On Fri, Feb 19, 2016 at 09:12:04AM +0100, Rabin Vincent wrote: > Given a device which uses arm_coherent_dma_ops and on which > dev_get_cma_area(dev) returns non-NULL, the following usage of the DMA > API with gfp=0 results in a memory leak and memory corruption. > > p = dma_alloc_coherent(dev, sz, &dma, 0); > if (p) > dma_free_coherent(dev, sz, p, dma); > > The memory leak is because the alloc allocates using > __alloc_simple_buffer() but the free attempts > dma_release_from_contiguous(), which does not do free anything since the > page is not in the CMA area. I'd really like to see a better solution to this problem: over the course of the years, I've seen a number of patches that rearrange the test order at allocation time because of some problem or the other. What we need is a better way to ensure that we use the correct release functionality - having two independent set of tests where the order matters is really not very good. Maybe someone can put some thought into this... -- RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>