On Thu, 18 Sep 2025 19:32:20 +0200 Peter Zijlstra <[email protected]> wrote:
> > Now, task_work_run() is in the exit_to_user_mode_loop() which is notably > > *before* exit_to_user_mode() which does the unwind_reset_info(). > > > > What happens if we get an NMI requesting an unwind after > > unwind_reset_info() while still very much being in the kernel on the way > > out? > > AFAICT it will try and do a task_work_add(TWA_RESUME) from NMI context, > and this will fail horribly. > > If you do something like: > > twa_mode = in_nmi() ? TWA_NMI_CURRENT : TWA_RESUME; > task_work_add(foo, twa_mode); > > it might actually work. Ah, the comment for TWA_RESUME didn't express this restriction. That does look like that would work as the way I expected task_work to handle this case. -- Steve
