On Thu, Oct 19, 2017 at 06:47:45PM -0400, Jim Quinlan wrote: > The only way to prevent this is to reserve a single page at the end of > the first memory region of any pair that are adjacent in physical > memory. A hack, yes, but I don't see an easier way out of this. Many > if not most of our boards do not have adjacent regions and would not > need this. dma mappings can be much larger than a single page. For the block world take a look at __blk_segment_map_sg which does the merging of contiguous pages into a single SG segment. You'd have to override BIOVEC_PHYS_MERGEABLE to prevent this from happening in your supported architectures for the block layer.
