iova.isra.6+0x65/0xa0 map_sg+0x8c/0x2a0 scsi_dma_map+0xc6/0x160 pqi_aio_submit_io+0x1f6/0x440 [smartpqi] pqi_scsi_queue_command+0x90c/0xdd0 [smartpqi] scsi_queue_rq+0x79c/0x1200 blk_mq_dispatch_rq_list+0x4dc/0xb70 blk_mq_sched_dispatch_requests+0x249/0x310 __blk_mq_run_hw_queue+0x128/0x200 blk_mq_run_work_fn+0x27/0x30 process_one_work+0x522/0xa10 worker_thread+0x63/0x5b0 kthread+0x1d2/0x1f0 ret_from_fork+0x22/0x40 Fixes: b3aa14f02254 ("iommu: remove the mapping_error dma_map_ops method") Signed-off-by: Qian Cai Reviewed-by: Christoph Hellwig Signed-off-by: Linus Torvalds --- drivers/iommu/amd_iommu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c index 73740b9..b607a92 100644 --- a/drivers/iommu/amd_iommu.c +++ b/drivers/iommu/amd_iommu.c @@ -2533,7 +2533,7 @@ static int map_sg(struct device *dev, struct scatterlist *sglist, npages = sg_num_pages(dev, sglist, nelems); address = dma_ops_alloc_iova(dev, dma_dom, npages, dma_mask); - if (address == DMA_MAPPING_ERROR) + if (!address) goto out_err; prot = dir2prot(direction); -- 2.7.4