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 9088EC43331 for ; Mon, 4 Jan 2021 16:11:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6C0BE20578 for ; Mon, 4 Jan 2021 16:11:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729417AbhADQLB (ORCPT ); Mon, 4 Jan 2021 11:11:01 -0500 Received: from mx2.suse.de ([195.135.220.15]:54636 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728289AbhADQAT (ORCPT ); Mon, 4 Jan 2021 11:00:19 -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=1609775972; 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=W2TfnFOGUvyeB9YoMIAEOhEsC9AvA3aFr1YVlOG6Ieo=; b=VJgn/Eu4KPx87UZLuqWg8tmdI8kcJ/JImCeLXKaPdpc4JftuKTDkHlvTEqMsygz1D4fbaj 8j/i4kyaijW3kiNLgIIVEcVzTm0nqy0TQ7HiUwij9ePrn5ShGl5Q16LAkEQa4hBTfrdo0z TucpSifh6L8nSmbrg1XfguYnfeU88HM= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 8CD29AE2B; Mon, 4 Jan 2021 15:59:32 +0000 (UTC) Date: Mon, 4 Jan 2021 16:59:31 +0100 From: Michal Hocko To: David Hildenbrand Cc: Dan Williams , linux-mm@kvack.org, LKML , Oscar Salvador Subject: Re: uninitialized pmem struct pages Message-ID: <20210104155931.GN13207@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> 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 16:43:49, David Hildenbrand wrote: > On 04.01.21 16:33, Michal Hocko wrote: > > On Mon 04-01-21 16:15:23, David Hildenbrand wrote: > >> On 04.01.21 16:10, Michal Hocko wrote: > > [...] > >> Do the physical addresses you see fall into the same section as boot > >> memory? Or what's around these addresses? > > > > Yes I am getting a garbage for the first struct page belonging to the > > pmem section [1] > > [ 0.020161] ACPI: SRAT: Node 0 PXM 0 [mem 0x100000000-0x603fffffff] > > [ 0.020163] ACPI: SRAT: Node 4 PXM 4 [mem 0x6060000000-0x11d5fffffff] non-volatile > > > > The pfn without the initialized struct page is 0x6060000. This is a > > first pfn in a section. > > Okay, so we're not dealing with the "early section" mess I described, > different story. > > Due to [1], is_mem_section_removable() called > pfn_to_page(PHYS_PFN(0x6060000)). page_zone(page) made it crash, as not > initialized. Exactly! > 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 > 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 crash> struct -x dev_pagemap 0xfffff8c600181808 struct dev_pagemap { altmap = { base_pfn = 0xfffff8c600181808, end_pfn = 0xfffff8c600181808, reserve = 0x0, free = 0x0, align = 0x0, alloc = 0xffffffff }, res = { start = 0x0, end = 0xfffffc0000000, name = 0xfffff8c600181848 "H\030\030", flags = 0xfffff8c600181848, desc = 0x0, parent = 0x0, sibling = 0x0, child = 0xffffffff }, ref = 0x0, internal_ref = { count = { counter = 0xfffffc0000000 }, percpu_count_ptr = 0xfffff8c600181888, release = 0xfffff8c600181888, confirm_switch = 0x0, force_atomic = 0x0, allow_reinit = 0x0, rcu = { next = 0x0, func = 0xffffffff } }, done = { done = 0x0, wait = { lock = { { rlock = { raw_lock = { { val = { counter = 0xc0000000 }, { locked = 0x0, pending = 0x0 }, { locked_pending = 0x0, tail = 0xc000 } } } } } }, head = { next = 0xfffff8c6001818c8, prev = 0xfffff8c6001818c8 } } }, dev = 0x0, type = 0, flags = 0x0, ops = 0x0 } Not sure whether this is of any use. > If it's not self-hosted, initializing the relevant memmaps should work > just fine I guess. Otherwise things get more complicated. -- Michal Hocko SUSE Labs