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 5008EC433FE for ; Sat, 15 Oct 2022 15:35:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229651AbiJOPfn (ORCPT ); Sat, 15 Oct 2022 11:35:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50358 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229866AbiJOPf1 (ORCPT ); Sat, 15 Oct 2022 11:35:27 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0D10230F69; Sat, 15 Oct 2022 08:35:16 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 92F6560E2D; Sat, 15 Oct 2022 15:35:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 93849C433C1; Sat, 15 Oct 2022 15:35:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1665848115; bh=kodHl9TTu9t56McWQSFGYH03s9jx5pwxhnqq0rGzmJM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=uXZXoCFh+PkM/zBnSieAFrMQ8LyjSlIZdou6GVRMfw4sbUKLcHW3dbGpvn7WXIqC2 A0udzRmOIlyimhz5j1nYsjdPEG/OAtT8Dkg4LllURrh3hLBVKMtGMZBJclz7IEyqgc 1f4fKBuONHzkBLTit0d8KJ8G78NvtQVeq8+rfpSA= Date: Sat, 15 Oct 2022 17:36:00 +0200 From: "gregkh@linuxfoundation.org" To: "Bhatnagar, Rishabh" Cc: "Herrenschmidt, Benjamin" , "sashal@kernel.org" , "tglx@linutronix.de" , "stable@vger.kernel.org" , "mingo@redhat.com" , "linux-kernel@vger.kernel.org" , "Bacco, Mike" Subject: Re: [PATCH 0/6] IRQ handling patches backport to 4.14 stable Message-ID: References: <20220929210651.12308-1-risbhat@amazon.com> <58294d242fc256a48abb31926232565830197f02.camel@amazon.com> <0d923959-1b93-6133-6609-ac2c0c5711ee@amazon.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <0d923959-1b93-6133-6609-ac2c0c5711ee@amazon.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 14, 2022 at 12:00:31PM -0700, Bhatnagar, Rishabh wrote: > > On 10/9/22 10:50 AM, Bhatnagar, Rishabh wrote: > > > > On 10/6/22 8:07 PM, Herrenschmidt, Benjamin wrote: > > > (putting my @amazon.com hat on) > > > > > > On Sun, 2022-10-02 at 17:30 +0200, Greg KH wrote: > > > > > > > > > > On Thu, Sep 29, 2022 at 09:06:45PM +0000, Rishabh Bhatnagar wrote: > > > > > This patch series backports a bunch of patches related IRQ handling > > > > > with respect to freeing the irq line while IRQ is in flight at CPU > > > > > or at the hardware level. > > > > > Recently we saw this issue in serial 8250 driver where the IRQ was > > > > > being > > > > > freed while the irq was in flight or not yet delivered to the CPU. > > > > > As a > > > > > result the irqchip was going into a wedged state and IRQ was not > > > > > getting > > > > > delivered to the cpu. These patches helped fixed the issue in 4.14 > > > > > kernel. > > > > Why is the serial driver freeing an irq while the system is running? > > > > Ah, this could happen on a tty hangup, right? > > > Right. Rishabh answered that separately. > > > > > > > > Let us know if more patches need backporting. > > > > What hardware platform were these patches tested on to verify they > > > > work properly?  And why can't they move to 4.19 or newer if they > > > > really need this fix?  What's preventing that? > > > > > > > > As Amazon doesn't seem to be testing 4.14.y -rc releases, I find it > > > > odd that you all did this backport.  Is this a kernel that you all > > > > care about? > > > These were tested on a collection of EC2 instances, virtual and metal I > > > believe (Rishabh, please confirm). > > Yes these patches were tested on multiple virt/metal EC2 instances. > > > > > > Amazon Linux 2 runs 4.14 or 5.10. Unfortunately we still have to > > > support customers running the former. > > > > > > We'll be including these patches in our releases, we thought it would > > > be nice to have them in -stable as well for the sake of whoever else > > > might be still using this kernel. No huge deal if they don't. > > > > > > As for testing -rc's, yes, we need to get better at that (and publish > > > what we test). Point taken :-) > > > > > > Cheers, > > > Ben. > > > > Hi Greg > > Let us know if you think it would be beneficial to take these backports for > 4.14 stable. Give me some time after -rc1 is out to review this then as we are swamped right now. > We can drop this patch set otherwise. You can do whatever you want with your tree :) thanks, greg k-h