From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751894AbdLAJmU (ORCPT ); Fri, 1 Dec 2017 04:42:20 -0500 Received: from mx2.suse.de ([195.135.220.15]:44511 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750872AbdLAJmR (ORCPT ); Fri, 1 Dec 2017 04:42:17 -0500 Date: Fri, 1 Dec 2017 10:42:15 +0100 From: Michal Hocko To: Dave Young Cc: linux-kernel@vger.kernel.org, pasha.tatashin@oracle.com, linux-mm@kvack.org, akpm@linux-foundation.org Subject: Re: [PATCH] mm: check pfn_valid first in zero_resv_unavail Message-ID: <20171201094215.aenoqa5jepdc3jd5@dhcp22.suse.cz> References: <20171130060431.GA2290@dhcp-128-65.nay.redhat.com> <20171130093521.3yxyq6xvo6zgaifc@dhcp22.suse.cz> <20171201085657.GA2291@dhcp-128-65.nay.redhat.com> <20171201091930.5ddygjl23owfovrz@dhcp22.suse.cz> <20171201092951.GA2943@dhcp-128-65.nay.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171201092951.GA2943@dhcp-128-65.nay.redhat.com> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 01-12-17 17:29:51, Dave Young wrote: > On 12/01/17 at 10:19am, Michal Hocko wrote: > > On Fri 01-12-17 16:56:57, Dave Young wrote: > > > On 11/30/17 at 10:35am, Michal Hocko wrote: > > [...] > > > > Can we exclude that range from the memblock allocator instead? E.g. what > > > > happens if somebody allocates from that range? > > > > > > It is a EFI BGRT image buffer provided by firmware, they are reserved > > > always and can not be used to allocate memory. > > > > Hmm, I see but I was actually suggesting to remove this range from the > > memblock allocator altogether (memblock_remove) as it shouldn't be there > > in the first place. > > Oh, I'm not sure because it is introduced as a way for efi to reserve > boot services areas to be persistent across kexec reboot. See > drivers/firmware/efi/efi.c: efi_mem_reserve(), BGRT is only one user > of it, there is esrt and maybe other users, I do not know if it is safe > :( Hmm, so it this range ever backed by a valid pfn? -- Michal Hocko SUSE Labs