From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id A542821959CB2 for ; Wed, 12 Sep 2018 08:25:19 -0700 (PDT) Subject: Re: [PATCH 1/4] mm: Provide kernel parameter to allow disabling page init poisoning References: <20180910232615.4068.29155.stgit@localhost.localdomain> <20180910234341.4068.26882.stgit@localhost.localdomain> <20180912141053.GL10951@dhcp22.suse.cz> From: Dave Hansen Message-ID: <841e8101-40db-9ff2-f688-5f175d91fc31@intel.com> Date: Wed, 12 Sep 2018 08:23:58 -0700 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Alexander Duyck , mhocko@kernel.org Cc: pavel.tatashin@microsoft.com, linux-nvdimm@lists.01.org, LKML , linux-mm , jglisse@redhat.com, Andrew Morton , Ingo Molnar , "Kirill A. Shutemov" List-ID: On 09/12/2018 07:49 AM, Alexander Duyck wrote: >>> + page_init_poison= [KNL] Boot-time parameter changing the >>> + state of poisoning of page structures during early >>> + boot. Used to verify page metadata is not accessed >>> + prior to initialization. Available with >>> + CONFIG_DEBUG_VM=y. >>> + off: turn off poisoning >>> + on: turn on poisoning (default) >>> + >> what about the following wording or something along those lines >> >> Boot-time parameter to control struct page poisoning which is a >> debugging feature to catch unitialized struct page access. This option >> is available only for CONFIG_DEBUG_VM=y and it affects boot time >> (especially on large systems). If there are no poisoning bugs reported >> on the particular system and workload it should be safe to disable it to >> speed up the boot time. > That works for me. I will update it for the next release. FWIW, I rather liked Dan's idea of wrapping this under vm_debug=. We've got a zoo of boot options and it's really hard to _remember_ what does what. For this case, we're creating one that's only available under a specific debug option and I think it makes total sense to name the boot option accordingly. For now, I think it makes total sense to do vm_debug=all/off. If, in the future, we get more options, we can do things like slab does and do vm_debug=P (for Page poison) for this feature specifically. vm_debug = [KNL] Available with CONFIG_DEBUG_VM=y. May slow down boot speed, especially on larger- memory systems when enabled. off: turn off all runtime VM debug features all: turn on all debug features (default) _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm