From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-f198.google.com (mail-pf1-f198.google.com [209.85.210.198]) by kanga.kvack.org (Postfix) with ESMTP id 4941D8E0001 for ; Wed, 26 Sep 2018 03:38:38 -0400 (EDT) Received: by mail-pf1-f198.google.com with SMTP id b17-v6so4337557pfo.20 for ; Wed, 26 Sep 2018 00:38:38 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id h6-v6si4838675pls.150.2018.09.26.00.38.36 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 26 Sep 2018 00:38:37 -0700 (PDT) Date: Wed, 26 Sep 2018 09:38:31 +0200 From: Michal Hocko Subject: Re: [PATCH v5 2/4] mm: Provide kernel parameter to allow disabling page init poisoning Message-ID: <20180926073831.GC6278@dhcp22.suse.cz> References: <20180925200551.3576.18755.stgit@localhost.localdomain> <20180925201921.3576.84239.stgit@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180925201921.3576.84239.stgit@localhost.localdomain> Sender: owner-linux-mm@kvack.org List-ID: To: Alexander Duyck Cc: linux-mm@kvack.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, pavel.tatashin@microsoft.com, dave.jiang@intel.com, dave.hansen@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 Tue 25-09-18 13:20:12, Alexander Duyck wrote: [...] > + vm_debug[=options] [KNL] Available with CONFIG_DEBUG_VM=y. > + May slow down system boot speed, especially when > + enabled on systems with a large amount of memory. > + All options are enabled by default, and this > + interface is meant to allow for selectively > + enabling or disabling specific virtual memory > + debugging features. > + > + Available options are: > + P Enable page structure init time poisoning > + - Disable all of the above options I agree with Dave that this is confusing as hell. So what does vm_debug (without any options means). I assume it's NOP and all debugging is enabled and that is the default. What if I want to disable _only_ the page struct poisoning. The weird lookcing `-' will disable all other options that we might gather in the future. Why cannot you simply go with [no]vm_page_poison[=on/off]? -- Michal Hocko SUSE Labs