From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C74B6C433EF for ; Mon, 4 Apr 2022 08:32:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239194AbiDDIer (ORCPT ); Mon, 4 Apr 2022 04:34:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51424 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232144AbiDDIep (ORCPT ); Mon, 4 Apr 2022 04:34:45 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 45A7A35268 for ; Mon, 4 Apr 2022 01:32:49 -0700 (PDT) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1649061167; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=QD9Nb7yJabZzo/4wQdWDUvSpWf7rTbKauGlMZ2wI9I4=; b=BDdixwPuv6Sc1CB0q0w75VqdaMnSHVZhfcGr1zxwC+BJn+oDayYQ9hIPWw3z8vUz+8IGWS h4rBqMyo15a9gaabE7WiT8CpfO3n/5dYuNAMwlNp8hn1IAqBuHTiFcjvfUVVUVLAN+o0oS LJLgLyhCrwN45JSBN2b0Mrn+Bwpta6sxcq/BXA+Nb1G61WYDoIRgAbel1QNk1ssVKCW6Mw xjzgDQv+Fnc1XWd4XnNSl7L8YXIBuHM8oLPyhZ+OjDBFx4LSdBdtyg5oTP17v4zWz0lNMZ rPuBRS9eYXpZo126u4zR6dxFWX1C5IYjkxgX0WHkOflbuC60kQgqbgvvozc+0w== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1649061167; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=QD9Nb7yJabZzo/4wQdWDUvSpWf7rTbKauGlMZ2wI9I4=; b=lRWZ7MgFKxPyOkDySzlC40J/O5OtqKbz8MwSLvMjPf+lUNANwIHw+OpklTwEvotsJ4cX0q 1M6eI6d32cKXu7Bg== To: Johannes Berg , Vincent Whitchurch Cc: linux-um@lists.infradead.org, linux-kernel@vger.kernel.org, Anna-Maria Gleixner , Frederic Weisbecker Subject: Re: UML time-travel warning from __run_timers In-Reply-To: References: <20220330110156.GA9250@axis.com> <84f9d627092660c38400b607198c3b83f795be7f.camel@sipsolutions.net> <877d86m978.ffs@tglx> <32423b7c0e3a490093ceaca750e8669ac67902c6.camel@sipsolutions.net> <87pmlykksj.ffs@tglx> Date: Mon, 04 Apr 2022 10:32:46 +0200 Message-ID: <87ee2dl041.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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); base->clk++; base->next_expiry = __next_timer_interrupt(base);