From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B2539C43387 for ; Thu, 20 Dec 2018 09:22:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7EC1B217D8 for ; Thu, 20 Dec 2018 09:22:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1545297728; bh=0SzFpg0Czr5ZqcIKaHUhnmdV6p2DVbZpuxjDCPuxrPk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=SxaxfVbVhxagCsW9BnoVY2CCeWDcnLS7UsiKFTXFGVD0sSK6G2drL7YOWzwv58b7s B/isGKrWreVJAR1Z/adwYATwvBpJKleV5VK9iIlIA8O8I76KfSFsYSv4ZeGwFL41pe z/leyaXZUZRTXiMRvNsQVpq9bemn7eatJzDa5tns= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731265AbeLTJWH (ORCPT ); Thu, 20 Dec 2018 04:22:07 -0500 Received: from mx2.suse.de ([195.135.220.15]:52556 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1731250AbeLTJWE (ORCPT ); Thu, 20 Dec 2018 04:22:04 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id D949AB005; Thu, 20 Dec 2018 09:22:02 +0000 (UTC) Date: Thu, 20 Dec 2018 10:22:02 +0100 From: Michal Hocko To: Qian Cai Cc: akpm@linux-foundation.org, Pavel.Tatashin@microsoft.com, mingo@kernel.org, hpa@zytor.com, mgorman@techsingularity.net, tglx@linutronix.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/page_owner: fix for deferred struct page init Message-ID: <20181220092202.GD14234@dhcp22.suse.cz> References: <20181220060303.38686-1-cai@lca.pw> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181220060303.38686-1-cai@lca.pw> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 20-12-18 01:03:03, Qian Cai wrote: > When booting a system with "page_owner=on", > > start_kernel > page_ext_init > invoke_init_callbacks > init_section_page_ext > init_page_owner > init_early_allocated_pages > init_zones_in_node > init_pages_in_zone > lookup_page_ext > page_to_nid > > The issue here is that page_to_nid() will not work since some page > flags have no node information until later in page_alloc_init_late() due > to DEFERRED_STRUCT_PAGE_INIT. Hence, it could trigger an out-of-bounds > access with an invalid nid. > > [ 8.666047] UBSAN: Undefined behaviour in ./include/linux/mm.h:1104:50 > [ 8.672603] index 7 is out of range for type 'zone [5]' > > Also, kernel will panic since flags were poisoned earlier with, > > CONFIG_DEBUG_VM_PGFLAGS=y > CONFIG_NODE_NOT_IN_PAGE_FLAGS=n > > start_kernel > setup_arch > pagetable_init > paging_init > sparse_init > sparse_init_nid > memblock_alloc_try_nid_raw > > Although later it tries to set page flags for pages in reserved bootmem > regions, > > mm_init > mem_init > memblock_free_all > free_low_memory_core_early > reserve_bootmem_region > > there could still have some freed pages from the page allocator but yet > to be initialized due to DEFERRED_STRUCT_PAGE_INIT. It have already been > dealt with a bit in page_ext_init(). Is there any reason why we cannot postpone page_ext initialization to after all the memory is initialized? -- Michal Hocko SUSE Labs