On Mon, May 3, 2021 at 4:27 PM Stefan Metzmacher <metze@xxxxxxxxx> wrote: > > If I remember correctly gdb showed bogus addresses for the backtraces of the io_threads, > as some regs where not cleared. Yeah, so that patch will make the IO thread have the user stack pointer point to the original user stack, but that stack will obviously be used by the original thread which means that it will contain random stuff on it. Doing a childregs->sp = 0; is probably a good idea for that PF_IO_WORKER case, since it really doesn't have - or need - a user stack. Of course, it doesn't really have - or need - any of the other user registers either, but once you fill in the segment stuff to make gdb happy, you might as well fill it all in using the same code that the regular case does. Linus