On Tue, Jun 14, 2016 at 11:01 PM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote: > Hi all- > > If you want to play with virtually mapped stacks, I have it more or > less working on x86 in a branch here: > > https://git.kernel.org/cgit/linux/kernel/git/luto/linux.git/log/?h=x86/vmap_stack > > The core bit (virtually map the stack and fix the accounting) is just > a config option, but it needs the arch to opt-in. I suspect that > every arch will have its own set of silly issues to address to make it > work well. For x86, the silly issues are getting the OOPS to work > right and handling some vmalloc_fault oddities to avoid panicing at > random. Awesome! Some notes/questions: - there are a number of typos in commit messages and comments, just FYI - where is the guard page added? I don't see anything leaving a hole at the end? - where is thread_info? I understand there to be two benefits from vmalloc stack: 1) thread_info can live elsewhere, 2) guard page can exist easily - this seems like it should Oops not warn: WARN_ON_ONCE(vm->nr_pages != THREAD_SIZE / PAGE_SIZE); that being wrong seems like a very bad state to continue from - bikeshed: I think the CONFIG should live in arch/Kconfig (with a description of what an arch needs to support for it) and be called HAVE_ARCH_VMAP_STACK so that archs can select it instead of having multiple definitions of CONFIG_VMAP_STACK in each arch. Thanks for digging into this! -Kees -- Kees Cook Chrome OS & Brillo Security -- 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>