From: Sarah Newman <s...@prgmr.com> Date: Wed, 25 Apr 2018 21:00:34 -0700
> When swiotlb is in use, calling dma_unmap_page means that > the original page mapped with dma_map_page must still be valid > as swiotlb will copy data from its internal cache back to the > originally requested DMA location. When GRO is enabled, > all references to the original frag may be put before > mlx4_en_free_frag is called, meaning the page has been freed > before the call to dma_unmap_page in mlx4_en_free_frag. > > To fix, unmap the page as soon as possible. > > This can be trivially detected by doing the following: > > Compile the kernel with DEBUG_PAGEALLOC > Run the kernel as a Xen Dom0 > Leave GRO enabled on the interface > Run a 10 second or more test with iperf over the interface. > > Signed-off-by: Sarah Newman <s...@prgmr.com> Tariq, I assume I will get this from you in the next set of changes you submit to me. Thanks.
