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=-11.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 6CF43C43444 for ; Thu, 3 Jan 2019 11:51:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 13F6F21479 for ; Thu, 3 Jan 2019 11:51:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546516280; bh=5e8TcBgEVqT1VyEWEWrdHtKdZEkqWwaKHnFnPIu78no=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=aRcaMyeTLbQV+EeUCEB0vO8ZFgW9sJ+iCI2ubTLKRKS+QDQVIzqnXuB+yWtrEFVn7 tV0YOZY60lItgj2agH4ICGu1nS0Tt2CgS92UjgV4JsfoJ1qKNNuEgl3QoiqHprbYNs 5o/qan8n+ag/hw0dFLoqqEJaygiXdkNQ42+ckQzk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730510AbfACLvS (ORCPT ); Thu, 3 Jan 2019 06:51:18 -0500 Received: from mx2.suse.de ([195.135.220.15]:60618 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726345AbfACLvS (ORCPT ); Thu, 3 Jan 2019 06:51:18 -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 D3B4CACAE; Thu, 3 Jan 2019 11:51:15 +0000 (UTC) Date: Thu, 3 Jan 2019 12:51:14 +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, iamjoonsoo.kim@lge.com, yang.shi@linaro.org, tglx@linutronix.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] mm/page_owner: fix for deferred struct page init Message-ID: <20190103115114.GL31793@dhcp22.suse.cz> References: <20181220185031.43146-1-cai@lca.pw> <20181220203156.43441-1-cai@lca.pw> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181220203156.43441-1-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 15:31:56, 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(). > > * Take into account DEFERRED_STRUCT_PAGE_INIT. > */ > if (early_pfn_to_nid(pfn) != nid) > continue; > > However, it did not handle it well in init_pages_in_zone() which end up > calling page_to_nid(). > > [ 11.917212] page:ffffea0004200000 is uninitialized and poisoned > [ 11.917220] raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff > ffffffffffffffff > [ 11.921745] raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff > ffffffffffffffff > [ 11.924523] page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p)) > [ 11.926498] page_owner info is not active (free page?) > [ 12.329560] kernel BUG at include/linux/mm.h:990! > [ 12.337632] RIP: 0010:init_page_owner+0x486/0x520 > > Since there is no other routines depend on page_ext_init() in > start_kernel(), just move it after page_alloc_init_late() to ensure that > there is no deferred pages need to de dealt with. If deselected > DEFERRED_STRUCT_PAGE_INIT, it is still better to call page_ext_init() > earlier, so page owner could catch more early page allocation call > sites. This gives us a good compromise between catching good and bad > call sites (See the v1 patch [1]) in case of DEFERRED_STRUCT_PAGE_INIT. > > [1] https://lore.kernel.org/lkml/20181220060303.38686-1-cai@lca.pw/ > > Fixes: fe53ca54270 (mm: use early_pfn_to_nid in page_ext_init) > Suggested-by: Michal Hocko > Signed-off-by: Qian Cai > --- > > v3: still call page_ext_init() earlier if DEFERRED_STRUCT_PAGE_INIT=n. > > v2: postpone page_ext_init() to after page_alloc_init_late(). > > init/main.c | 5 +++++ > mm/page_ext.c | 3 +-- > 2 files changed, 6 insertions(+), 2 deletions(-) > > diff --git a/init/main.c b/init/main.c > index 2b7b7fe173c9..5d9904370f76 100644 > --- a/init/main.c > +++ b/init/main.c > @@ -696,7 +696,9 @@ asmlinkage __visible void __init start_kernel(void) > initrd_start = 0; > } > #endif > +#ifndef CONFIG_DEFERRED_STRUCT_PAGE_INIT > page_ext_init(); > +#endif > kmemleak_init(); > setup_per_cpu_pageset(); > numa_policy_init(); > @@ -1147,6 +1149,9 @@ static noinline void __init kernel_init_freeable(void) > sched_init_smp(); > > page_alloc_init_late(); > +#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT > + page_ext_init(); > +#endif > > do_basic_setup(); Is this really necessary? Why cannot we simply postpone page_ext_init unconditioanally? > > diff --git a/mm/page_ext.c b/mm/page_ext.c > index ae44f7adbe07..d76fd51e312a 100644 > --- a/mm/page_ext.c > +++ b/mm/page_ext.c > @@ -399,9 +399,8 @@ void __init page_ext_init(void) > * -------------pfn--------------> > * N0 | N1 | N2 | N0 | N1 | N2|.... > * > - * Take into account DEFERRED_STRUCT_PAGE_INIT. > */ > - if (early_pfn_to_nid(pfn) != nid) > + if (pfn_to_nid(pfn) != nid) > continue; > if (init_section_page_ext(pfn, nid)) > goto oom; Also this doesn't seem to be related, right? -- Michal Hocko SUSE Labs