From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755480AbcHXCCq (ORCPT ); Tue, 23 Aug 2016 22:02:46 -0400 Received: from mail-bn3nam01on0099.outbound.protection.outlook.com ([104.47.33.99]:45815 "EHLO NAM01-BN3-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755226AbcHXCCp (ORCPT ); Tue, 23 Aug 2016 22:02:45 -0400 X-Greylist: delayed 8102 seconds by postgrey-1.27 at vger.kernel.org; Tue, 23 Aug 2016 22:02:45 EDT From: "Kani, Toshimitsu" To: "akpm@linux-foundation.org" CC: "dan.j.williams@intel.com" , "Mulumudi, Abhilash Kumar" , "linux-kernel@vger.kernel.org" , "ard.biesheuvel@linaro.org" , "linux-nvdimm@ml01.01.org" , "brian.starkey@arm.com" Subject: Re: [PATCH] memremap: Fix NULL pointer BUG in get_zone_device_page() Thread-Topic: [PATCH] memremap: Fix NULL pointer BUG in get_zone_device_page() Thread-Index: AQHR/W5ZePHh0bI7qkGTM3px2vEum6BXAs4AgAAL2wA= Date: Tue, 23 Aug 2016 21:25:09 +0000 Message-ID: <1471987482.32015.111.camel@hpe.com> References: <1471977800-12688-1-git-send-email-toshi.kani@hpe.com> <20160823134216.8f8e8944581fe1ae202377d1@linux-foundation.org> In-Reply-To: <20160823134216.8f8e8944581fe1ae202377d1@linux-foundation.org> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: spf=none (sender IP is ) smtp.mailfrom=toshi.kani@hpe.com; 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spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="utf-8" Content-ID: <468C953341858449A80409F3E3CA0001@NAMPRD84.PROD.OUTLOOK.COM> MIME-Version: 1.0 X-OriginatorOrg: hpe.com X-MS-Exchange-CrossTenant-originalarrivaltime: 23 Aug 2016 21:25:09.0178 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 105b2061-b669-4b31-92ac-24d304d195dc X-MS-Exchange-Transport-CrossTenantHeadersStamped: CS1PR84MB0005 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id u7O22ob0027050 On Tue, 2016-08-23 at 13:42 -0700, Andrew Morton wrote: > On Tue, 23 Aug 2016 12:43:20 -0600 Toshi Kani > wrote: > > > > > The following BUG was observed while starting up KVM with nvdimm > > device as memory-backend-file to /dev/dax. > > > >  BUG: unable to handle kernel NULL pointer dereference at > > 0000000000000008 > > > > ... > > > > devm_memremap_pages() calls for_each_device_pfn() to walk through > > all pfns in page_map.  pfn_first(), however, returns a wrong pfn > > that leaves page->pgmap uninitialized. > > > > Since arch_add_memory() has set up direct mappings to the NVDIMM > > range with altmap, pfn_first() should not modify the start pfn. > > Change pfn_first() to simply return pfn of res->start. > > Which kernel version(s) do you think need fixing? The fix applies to v4.5 and newer versions. Thanks, -Toshi