From: David Miller <da...@davemloft.net> Date: Thu, 30 Jan 2014 16:29:26 -0800 (PST)
> From: Richard Yao <r...@gentoo.org> > Date: Thu, 30 Jan 2014 13:02:48 -0500 > >> The 9p-virtio transport does zero copy on things larger than 1024 bytes >> in size. It accomplishes this by returning the physical addresses of >> pages to the virtio-pci device. At present, the translation is usually a >> bit shift. >> >> However, that approach produces an invalid page address when we >> read/write to vmalloc buffers, such as those used for Linux kernle >> modules. This causes QEMU to die printing: >> >> qemu-system-x86_64: virtio: trying to map MMIO memory >> >> This patch enables 9p-virtio to correctly handle this case. This not >> only enables us to load Linux kernel modules off virtfs, but also >> enables ZFS file-based vdevs on virtfs to be used without killing QEMU. >> >> Also, special thanks to both Avi Kivity and Alexander Graf for their >> interpretation of QEMU backtraces. Without their guidence, tracking down >> this bug would have taken much longer. >> >> Signed-off-by: Richard Yao <r...@gentoo.org> >> Acked-by: Alexander Graf <ag...@suse.de> >> Reviewed-by: Will Deacon <will.dea...@arm.com> > > Applied, thanks. Actually I had to revert, is_vmalloc_or_malloc_addr() is not exported to modules, so this change breaks the build. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
