From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S942607AbdAJAhs (ORCPT ); Mon, 9 Jan 2017 19:37:48 -0500 Received: from mx1.redhat.com ([209.132.183.28]:36160 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S939690AbdAJAho (ORCPT ); Mon, 9 Jan 2017 19:37:44 -0500 Date: Tue, 10 Jan 2017 08:37:35 +0800 From: Dave Young To: Matt Fleming Cc: Nicolai Stange , Ard Biesheuvel , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, Mika =?iso-8859-1?Q?Penttil=E4?= , Andrew Morton , linux-mm@kvack.org, Vlastimil Babka , Michal Hocko , Mel Gorman Subject: Re: [PATCH v2 2/2] efi: efi_mem_reserve(): don't reserve through memblock after mm_init() Message-ID: <20170110003735.GA2809@dhcp-128-65.nay.redhat.com> References: <20161222102340.2689-1-nicstange@gmail.com> <20161222102340.2689-2-nicstange@gmail.com> <20170105091242.GA11021@dhcp-128-65.nay.redhat.com> <20170109114400.GF16838@codeblueprint.co.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170109114400.GF16838@codeblueprint.co.uk> User-Agent: Mutt/1.7.1 (2016-10-04) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Tue, 10 Jan 2017 00:37:45 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/09/17 at 11:44am, Matt Fleming wrote: > On Thu, 05 Jan, at 05:12:42PM, Dave Young wrote: > > On 12/22/16 at 11:23am, Nicolai Stange wrote: > > > Before invoking the arch specific handler, efi_mem_reserve() reserves > > > the given memory region through memblock. > > > > > > efi_mem_reserve() can get called after mm_init() though -- through > > > efi_bgrt_init(), for example. After mm_init(), memblock is dead and should > > > not be used anymore. > > > > It did not fail during previous test so we did not catch this bug, if memblock > > can not be used after mm_init(), IMHO it should fail instead of silently succeed. > > This must literally be the fifth time or so that I've been caught out > by this over the years because there's no hard error if you call the > memblock code after slab and co. are up. > > MM folks, is there some way to catch these errors without requiring > the sprinkling of slab_is_available() everywhere? > > > Matt, can we move the efi_mem_reserve to earlier code for example in > > efi_memblock_x86_reserve_range just after reserving the memmap? > > No, it *needs* to be callable from efi_bgrt_init(), because you only > want to reserve those regions if you have the BGRT driver available. It is true that it depends on acpi init, I was wondering if bgrt parsing can be moved to early acpi code. But anyway I'm not sure it is doable and worth. Thanks Dave