set_memory_decrypted() may block so it is not possible to do non-blocking allocations through the DMA API for devices that required unencrypted memory.
The solution is to expand the atomic DMA pools for the various possible gfp requirements as a means to prevent an unnecessary depletion of lowmem. These atomic DMA pools are kept unencrypted so they can immediately be used for non-blocking allocations. Since the need for this type of memory depends on the kernel config and devices being used, these pools are also dynamically expandable. Some of these patches could be squashed into each other, but they were separated out to ease code review. This patchset is based on 5.6-rc4. --- arch/x86/Kconfig | 1 + drivers/iommu/dma-iommu.c | 5 +- include/linux/dma-direct.h | 2 + include/linux/dma-mapping.h | 6 +- kernel/dma/direct.c | 17 ++-- kernel/dma/remap.c | 173 +++++++++++++++++++++++++----------- 6 files changed, 140 insertions(+), 64 deletions(-) _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
