From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-f199.google.com (mail-pf1-f199.google.com [209.85.210.199]) by kanga.kvack.org (Postfix) with ESMTP id 5EC0C8E0001 for ; Wed, 26 Sep 2018 18:36:19 -0400 (EDT) Received: by mail-pf1-f199.google.com with SMTP id v9-v6so619302pff.4 for ; Wed, 26 Sep 2018 15:36:19 -0700 (PDT) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id l15-v6si216878pgh.593.2018.09.26.15.36.17 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 26 Sep 2018 15:36:18 -0700 (PDT) Date: Wed, 26 Sep 2018 15:36:15 -0700 From: Andrew Morton Subject: Re: [PATCH v5 2/4] mm: Provide kernel parameter to allow disabling page init poisoning Message-Id: <20180926153615.90661e27d0713a02651b2282@linux-foundation.org> In-Reply-To: References: <20180925200551.3576.18755.stgit@localhost.localdomain> <20180925201921.3576.84239.stgit@localhost.localdomain> <20180926073831.GC6278@dhcp22.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: Michal Hocko , Alexander Duyck , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, pavel.tatashin@microsoft.com, dave.jiang@intel.com, jglisse@redhat.com, rppt@linux.vnet.ibm.com, dan.j.williams@intel.com, logang@deltatee.com, mingo@kernel.org, kirill.shutemov@linux.intel.com On Wed, 26 Sep 2018 08:36:47 -0700 Dave Hansen wrote: > On 09/26/2018 12:38 AM, Michal Hocko wrote: > > Why cannot you simply go with [no]vm_page_poison[=on/off]? > > I was trying to look to the future a bit, if we end up with five or six > more other options we want to allow folks to enable/disable. I don't > want to end up in a situation where we have a bunch of different knobs > to turn all this stuff off at runtime. > > I'd really like to have one stop shopping so that folks who have a > system that's behaving well and don't need any debugging can get some of > their performance back. > > But, the *primary* thing we want here is a nice, quick way to turn as > much debugging off as we can. A nice-to-have is a future-proof, > slub-style option that will centralize things. Yup. DEBUG_VM just covers too much stuff nowadays. A general way to make these thing more fine-grained and without requiring a rebuild would be great. And I expect that quite a few of the debug features could be enabled/disabled after bootup as well, so a /proc knob is probably in our future. Any infrastructure which is added to support a new kernel-command-line option should be designed with that in mind.