On 05/09/2016 06:00 AM, Robin Murphy wrote: > On 09/05/16 10:37, Robin Murphy wrote: >> Hi Niklas, >> >> On 08/05/16 11:59, Niklas Söderlund wrote: >>> Hi, >>> >>> While using CONFIG_DMA_API_DEBUG i came across this warning which I >>> think is a false positive. As shown dma_sync_single_for_device() are >>> called from the dma_map_single() call path. This triggers the warning >>> since the dma-debug code have not yet been made aware of the mapping. >> >> Almost right ;) The thing being mapped (the SPI device's buffer) and the >> thing being synced (the IOMMU's PTE) are entirely unrelated. Due to the >> current of_iommu_init() setup, the IOMMU is probed long before >> dma_debug_init() gets called, therefore DMA debug is missing entries for >> some of the initial page table mappings and gets confused when we update >> them later. What was the eventual followup/fix for this? We're seeing similar traces to this during internal testing of 4.11 kernels. Jon. -- Computer Architect
