On Thu, May 01, 2014 at 10:52:47AM +0100, Catalin Marinas wrote: > Does gup_fast walking increment the mm_users? Or is it a requirement of > the calling code? I can't seem to find where this happens. No, its not required at all. One should only walk current->mm with gup_fast, any other usage is broken. And by delaying TLB shootdown, either through disabling IRQs and stalling IPIs or by using RCU freeing, you're guaranteed your own page tables won't disappear underneath your feet. -- 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>