Messages in this thread | | | Subject | Re: [PATCH 0/2] Fix incorrect warning from dma-debug | From | Jon Masters <> | Date | Sat, 6 May 2017 20:06:46 -0400 |
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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
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