Hi Manfred, On 12/29, Manfred Spraul wrote: > > Hi Oleg, > > On 12/29/24 2:13 PM, Oleg Nesterov wrote: > >Sorry for the noise... > > > >and currently this is fine. Heh, please see below. > But if we want to add the wq_has_sleeper() > >checks into fs/pipe.c then pipe_poll() needs smp_mb() after it calls > >poll_wait(). > > > >Agreed? > > Yes, agreed. > > Just the comment in pipe_poll() was a bit tricky for me. Well yes, but... It turns out I didn't grep enough. See fs/splice.c and wakeup_pipe_readers/writers (which should use wq_has_sleeper() for grep sake). And I don't understand why do these helpers use key == NULL... So it seems that pipe_poll() already needs smp_mb() to fix the current code, at least in theory. I'll recheck and send the patch(es). Oleg.
