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=-5.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,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 0ECCFC1975A for ; Wed, 25 Mar 2020 07:37:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D6F2020774 for ; Wed, 25 Mar 2020 07:37:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Qi0GCh+x" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726998AbgCYHhR (ORCPT ); Wed, 25 Mar 2020 03:37:17 -0400 Received: from us-smtp-delivery-74.mimecast.com ([216.205.24.74]:35990 "EHLO us-smtp-delivery-74.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726043AbgCYHhR (ORCPT ); Wed, 25 Mar 2020 03:37:17 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585121836; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=N/3tnkUCJ84ugchd9292obK8XYMkUQ1oS76eIfkU4vE=; b=Qi0GCh+x3KwoXiknQ+g+l+qyBOZ9m9bqHFQ/vY3ilQovVHgJNLlBCYNKbHMZbiWJ0Omeog sc32Vhg8fHE/1DZty2/nRCaHNQeiCBG2ncaYLqt6KJN6LZUDfabves7kKoI6Zs4BtEpVFp X1V513KEGZdZJErJvl4q7s6G9Cx15Ik= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-315-OZVwnALVNFGfH-Sy4dByRQ-1; Wed, 25 Mar 2020 03:37:12 -0400 X-MC-Unique: OZVwnALVNFGfH-Sy4dByRQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 7C3E713EA; Wed, 25 Mar 2020 07:37:10 +0000 (UTC) Received: from localhost (ovpn-12-88.pek2.redhat.com [10.72.12.88]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D1D3D108BF0F; Wed, 25 Mar 2020 07:37:09 +0000 (UTC) Date: Wed, 25 Mar 2020 15:37:07 +0800 From: Baoquan He To: "Aneesh Kumar K.V" Cc: linux-mm@kvack.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, Sachin Sant , dan.j.williams@intel.com Subject: Re: [PATCH] mm/sparse: Fix kernel crash with pfn_section_valid check Message-ID: <20200325073707.GI3039@MiWiFi-R3L-srv> References: <20200325031914.107660-1-aneesh.kumar@linux.ibm.com> <20200325070643.GH3039@MiWiFi-R3L-srv> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200325070643.GH3039@MiWiFi-R3L-srv> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/25/20 at 03:06pm, Baoquan He wrote: > On 03/25/20 at 08:49am, Aneesh Kumar K.V wrote: > > mm/sparse.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/mm/sparse.c b/mm/sparse.c > > index aadb7298dcef..3012d1f3771a 100644 > > --- a/mm/sparse.c > > +++ b/mm/sparse.c > > @@ -781,6 +781,8 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages, > > ms->usage = NULL; > > } > > memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr); > > + /* Mark the section invalid */ > > + ms->section_mem_map &= ~SECTION_HAS_MEM_MAP; > > Not sure if we should add checking in valid_section() or pfn_valid(), > e.g check ms->usage validation too. Otherwise, this fix looks good to > me. With SPASEMEM_VMEMAP enabled, we should do validation check on ms->usage before checking any subsection is valid. Since now we do have case in which ms->usage is released, people still try to check it. diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index f0a2c184eb9a..d79bd938852e 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -1306,6 +1306,8 @@ static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn) { int idx = subsection_map_index(pfn); + if (!ms->usage) + return 0; return test_bit(idx, ms->usage->subsection_map); } #else