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 B9998C433FE for ; Fri, 14 Oct 2022 19:00:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229865AbiJNTAt (ORCPT ); Fri, 14 Oct 2022 15:00:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57980 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229919AbiJNTAs (ORCPT ); Fri, 14 Oct 2022 15:00:48 -0400 Received: from smtp-fw-80007.amazon.com (smtp-fw-80007.amazon.com [99.78.197.218]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 47FA325C78; Fri, 14 Oct 2022 12:00:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1665774046; x=1697310046; h=message-id:date:mime-version:subject:from:to:cc: references:in-reply-to:content-transfer-encoding; bh=GXoD9gRB2Hvbmyc4m6TRPnO3SU6oxhVMCZ99nFZXCTs=; b=kmlbJDgDARB2uYSv8s75cK/H/EycW2ZXIKh8BNOgP97RMZUKKYQ3EJlA Ae7gF4kERrThUVSyTdGSIRqKYIxf7GDkTYaYwjW120gqrXnH93iQqa82V w/NymC6n+ptkN5kEcpXWb6tpja+9JK+yowF8L0+cM5HVI3NtDTcpNU7vu Y=; X-IronPort-AV: E=Sophos;i="5.95,185,1661817600"; d="scan'208";a="140426874" Received: from pdx4-co-svc-p1-lb2-vlan3.amazon.com (HELO email-inbound-relay-iad-1d-b48bc93b.us-east-1.amazon.com) ([10.25.36.214]) by smtp-border-fw-80007.pdx80.corp.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Oct 2022 19:00:45 +0000 Received: from EX13MTAUWC002.ant.amazon.com (iad12-ws-svc-p26-lb9-vlan3.iad.amazon.com [10.40.163.38]) by email-inbound-relay-iad-1d-b48bc93b.us-east-1.amazon.com (Postfix) with ESMTPS id 6B880C090F; Fri, 14 Oct 2022 19:00:43 +0000 (UTC) Received: from EX19D002UWC004.ant.amazon.com (10.13.138.186) by EX13MTAUWC002.ant.amazon.com (10.43.162.240) with Microsoft SMTP Server (TLS) id 15.0.1497.42; Fri, 14 Oct 2022 19:00:42 +0000 Received: from [192.168.28.131] (10.43.162.230) by EX19D002UWC004.ant.amazon.com (10.13.138.186) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1118.15; Fri, 14 Oct 2022 19:00:42 +0000 Message-ID: <0d923959-1b93-6133-6609-ac2c0c5711ee@amazon.com> Date: Fri, 14 Oct 2022 12:00:31 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.3.2 Subject: Re: [PATCH 0/6] IRQ handling patches backport to 4.14 stable Content-Language: en-US From: "Bhatnagar, Rishabh" To: "Herrenschmidt, Benjamin" , "gregkh@linuxfoundation.org" CC: "sashal@kernel.org" , "tglx@linutronix.de" , "stable@vger.kernel.org" , "mingo@redhat.com" , "linux-kernel@vger.kernel.org" , "Bacco, Mike" References: <20220929210651.12308-1-risbhat@amazon.com> <58294d242fc256a48abb31926232565830197f02.camel@amazon.com> In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.43.162.230] X-ClientProxiedBy: EX13D08UWC001.ant.amazon.com (10.43.162.110) To EX19D002UWC004.ant.amazon.com (10.13.138.186) Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 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. We can drop this patch set otherwise. Thanks alot, Rishabh