Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Tue, 18 May 2021 08:55:17 +0900
From:   Sergey Senozhatsky <senozhatsky@chromium.org>
To:     Petr Mladek <pmladek@suse.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        Ingo Molnar <mingo@kernel.org>,
        Laurence Oberman <loberman@redhat.com>,
        Michal Hocko <mhocko@suse.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Vincent Whitchurch <vincent.whitchurch@axis.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sergey Senozhatsky <senozhatsky@chromium.org>,
        Sasha Levin <sashal@kernel.org>
Subject: Re: [PATCH 5.12 123/363] watchdog: cleanup handling of false
 positives
Message-ID: <YKMCZWhhNS9kIOoR@google.com>
References: <20210517140302.508966430@linuxfoundation.org>
 <20210517140306.783130885@linuxfoundation.org>
 <YKJ+INpik2i9IhZN@alley>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <YKJ+INpik2i9IhZN@alley>
Precedence: bulk

On (21/05/17 16:30), Petr Mladek wrote:
> On Mon 2021-05-17 15:59:49, Greg Kroah-Hartman wrote:
> > From: Petr Mladek <pmladek@suse.com>
> > 
> > [ Upstream commit 9bf3bc949f8aeefeacea4b1198db833b722a8e27 ]
> > 
> > Commit d6ad3e286d2c ("softlockup: Add sched_clock_tick() to avoid kernel
> > warning on kgdb resume") introduced touch_softlockup_watchdog_sync().
> 
> [...]
> 
> > Make the code more straightforward:
> > 
> > 1. Always call kvm_check_and_clear_guest_paused() at the very
> >    beginning to handle PVCLOCK_GUEST_STOPPED. It touches the watchdog
> >    when the quest did sleep.
> > 
> > 2. Handle the situation when the watchdog has been touched
> >    (SOFTLOCKUP_DELAY_REPORT is set).
> > 
> >    Call sched_clock_tick() when touch_*sync() variant was used. It makes
> >    sure that the timestamp will be up to date even when it has been
> >    touched in atomic context or quest did sleep.
> > 
> > As a result, kvm_check_and_clear_guest_paused() is called on a single
> > location.  And the right timestamp is always set when returning from the
> > timer callback.
> > 
> > Link: https://lkml.kernel.org/r/20210311122130.6788-7-pmladek@suse.com
> 
> Please, remove this patch from the stable backport. It might
> cause false softlockup reports, see

Oh, I didn't know about the stable backport. Thank you for taking care of it.