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Mon, 16 Apr 2018 13:23:32 -0400 From: Sasha Levin To: Pavel Machek CC: Steven Rostedt , Linus Torvalds , Petr Mladek , "stable@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "akpm@linux-foundation.org" , "linux-mm@kvack.org" , Cong Wang , Dave Hansen , Johannes Weiner , Mel Gorman , Michal Hocko , Vlastimil Babka , Peter Zijlstra , Jan Kara , Mathieu Desnoyers , Tetsuo Handa , Byungchul Park , Tejun Heo Subject: Re: [PATCH AUTOSEL for 4.14 015/161] printk: Add console owner and waiter logic to load balance console writes Thread-Topic: [PATCH AUTOSEL for 4.14 015/161] printk: Add console owner and waiter logic to load balance console writes Thread-Index: AQHTz5h7IvK2v80d0k6VVqDoPwJEM6P4GK8AgAnYKwCAAX5DAIAAHfKAgAAFIICAAAchAIAAAugAgAAB5YCAAAMcgIAAAh8AgAAH3gCAAATcgA== Date: Mon, 16 Apr 2018 17:23:30 +0000 Message-ID: <20180416172327.GK2341@sasha-vm> References: <20180415144248.GP2341@sasha-vm> <20180416093058.6edca0bb@gandalf.local.home> <20180416113629.2474ae74@gandalf.local.home> <20180416160200.GY2341@sasha-vm> <20180416121224.2138b806@gandalf.local.home> <20180416161911.GA2341@sasha-vm> <20180416123019.4d235374@gandalf.local.home> <20180416163754.GD2341@sasha-vm> <20180416170604.GC11034@amd> In-Reply-To: <20180416170604.GC11034@amd> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [52.168.54.252] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;DM5PR2101MB1096;7:7WvkA4w3/0O6uEABlPzwRVgyfTM8SkeiQezwBUh218iZJOEJWmBYEYEto2ete2mAjxR6T6iLSptK5fnyibr1PcgTEve+GAXdXBzYzb5uCws7kfom65AhrIIgZyNaS65Sc5Ycn6LX7IgftHuKveNlTck1CnrQHoyFL0rGG8VC/08/Svqe/5dPUyv+Nbvm3jI7Vw4VRCqS2sQu2Pa+1KTboWV6F6IttZPX/rqwVsp/DQAjL3PjaaO62h9z6zFyU0Tu;20:sDI47CPwK77yduvujd+Jh0DO0ha8e5MQyjw0W0xrOh20LX0aGhxUwSNrNvipurmkbX7+k98fv3+uA5AhCLvX+17EcPwFCkulZSV5rNDiLcUJiReMCt49Ak3NnHBcfTlq2zK3tSlfD1xQBz5ohgkFvPX6mlWBL0YHctBaSPW+ZAc= x-ms-exchange-antispam-srfa-diagnostics: SOS; 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x-microsoft-antispam-message-info: ynbqpEOEYxj0xSgNCCgkJygbe6HWK4nHKY4/y2K2aVTNTst1fjXp3Rfvlca/N2ahCEncaoq7VOLBV/cffRei6h1B5S6eUllx4Fq6qdgOMdfMLV0dGV5/Q3xCgNiQ/m5i4rssSmAxseIYSlAbTAgzw+qx1dqKqdW05v2eReXdrNnvRQGnMkkUCh0dIv3LZnPm spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="us-ascii" Content-ID: <3D765F417F57E84DB8B91271B39281FA@namprd21.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Office365-Filtering-Correlation-Id: 2d77e671-9330-4378-615b-08d5a3bec62b X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-Network-Message-Id: 2d77e671-9330-4378-615b-08d5a3bec62b X-MS-Exchange-CrossTenant-originalarrivaltime: 16 Apr 2018 17:23:30.4757 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR2101MB1096 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Mon, Apr 16, 2018 at 07:06:04PM +0200, Pavel Machek wrote: >On Mon 2018-04-16 16:37:56, Sasha Levin wrote: >> On Mon, Apr 16, 2018 at 12:30:19PM -0400, Steven Rostedt wrote: >> >On Mon, 16 Apr 2018 16:19:14 +0000 >> >Sasha Levin wrote: >> > >> >> >Wait! What does that mean? What's the purpose of stable if it is as >> >> >broken as mainline? >> >> >> >> This just means that if there is a fix that went in mainline, and the >> >> fix is broken somehow, we'd rather take the broken fix than not. >> >> >> >> In this scenario, *something* will be broken, it's just a matter of >> >> what. We'd rather have the same thing broken between mainline and >> >> stable. >> > >> >Honestly, I think that removes all value of the stable series. I >> >remember when the stable series were first created. People were saying >> >that it wouldn't even get to more than 5 versions, because the bar for >> >backporting was suppose to be very high. Today it's just a fork of the >> >kernel at a given version. No more features, but we will be OK with >> >regressions. I'm struggling to see what the benefit of it is suppose to >> >be? >> >> It's not "OK with regressions". >> >> Let's look at a hypothetical example: You have a 4.15.1 kernel that has >> a broken printf() behaviour so that when you: >> >> pr_err("%d", 5) >> >> Would print: >> >> "Microsoft Rulez" >> >> Bad, right? So you went ahead and fixed it, and now it prints "5" as you >> might expect. But alas, with your patch, running: >> >> pr_err("%s", "hi!") >> >> Would show a cat picture for 5 seconds. >> >> Should we take your patch in -stable or not? If we don't, we're stuck >> with the original issue while the mainline kernel will behave >> differently, but if we do - we introduce a new regression. > >Of course not. > >- It must be obviously correct and tested. > >If it introduces new bug, it is not correct, and certainly not >obviously correct. As you might have noticed, we don't strictly follow the rules. Take a look at the whole PTI story as an example. It's way more than 100 lines, it's not obviously corrent, it fixed more than 1 thing, and so on, and yet it went in -stable! Would you argue we shouldn't have backported PTI to -stable?=