From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f70.google.com (mail-it0-f70.google.com [209.85.214.70]) by kanga.kvack.org (Postfix) with ESMTP id E48F86B0003 for ; Tue, 19 Jun 2018 09:51:33 -0400 (EDT) Received: by mail-it0-f70.google.com with SMTP id p130-v6so239115itp.2 for ; Tue, 19 Jun 2018 06:51:33 -0700 (PDT) Received: from userp2130.oracle.com (userp2130.oracle.com. [156.151.31.86]) by mx.google.com with ESMTPS id k3-v6si7861448jad.99.2018.06.19.06.51.32 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 19 Jun 2018 06:51:32 -0700 (PDT) Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.22/8.16.0.22) with SMTP id w5JDioar083036 for ; Tue, 19 Jun 2018 13:51:31 GMT Received: from aserv0022.oracle.com (aserv0022.oracle.com [141.146.126.234]) by userp2130.oracle.com with ESMTP id 2jmt01g9g9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Tue, 19 Jun 2018 13:51:31 +0000 Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by aserv0022.oracle.com (8.14.4/8.14.4) with ESMTP id w5JDpT9A029227 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Tue, 19 Jun 2018 13:51:29 GMT Received: from abhmp0012.oracle.com (abhmp0012.oracle.com [141.146.116.18]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id w5JDpTKE028784 for ; Tue, 19 Jun 2018 13:51:29 GMT Received: by mail-oi0-f53.google.com with SMTP id i205-v6so18215294oib.1 for ; Tue, 19 Jun 2018 06:51:29 -0700 (PDT) MIME-Version: 1.0 References: <20171117014601.31606-1-pasha.tatashin@oracle.com> <20171121072416.v77vu4osm2s4o5sq@dhcp22.suse.cz> In-Reply-To: From: Pavel Tatashin Date: Tue, 19 Jun 2018 09:50:52 -0400 Message-ID: Subject: Re: [PATCH v1] mm: relax deferred struct page requirements Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: jslaby@suse.cz Cc: mhocko@kernel.org, Steven Sistare , Daniel Jordan , benh@kernel.crashing.org, paulus@samba.org, Andrew Morton , kirill.shutemov@linux.intel.com, Reza Arbab , schwidefsky@de.ibm.com, Heiko Carstens , x86@kernel.org, LKML , tglx@linutronix.de, linuxppc-dev@lists.ozlabs.org, Linux Memory Management List , linux-s390@vger.kernel.org, mgorman@techsingularity.net On Sat, Jun 16, 2018 at 4:04 AM Jiri Slaby wrote: > > On 11/21/2017, 08:24 AM, Michal Hocko wrote: > > On Thu 16-11-17 20:46:01, Pavel Tatashin wrote: > >> There is no need to have ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT, > >> as all the page initialization code is in common code. > >> > >> Also, there is no need to depend on MEMORY_HOTPLUG, as initialization code > >> does not really use hotplug memory functionality. So, we can remove this > >> requirement as well. > >> > >> This patch allows to use deferred struct page initialization on all > >> platforms with memblock allocator. > >> > >> Tested on x86, arm64, and sparc. Also, verified that code compiles on > >> PPC with CONFIG_MEMORY_HOTPLUG disabled. > > > > There is slight risk that we will encounter corner cases on some > > architectures with weird memory layout/topology > > Which x86_32-pae seems to be. Many bad page state errors are emitted > during boot when this patch is applied: Hi Jiri, Thank you for reporting this bug. Because 32-bit systems are limited in the maximum amount of physical memory, they don't need deferred struct pages. So, we can add depends on 64BIT to DEFERRED_STRUCT_PAGE_INIT in mm/Kconfig. However, before we do this, I want to try reproducing this problem and root cause it, as it might expose a general problem that is not 32-bit specific. Thank you, Pavel