From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3C4655F540 for ; Tue, 13 Feb 2024 16:19:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707841143; cv=none; b=YgZZcbihrfIDhlSnGDdYZ0nzZkznbbZLsUlOeGHy0DNDSjBPnSkys8VnxMJiBJ5EOm76RFXNX4tUx55ENDeSRh2vSIlH7YK+RmweZTF0PGYDkDmQHH84jB79fKWOKdEHiHG53ZWixJRmBotg1AmNCQi6nF0rHIG63ucklj549LQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707841143; c=relaxed/simple; bh=zako/G/HB9gTzQ6JN0eka0+jdG1aihgr3k6eoWFjUbo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=BQs1vvgUcVd/z5iz7z3D6AqQ+tMPstitktA0CHw0CdMFg6aUQSJ9NcRz61WxS3DZAAcNb9gFuXycAIoRp5ThHPBFJ+xkNrTnfbksKsqWG6oMVAT5d7yy9S9clnTA8ySBnsHtQZ6wBJCnc44nbyWIwwmomelZQlPP9ECMQiqwCv0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=PtXowNPR; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="PtXowNPR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 59AC1C433F1; Tue, 13 Feb 2024 16:19:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1707841142; bh=zako/G/HB9gTzQ6JN0eka0+jdG1aihgr3k6eoWFjUbo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=PtXowNPRsFn0UGhQnqeWUdI6bVouaYs4W9ihROpvzLOZgFkKQ7+bH2yd83+dBm2O1 KYL1ButHrYe/wwn4XwsQEKbqF80XrABKaSgcUPro3Zd/SW70eSdoL1yh9V0P8C0jcI 2s59px8zrJ0tdKVpNfGdvNG0DOt7x9ggJa9DoMGc= Date: Tue, 13 Feb 2024 17:18:51 +0100 From: Greg KH To: Thomas Gleixner Cc: frederic@kernel.org, paulmck@kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 4.19] hrtimer: Report offline hrtimer enqueue Message-ID: <2024021344-reveal-flying-3752@gregkh> References: <2024021300-sagging-enhance-9113@gregkh> <87h6icgz7o.ffs@tglx> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87h6icgz7o.ffs@tglx> On Tue, Feb 13, 2024 at 04:28:59PM +0100, Thomas Gleixner wrote: > > From: Frederic Weisbecker > > commit dad6a09f3148257ac1773cd90934d721d68ab595 upstream. > > The hrtimers migration on CPU-down hotplug process has been moved > earlier, before the CPU actually goes to die. This leaves a small window > of opportunity to queue an hrtimer in a blind spot, leaving it ignored. > > For example a practical case has been reported with RCU waking up a > SCHED_FIFO task right before the CPUHP_AP_IDLE_DEAD stage, queuing that > way a sched/rt timer to the local offline CPU. > > Make sure such situations never go unnoticed and warn when that happens. > > Fixes: 5c0930ccaad5 ("hrtimers: Push pending hrtimers away from outgoing CPU earlier") > Reported-by: Paul E. McKenney > Signed-off-by: Frederic Weisbecker > Signed-off-by: Paul E. McKenney > Signed-off-by: Thomas Gleixner > Cc: stable@vger.kernel.org > Link: https://lore.kernel.org/r/20240129235646.3171983-4-boqun.feng@gmail.com > --- > > Backport to 4.19 as tglx has too much spare time... Now queued up, thanks. greg k-h