On Wed, 20 Feb 2019 14:57:31 +0100 Jann Horn <jannh@xxxxxxxxxx> wrote: > > (*) BTW, there is another concern to use _from_user APIs in kprobe. Are those > > APIs might sleep?? > > If you want to access userspace without sleeping, and ignore data in > non-present pages, you can do `pagefault_disable(); err = > __copy_from_user_inatomic(...); pagefault_enable();`. (Actually, maybe > the kernel should have a helper for that...) I was about to say pretty much the same thing (about using _inatomic()), but yeah, we should also have a helper function if we don't already to include the page_fault_disable/enable() too. -- Steve
