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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, 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 AE288C2D0E5 for ; Fri, 27 Mar 2020 16:28:14 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 733CC20658 for ; Fri, 27 Mar 2020 16:28:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=intel-com.20150623.gappssmtp.com header.i=@intel-com.20150623.gappssmtp.com header.b="fw4vZ9o6" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 733CC20658 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id AC0126B000E; Fri, 27 Mar 2020 12:28:13 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A70F26B0010; Fri, 27 Mar 2020 12:28:13 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 986066B0032; Fri, 27 Mar 2020 12:28:13 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0061.hostedemail.com [216.40.44.61]) by kanga.kvack.org (Postfix) with ESMTP id 7D89A6B000E for ; Fri, 27 Mar 2020 12:28:13 -0400 (EDT) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 4F92F180AD811 for ; Fri, 27 Mar 2020 16:28:13 +0000 (UTC) X-FDA: 76641674466.20.card63_47b6d30277532 X-HE-Tag: card63_47b6d30277532 X-Filterd-Recvd-Size: 6504 Received: from mail-ed1-f65.google.com (mail-ed1-f65.google.com [209.85.208.65]) by imf45.hostedemail.com (Postfix) with ESMTP for ; Fri, 27 Mar 2020 16:28:12 +0000 (UTC) Received: by mail-ed1-f65.google.com with SMTP id cf14so11876846edb.13 for ; Fri, 27 Mar 2020 09:28:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=9DDvHtu2LPjFPTk6N1lekFV2ShYbYm5F3D1HLZEOy4c=; b=fw4vZ9o6IO+HeqP3Xok6kSfraOxkKRu3PTNnrtA1xuBEpKJw4E2lOL0cwe6R5C4/fS RhoOsxRVFEQ355RtKB3injRaQbeTDEMKkjGAXvMZTpncOv8V7sOpzZRls2ppexvsVyje 8x3ynqj+MMtcZV9eDQORFww/0X7TksNVf8vHCgQK6tgnV9ImVXB0dqW03mf9gZdRHEQi 9hPZQZLkYoG4j9gDWdgvLfOZNYWWH/kP7Ehqhdjt1+Mi5Qn90OXtTq6WURD/sChECIal D3e0+PY74OGxeKZUWDQx84QNiXzOKPB2pi2qAoCtUnVq+R4rydI8B2RaJ3TV2PtPsSOd TQsA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=9DDvHtu2LPjFPTk6N1lekFV2ShYbYm5F3D1HLZEOy4c=; b=NLkFi+vDygP0MOyLt4vVSwomS9pTcVKX8THgqtHAq2CkAjoFky8aJib8pAbjRQbNS/ vL1Kf3Y2nKd+cB8Oefj+gh0NpEEQ96DJRFqJxOWA9cTSCi0VAzx7Xq7FHyGyzWJbKFKP +aTyZXPlrE6Iy+KsyONisEGQBcZ/lMLyucj3mOdvyoTUFL+yG6lMdyShkWnHyXyOB7zl i9MyxqWg6cdWIpKIv+FLgys9W5+Uyx6Wd399MQU3sMx36NHoRap1ixcrcmPCOXnEIhen PwVq1i5LJb1JN6kQGNaTaOhwUZjCFnaZ4nLAdgl+zVwqViN6EJtIvr+XkT7BS9WMA+7B bocA== X-Gm-Message-State: ANhLgQ0zdPuSByxzzHC16wVUWzIPCCzd1Fg8/FFiMB53p9Acs2LUssCg uri9MA5syNY6ZbkIzYCvYVaS4DamrA0nX7kgkbQOOQ== X-Google-Smtp-Source: ADFU+vv9x1cRXR5JTTiwUKkMwnERnkbjfXRnFDDpWIPM5Fjuj1B/ZA0jL9dsfDKbMCnmWg8krWLCIRJeGHd6OtlGNmU= X-Received: by 2002:aa7:d7c7:: with SMTP id e7mr13903000eds.296.1585326491184; Fri, 27 Mar 2020 09:28:11 -0700 (PDT) MIME-Version: 1.0 References: <20200128093542.6908-1-david@redhat.com> <20200327074718.GT27965@dhcp22.suse.cz> <8c74afdc-98cb-dd48-c516-ff6e8b59d598@redhat.com> In-Reply-To: <8c74afdc-98cb-dd48-c516-ff6e8b59d598@redhat.com> From: Dan Williams Date: Fri, 27 Mar 2020 09:28:00 -0700 Message-ID: Subject: Re: [PATCH v1] drivers/base/memory.c: indicate all memory blocks as removable To: David Hildenbrand Cc: Michal Hocko , Linux Kernel Mailing List , Linux MM , Greg Kroah-Hartman , "Rafael J. Wysocki" , Andrew Morton , powerpc-utils-devel@googlegroups.com, util-linux@vger.kernel.org, Badari Pulavarty , Nathan Fontenot , Robert Jennings , Heiko Carstens , Karel Zak , "Scargall, Steve" Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Mar 27, 2020 at 2:00 AM David Hildenbrand wrote: > > On 27.03.20 08:47, Michal Hocko wrote: > > On Thu 26-03-20 23:24:08, Dan Williams wrote: > > [...] > >> David, Andrew, > >> > >> I'd like to recommend this patch for -stable as it likely (test > >> underway) solves this crash report from Steve: > >> > >> [ 148.796036] page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p)) > >> [ 148.796074] ------------[ cut here ]------------ > >> [ 148.796098] kernel BUG at include/linux/mm.h:1087! > >> [ 148.796126] invalid opcode: 0000 [#1] SMP NOPTI > >> [ 148.796146] CPU: 63 PID: 5471 Comm: lsmem Not tainted 5.5.10-200.fc31.x8= > >> 6_64+debug #1 > >> [ 148.796173] Hardware name: Intel Corporation S2600WFD/S2600WFD, BIOS SE5= > >> C620.86B.02.01.0010.010620200716 01/06/2020 > >> [ 148.796212] RIP: 0010:is_mem_section_removable+0x1a4/0x1b0 > >> [ 148.796561] Call Trace: > >> [ 148.796591] removable_show+0x6e/0xa0 > >> [ 148.796608] dev_attr_show+0x19/0x40 > >> [ 148.796625] sysfs_kf_seq_show+0xa9/0x100 > >> [ 148.796640] seq_read+0xd5/0x450 > >> [ 148.796657] vfs_read+0xc5/0x180 > >> [ 148.796672] ksys_read+0x68/0xe0 > >> [ 148.796688] do_syscall_64+0x5c/0xa0 > >> [ 148.796704] entry_SYSCALL_64_after_hwframe+0x49/0xbe > >> [ 148.796721] RIP: 0033:0x7f3ab1646412 > >> > >> ...on a non-debug kernel it just crashes. > >> > >> In this case lsmem is failing when reading memory96: > >> > >> openat(3, "memory96/removable", O_RDONLY|O_CLOEXEC) = 4 > >> fcntl(4, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) > >> fstat(4, {st_mode=S_IFREG|0444, st_size=4096, ...}) = 0 > >> read(4, ) = ? > >> +++ killed by SIGSEGV +++ > >> Segmentation fault (core dumped) > >> > >> ...which is phys_index 0x60 => memory address 0x3000000000 > >> > >> On this platform that lands us here: > >> > >> 100000000-303fffffff : System RAM > >> 291f000000-291fe00f70 : Kernel code > >> 2920000000-292051efff : Kernel rodata > >> 2920600000-292093b0bf : Kernel data > >> 29214f3000-2922dfffff : Kernel bss > >> 3040000000-305fffffff : Reserved > >> 3060000000-1aa5fffffff : Persistent Memory > > > > OK, 2GB memblocks and that would mean [0x3000000000, 0x3080000000] > > > >> ...where the last memory block of System RAM is shared with persistent > >> memory. I.e. the block is only partially online which means that > >> page_to_nid() in is_mem_section_removable() will assert or crash for > >> some of the offline pages in that block. > > > > Yes, this patch is a simple workaround. Normal memory hotplug will not > > blow up because it should be able to find out that test_pages_in_a_zone > > is false. Who knows how other potential pfn walkers handle that. > > All other pfn walkers now correctly use pfn_to_online_page() - which > will also result in false positives in this scenario and is still to be > fixed by Dan IIRC. [1] Sorry, it's been too long and this fell out of my cache. I also turned away once the major fire in KVM was put out with special consideration for for devmem pages. What's left these days? ...besides removable_show()?