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=-7.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 B05CBC433DB for ; Tue, 5 Jan 2021 09:58:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7050C20739 for ; Tue, 5 Jan 2021 09:58:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728488AbhAEJ5x (ORCPT ); Tue, 5 Jan 2021 04:57:53 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:40964 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727860AbhAEJ5w (ORCPT ); Tue, 5 Jan 2021 04:57:52 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1609840586; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=iSoCoG28BB3krzJrBO/as9WWlyGiL/7dmvac6i2JgK0=; b=ZICvsoicbQ2VvMc+kox3daFFL8iYYGjJLP8k4Hc4dQR+X0f+dMhndkG83sHWykREBFXhiV OMqDP2kQFB/mYxwOoBbOLpU/F7T+yZjmExUFoH+mWtxEA6Bk5K5OJ5Xw+OMCA/dKvD9O7Y /CQgGTpUhovkZe+SXEh/62CWb6Cc5rI= 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-272-Vz0ly2cJPByUxjFY3U60EQ-1; Tue, 05 Jan 2021 04:56:24 -0500 X-MC-Unique: Vz0ly2cJPByUxjFY3U60EQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 512F815734; Tue, 5 Jan 2021 09:56:23 +0000 (UTC) Received: from [10.36.114.117] (ovpn-114-117.ams2.redhat.com [10.36.114.117]) by smtp.corp.redhat.com (Postfix) with ESMTP id 429A227C4E; Tue, 5 Jan 2021 09:56:22 +0000 (UTC) Subject: Re: uninitialized pmem struct pages To: Michal Hocko Cc: Dan Williams , linux-mm@kvack.org, LKML , Oscar Salvador References: <20210104100323.GC13207@dhcp22.suse.cz> <033e1cd6-9762-5de6-3e88-47d3038fda7f@redhat.com> <20210104142624.GI13207@dhcp22.suse.cz> <23a4eea2-9fdb-fd1d-ee92-9cd8ac6e8f41@redhat.com> <20210104151005.GK13207@dhcp22.suse.cz> <26db2c3e-10c7-c6e3-23f7-21eb5101b31a@redhat.com> <20210104153300.GL13207@dhcp22.suse.cz> <20210104155931.GN13207@dhcp22.suse.cz> <20210105074459.GR13207@dhcp22.suse.cz> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: Date: Tue, 5 Jan 2021 10:56:21 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.5.0 MIME-Version: 1.0 In-Reply-To: <20210105074459.GR13207@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05.01.21 08:44, Michal Hocko wrote: > On Mon 04-01-21 17:30:48, David Hildenbrand wrote: >>>> Let's assume this is indeed a reserved pfn in the altmap. What's the >>>> actual address of the memmap? >>> >>> Not sure what exactly you are asking for but crash says >>> crash> kmem -p 6060000 >>> PAGE PHYSICAL MAPPING INDEX CNT FLAGS >>> fffff8c600181800 6060000 0 0 0 fffffc0000000 >> >> ^ this looks like it was somewhat initialized. All flags zero, nid/zone >> set to -1 (wild guess) and thus the crash? weird > > Yes that made me scratch my head as well. My best guess would be that this is indeed part of the altmap reserve with a memmap on the altmap. Maybe these values are just leftovers on the PMEM device (e.g., from older kernels)? In the kernel, I cannot find anything that would initialize node/zone to -1 only. @Dan: Will get_dev_pagemap() return a valid dev_pagemap for pfns falling into the altmap reserved region? I think we should also initialize the memmap of the altmap reserved region somewhow. -- Thanks, David / dhildenb