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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 7854BC32792 for ; Mon, 30 Sep 2019 11:01:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 477F421855 for ; Mon, 30 Sep 2019 11:01:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1569841262; bh=eKtlC/QS9C5TpQ2Zwitjtpt/UtsVlMideLkWYLpkfe8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=cJ2ZZhks+KwJ6KqxoSdjHlJMtI1yALa6R4KzMqamwdD5s7HIEWPv88U/jWqQfNQqd 3hiTEPcx/BFaLFVCTLrS/xx8TaPpwfr59cHkudgE9pyuR48kL1UYy30o2rk1XjqfoC Jxy9Ub/pe9pHnTpseEzg7IdT3fsz5ONBogIGpnvA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730890AbfI3LBB (ORCPT ); Mon, 30 Sep 2019 07:01:01 -0400 Received: from mx2.suse.de ([195.135.220.15]:37506 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729415AbfI3LBB (ORCPT ); Mon, 30 Sep 2019 07:01:01 -0400 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 17D44AC7B; Mon, 30 Sep 2019 11:00:59 +0000 (UTC) Date: Mon, 30 Sep 2019 13:00:58 +0200 From: Michal Hocko To: Qian Cai Cc: akpm@linux-foundation.org, heiko.carstens@de.ibm.com, gor@linux.ibm.com, borntraeger@de.ibm.com, linux-s390@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/page_alloc: fix a crash in free_pages_prepare() Message-ID: <20190930110058.GB25306@dhcp22.suse.cz> References: <1569613623-16820-1-git-send-email-cai@lca.pw> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1569613623-16820-1-git-send-email-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 Fri 27-09-19 15:47:03, Qian Cai wrote: > On architectures like s390, arch_free_page() could mark the page unused > (set_page_unused()) and any access later would trigger a kernel panic. > Fix it by moving arch_free_page() after all possible accessing calls. > > Hardware name: IBM 2964 N96 400 (z/VM 6.4.0) > Krnl PSW : 0404e00180000000 0000000026c2b96e > (__free_pages_ok+0x34e/0x5d8) > R:0 T:1 IO:0 EX:0 Key:0 M:1 W:0 P:0 AS:3 CC:2 PM:0 RI:0 EA:3 > Krnl GPRS: 0000000088d43af7 0000000000484000 000000000000007c > 000000000000000f > 000003d080012100 000003d080013fc0 0000000000000000 > 0000000000100000 > 00000000275cca48 0000000000000100 0000000000000008 > 000003d080010000 > 00000000000001d0 000003d000000000 0000000026c2b78a > 000000002717fdb0 > Krnl Code: 0000000026c2b95c: ec1100b30659 risbgn %r1,%r1,0,179,6 > 0000000026c2b962: e32014000036 pfd 2,1024(%r1) > #0000000026c2b968: d7ff10001000 xc 0(256,%r1),0(%r1) > >0000000026c2b96e: 41101100 la %r1,256(%r1) > 0000000026c2b972: a737fff8 brctg %r3,26c2b962 > 0000000026c2b976: d7ff10001000 xc 0(256,%r1),0(%r1) > 0000000026c2b97c: e31003400004 lg %r1,832 > 0000000026c2b982: ebff1430016a asi 5168(%r1),-1 > Call Trace: > __free_pages_ok+0x16a/0x5d8) > memblock_free_all+0x206/0x290 > mem_init+0x58/0x120 > start_kernel+0x2b0/0x570 > startup_continue+0x6a/0xc0 > INFO: lockdep is turned off. > Last Breaking-Event-Address: > __free_pages_ok+0x372/0x5d8 > Kernel panic - not syncing: Fatal exception: panic_on_oops > 00: HCPGIR450W CP entered; disabled wait PSW 00020001 80000000 00000000 > 26A2379C > > Signed-off-by: Qian Cai Unless I am missing something Fixes: 8823b1dbc05f ("mm/page_poison.c: enable PAGE_POISONING as a separate option") Fixes: 6471384af2a6 ("mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options") Cc: stable With the comment discussed later in the thread Acked-by: Michal Hocko > --- > mm/page_alloc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 3334a769eb91..a54ff6a60649 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1175,11 +1175,11 @@ static __always_inline bool free_pages_prepare(struct page *page, > debug_check_no_obj_freed(page_address(page), > PAGE_SIZE << order); > } > - arch_free_page(page, order); > if (want_init_on_free()) > kernel_init_free_pages(page, 1 << order); > > kernel_poison_pages(page, 1 << order, 0); > + arch_free_page(page, order); > if (debug_pagealloc_enabled()) > kernel_map_pages(page, 1 << order, 0); > > -- > 1.8.3.1 > -- Michal Hocko SUSE Labs