When a system is under heavy memory pressure, the allocation in
alloc_iova_fast() could still fail even flush_rcache=true, and then
causes dma_ops_alloc_iova() return 0.
pqi_scsi_queue_command
pqi_raid_submit_scsi_cmd_with_io_request
scsi_dma_map
map_sg
dma_ops_alloc_iova
alloc_iova_fast
Later, map_sg()->iommu_map_page() would probably fail due to the invalid
PFN 0, and call free_iova_fast()->iova_rcache_insert() to insert it to
the rcache. Finally, it will trigger the BUG_ON(!iova) here.
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
Fix it by validating the return from the 2nd alloc_iova_fast() in
dma_ops_alloc_iova(), so map_sg() could handle the error condition
immediately.
Signed-off-by: Qian Cai <[email protected]>
---
drivers/iommu/amd_iommu.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 73740b969e62..f24c689b4e01 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -1697,6 +1697,8 @@ static unsigned long dma_ops_alloc_iova(struct device
*dev,
if (!pfn)
pfn = alloc_iova_fast(&dma_dom->iovad, pages,
IOVA_PFN(dma_mask), true);
+ if (!pfn)
+ return DMA_MAPPING_ERROR;
return (pfn << PAGE_SHIFT);
}
--
1.8.3.1
