On Mon, Aug 24, 2015 at 05:15:22PM +0300, Andrey Ryabinin wrote: > Yes, ~130Mb (3G/1G split) should work. 512Mb shadow is optional. > The only advantage of 512Mb shadow is better handling of user memory > accesses bugs > (access to user memory without copy_from_user/copy_to_user/strlen_user etc API). No need for that to be handed by KASan. I have patches in linux-next, now acked by Will, which prevent the kernel accessing userspace with zero memory footprint. No need for remapping, we have a way to quickly turn off access to userspace mapped pages on non-LPAE 32-bit CPUs. (LPAE is not supported yet - Catalin will be working on that using the hooks I'm providing once he returns.) This isn't a debugging thing, it's a security hardening thing. Some use-after-free bugs are potentially exploitable from userspace. See the recent blackhat conference paper. -- FTTC broadband for 0.8mile line: currently at 10.5Mbps 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>