From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from s3.sipsolutions.net ([2a01:4f8:191:4433::2] helo=sipsolutions.net) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nbIDQ-00DsUv-Lj for linux-um@lists.infradead.org; Mon, 04 Apr 2022 08:37:40 +0000 Message-ID: <85f7ce7bc7ddcf1f67b52375b7fabaca8d254e5a.camel@sipsolutions.net> Subject: Re: UML time-travel warning from __run_timers From: Johannes Berg Date: Mon, 04 Apr 2022 10:37:30 +0200 In-Reply-To: <87ee2dl041.ffs@tglx> References: <20220330110156.GA9250@axis.com> <84f9d627092660c38400b607198c3b83f795be7f.camel@sipsolutions.net> <877d86m978.ffs@tglx> <32423b7c0e3a490093ceaca750e8669ac67902c6.camel@sipsolutions.net> <87pmlykksj.ffs@tglx> <87ee2dl041.ffs@tglx> MIME-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-um" Errors-To: linux-um-bounces+geert=linux-m68k.org@lists.infradead.org To: Thomas Gleixner , Vincent Whitchurch Cc: linux-um@lists.infradead.org, linux-kernel@vger.kernel.org, Anna-Maria Gleixner , Frederic Weisbecker On Mon, 2022-04-04 at 10:32 +0200, Thomas Gleixner wrote: > On Mon, Apr 04 2022 at 09:02, Johannes Berg wrote: > > On Sun, 2022-04-03 at 21:51 +0200, Thomas Gleixner wrote: > > > but that's fine and it is overwritten by every timer which is inserted > > > to expire before that. So that's not an issue as the prandom timer is > > > firing and rearmed. > > > > No, as I said before, there's never any timer with base 1 (BASE_DEF) in > > the config we have. The prandom timer is not TIMER_DEFERRABLE (it > > probably could be, but it's not now). There's no deferrable timer at > > all. Once there is at least one, the warning goes away. > > Groan. I overlooked the deferrable part. Yes, you are right. next_expiry > of the deferrable base is stale when there is no timer queued up to the > point where base->clk reaches the initial next_expiry value. So the > check is bogus. > > Thanks, > > tglx > --- > --- a/kernel/time/timer.c > +++ b/kernel/time/timer.c > @@ -1724,9 +1724,8 @@ static inline void __run_timers(struct t > /* > * The only possible reason for not finding any expired > * timer at this clk is that all matching timers have been > - * dequeued. > + * dequeued or no timer has been ever queued. > */ > - WARN_ON_ONCE(!levels && !base->next_expiry_recalc); > So I'm pretty sure we don't even need to test a patch simply removing the WARN_ON_ONCE() since the entire problem Vincent reported was hitting the WARN_ON_ONCE :) (And I'm pretty sure I did at some point test some additional condition inside it) Are you going to merge that patch? johannes _______________________________________________ linux-um mailing list linux-um@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-um