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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 8B76AC433E0 for ; Tue, 5 Jan 2021 07:41:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3C3B121973 for ; Tue, 5 Jan 2021 07:41:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726993AbhAEHlk (ORCPT ); Tue, 5 Jan 2021 02:41:40 -0500 Received: from mx2.suse.de ([195.135.220.15]:37162 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726029AbhAEHlk (ORCPT ); Tue, 5 Jan 2021 02:41:40 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1609832453; h=from:from:reply-to: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=P7COg91NEwnP/uoCOSBzJuMmSS7WoPNptWSZsUU3f/o=; b=EgoV3I74xEMcKMjMn8KSvPeJlhAkzWHkNZaQLGiBRNeJIO6Alplk6EH2ruegnoHQvvBMgg 2Bqc9PoIiiuGaWSwqibh6awULQORFO22w9Za4LKdSFqgoiu0osr4d+0cdvodYvpqEHsLqx iitl2vtvJ3rH85xTolJbWwD8ByKKRKU= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 5993AAA35; Tue, 5 Jan 2021 07:40:53 +0000 (UTC) Date: Tue, 5 Jan 2021 08:40:52 +0100 From: Michal Hocko To: Dan Williams Cc: David Hildenbrand , Linux MM , LKML , Oscar Salvador Subject: Re: uninitialized pmem struct pages Message-ID: <20210105074052.GQ13207@dhcp22.suse.cz> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 04-01-21 21:33:06, Dan Williams wrote: > On Mon, Jan 4, 2021 at 7:59 AM Michal Hocko wrote: [...] > > 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 > > > > > I do wonder what hosts pfn_to_page(PHYS_PFN(0x6060000)) - is it actually > > > part of the actual altmap (i.e. > 0x6060000) or maybe even self-hosted? > > > > I am not really familiar with the pmem so I would need more assistance > > here. I've tried this (shot into the dark): > > crash> struct page.pgmap fffff8c600181800 > > pgmap = 0xfffff8c600181808 > > Does /proc/iomem show an active namespace in the range? Any tips how I dig that out from the crash dump? > You should be > able to skip ahead to the first pfn in that namespace to find the > first dev_pagemap. I would have expected pfn_to_online_page() to have > saved you here. This address range is section aligned. Well, the affected code in this case was end_pfn = min(start_pfn + nr_pages, zone_end_pfn(page_zone(pfn_to_page(start_pfn)))); where start_pfn was the first pfn of a memory section. This code was completely unaware of zone device or dev_pagemap like most others pfn walkers. It just wanted to get bounds for the zone but it stumbled over uninitialized zone/node. -- Michal Hocko SUSE Labs