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 X-Spam-Level: X-Spam-Status: No, score=-6.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AE36BC433ED for ; Thu, 20 May 2021 05:13:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 85AF2611AD for ; Thu, 20 May 2021 05:13:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230120AbhETFO7 (ORCPT ); Thu, 20 May 2021 01:14:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43302 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229534AbhETFO6 (ORCPT ); Thu, 20 May 2021 01:14:58 -0400 Received: from mail-pj1-x1033.google.com (mail-pj1-x1033.google.com [IPv6:2607:f8b0:4864:20::1033]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AF5D4C061574 for ; Wed, 19 May 2021 22:13:37 -0700 (PDT) Received: by mail-pj1-x1033.google.com with SMTP id b15-20020a17090a550fb029015dad75163dso4653037pji.0 for ; Wed, 19 May 2021 22:13:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=9cwhp3bw5wRVRJ7C8bZKGP756k5sXb+PQe55pMQ2v5c=; b=j/JX7YiEWDtDQ+bknCG5bF9teVwisdvh9sVh5yX24yiib4iCFhSyvpmXOM1S/Lb3J9 xq+Tk/5f6X4vC3bvXna00fwni6V6KAqezdUDWWkDJnZ0PD6Zp1vs5HGIpPjGA8THKUNF zx8NT88xtKBx6YHocEV6fBdj5eNrYLny4zehM= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=9cwhp3bw5wRVRJ7C8bZKGP756k5sXb+PQe55pMQ2v5c=; b=tl4A5vyNRvE6esy3eOb87JeQrn+J1mUoi5tNXjGyI3e93vVnHyqixwq8HiUzXhqk9J ZYC7lpwPFXsJ0G0hM5iKrSBQagM7spq+71NgbDh229vEg6mt77LNUglw2A04ZTW6K4hw g5ScXXRMjcZNsi01jz2uIUtQ3LcfKi7KGvbqHTVI/UNTZNQ8FiqGpOrF9hoBg+YNaPPH G/dHCNAElf1nECoy8iCp1n5PsR+b1vhRPdIzMwTltEgYn5cVCjZow/gdKTT0KpU6YkAN zeCTRmlbNCG8DjCU5kpy1L/SXjBlCsA5W2JWQlhMkRMU92Zt0QXlJv8AOqozE6+fw9/X d0mg== X-Gm-Message-State: AOAM532hD7GJJFRCyKZS7rDl/7i9xo0QXb/JX/gQAP05u91ht5UcsCOM WqdVYaGxi9MvRiP70CxAvDW2zg== X-Google-Smtp-Source: ABdhPJz3tsVU2Oy+l8umuNLtrOuQcx/bMDNbYaqOGqpLgRq4NZXwY0B2MSxIRiD3wu2Np6NBkQLtcQ== X-Received: by 2002:a17:90b:607:: with SMTP id gb7mr2786738pjb.5.1621487617260; Wed, 19 May 2021 22:13:37 -0700 (PDT) Received: from google.com ([2409:10:2e40:5100:48db:abf:343e:b4f7]) by smtp.gmail.com with ESMTPSA id 23sm868589pgv.90.2021.05.19.22.13.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 May 2021 22:13:36 -0700 (PDT) Date: Thu, 20 May 2021 14:13:32 +0900 From: Sergey Senozhatsky To: Petr Mladek Cc: Sergey Senozhatsky , Andrew Morton , Peter Zijlstra , linux-kernel@vger.kernel.org Subject: Re: [PATCH] watchdog: revert cleanup handling of false positives Message-ID: References: <20210517140612.222750-1-senozhatsky@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (21/05/18 17:36), Petr Mladek wrote: > On Mon 2021-05-17 23:06:12, Sergey Senozhatsky wrote: > > This reverts commit 9bf3bc949f8aeefeacea4b1198db833b722a8e27. > > > > I can reproduce the case when resumed VCPU starts to execute > > is_softlockup() with PVCLOCK_GUEST_STOPPED set on this VCPU: > > > > watchdog_timer_fn() > > { > > ... > > > > kvm_check_and_clear_guest_paused(); > > > > ... > > > > duration = is_softlockup(touch_ts, period_ts); > > if (unlikely(duration)) { > > .... > > } > > } > > > > Which means that guest VCPU has been suspended between > > kvm_check_and_clear_guest_paused() and is_softlockup(), > > and jiffies (clock) thus shifted forward. > > Are jiffies really updated here? I guess so. Why not? VCPUs are not brought up simultaneously, it's up to the host that schedules them. So, for instance, when we resume VCPU-3 and it discovers this_cpu PVCLOCK_GUEST_STOPPED the VCPU-0 can already be resumed, up and running, adding ticks to jiffies. Am I missing the point of your question?