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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 66829C4CECE for ; Mon, 14 Oct 2019 09:06:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 469AE207FF for ; Mon, 14 Oct 2019 09:06:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730670AbfJNJGB (ORCPT ); Mon, 14 Oct 2019 05:06:01 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45300 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730605AbfJNJGA (ORCPT ); Mon, 14 Oct 2019 05:06:00 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 962863082E42; Mon, 14 Oct 2019 09:05:59 +0000 (UTC) Received: from [10.36.117.10] (ovpn-117-10.ams2.redhat.com [10.36.117.10]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6C47860BE2; Mon, 14 Oct 2019 09:05:55 +0000 (UTC) Subject: Re: [PATCH v6 01/10] mm/memunmap: Don't access uninitialized memmap in memunmap_pages() To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, x86@kernel.org, "Aneesh Kumar K.V" , Dan Williams , Andrew Morton , Jason Gunthorpe , Logan Gunthorpe , Ira Weiny References: <20191006085646.5768-1-david@redhat.com> <20191006085646.5768-2-david@redhat.com> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: Date: Mon, 14 Oct 2019 11:05:54 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.0 MIME-Version: 1.0 In-Reply-To: <20191006085646.5768-2-david@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Mon, 14 Oct 2019 09:06:00 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06.10.19 10:56, David Hildenbrand wrote: > From: "Aneesh Kumar K.V" > > With an altmap, the memmap falling into the reserved altmap space are > not initialized and, therefore, contain a garbage NID and a garbage > zone. Make sure to read the NID/zone from a memmap that was initialzed. > > This fixes a kernel crash that is observed when destroying a namespace: > > [ 81.356173] kernel BUG at include/linux/mm.h:1107! > cpu 0x1: Vector: 700 (Program Check) at [c000000274087890] > pc: c0000000004b9728: memunmap_pages+0x238/0x340 > lr: c0000000004b9724: memunmap_pages+0x234/0x340 > ... > pid = 3669, comm = ndctl > kernel BUG at include/linux/mm.h:1107! > [c000000274087ba0] c0000000009e3500 devm_action_release+0x30/0x50 > [c000000274087bc0] c0000000009e4758 release_nodes+0x268/0x2d0 > [c000000274087c30] c0000000009dd144 device_release_driver_internal+0x174/0x240 > [c000000274087c70] c0000000009d9dfc unbind_store+0x13c/0x190 > [c000000274087cb0] c0000000009d8a24 drv_attr_store+0x44/0x60 > [c000000274087cd0] c0000000005a7470 sysfs_kf_write+0x70/0xa0 > [c000000274087d10] c0000000005a5cac kernfs_fop_write+0x1ac/0x290 > [c000000274087d60] c0000000004be45c __vfs_write+0x3c/0x70 > [c000000274087d80] c0000000004c26e4 vfs_write+0xe4/0x200 > [c000000274087dd0] c0000000004c2a6c ksys_write+0x7c/0x140 > [c000000274087e20] c00000000000bbd0 system_call+0x5c/0x68 > > Cc: Dan Williams > Cc: Andrew Morton > Cc: Jason Gunthorpe > Cc: Logan Gunthorpe > Cc: Ira Weiny > Signed-off-by: Aneesh Kumar K.V > [ minimze code changes, rephrase description ] > Signed-off-by: David Hildenbrand > --- > mm/memremap.c | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) > > diff --git a/mm/memremap.c b/mm/memremap.c > index 557e53c6fb46..8c2fb44c3b4d 100644 > --- a/mm/memremap.c > +++ b/mm/memremap.c > @@ -123,6 +123,7 @@ static void dev_pagemap_cleanup(struct dev_pagemap *pgmap) > void memunmap_pages(struct dev_pagemap *pgmap) > { > struct resource *res = &pgmap->res; > + struct page *first_page; > unsigned long pfn; > int nid; > > @@ -131,14 +132,16 @@ void memunmap_pages(struct dev_pagemap *pgmap) > put_page(pfn_to_page(pfn)); > dev_pagemap_cleanup(pgmap); > > + /* make sure to access a memmap that was actually initialized */ > + first_page = pfn_to_page(pfn_first(pgmap)); > + > /* pages are dead and unused, undo the arch mapping */ > - nid = page_to_nid(pfn_to_page(PHYS_PFN(res->start))); > + nid = page_to_nid(first_page); > > mem_hotplug_begin(); > if (pgmap->type == MEMORY_DEVICE_PRIVATE) { > - pfn = PHYS_PFN(res->start); > - __remove_pages(page_zone(pfn_to_page(pfn)), pfn, > - PHYS_PFN(resource_size(res)), NULL); > + __remove_pages(page_zone(first_page), PHYS_PFN(res->start), > + PHYS_PFN(resource_size(res)), NULL); > } else { > arch_remove_memory(nid, res->start, resource_size(res), > pgmap_altmap(pgmap)); > @Andrew, can you add Fixes: 2c2a5af6fed2 ("mm, memory_hotplug: add nid parameter to arch_remove_memory") (which basically introduced the nid = page_to_nid(first_page)) The "page_zone(pfn_to_page(pfn)" was introduced by 69324b8f4833 ("mm, devm_memremap_pages: add MEMORY_DEVICE_PRIVATE support"), however, I think we will never have driver reserved memory with MEMORY_DEVICE_PRIVATE (no altmap AFAIKS). Also, I think Cc: stable@vger.kernel.org # v5.0+ makes sense. -- Thanks, David / dhildenb