On 27/08/2019 15:00, Jason Gunthorpe wrote: > On Tue, Aug 27, 2019 at 11:28:20AM +0300, Gal Pressman wrote: >> On 26/08/2019 17:05, Gal Pressman wrote: >>> Hi all, >>> >>> Lately I've been seeing DMA-API call traces on our automated testing runs which >>> complain about overlapping mappings of the same cacheline [1]. >>> The problem is (most likely) caused due to multiple calls to ibv_reg_mr with the >>> same address, which as a result DMA maps the same physical addresses more than 7 >>> (ACTIVE_CACHELINE_MAX_OVERLAP) times. >> >> BTW, on rare occasions I'm seeing the boundary check in check_sg_segment [1] >> fail as well. I don't have a stable repro for it though. >> >> Is this a known issue as well? The comment there states it might be a bug in the >> DMA API implementation, but I'm not sure. >> >> [1] https://elixir.bootlin.com/linux/v5.3-rc3/source/kernel/dma/debug.c#L1230 > > Maybe we are missing a dma_set_seg_boundary ? > > PCI uses low defaults: > > dma_set_max_seg_size(&dev->dev, 65536); > dma_set_seg_boundary(&dev->dev, 0xffffffff); What would you set it to?
