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=-8.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 4513EC10F27 for ; Mon, 9 Mar 2020 13:18:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1E65B22525 for ; Mon, 9 Mar 2020 13:18:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="hmfQfJvs" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726497AbgCINSe (ORCPT ); Mon, 9 Mar 2020 09:18:34 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:22260 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725956AbgCINSe (ORCPT ); Mon, 9 Mar 2020 09:18:34 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1583759912; 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: in-reply-to:in-reply-to:references:references; bh=1K5R56oPivAmrjTNpcDkpowCNoJPz3om5lUYieNs7Bw=; b=hmfQfJvs2kq+xY3ZzfGOA4w8iCBI+88wwb7I0jLGJ05kGmd1XbBW9umub/+KAN/SrEUh4e zm5sEZeaVxWxbKzKFV71PCjyN4DQIj/La7rZCOtyl255FfDXtg0o5OI4PN0QmYAQZxk8RP apaHEd1+fPEilykI4+sJLmOgQ7uscWw= 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-197-Qr1mgu6CMmm_3by9S08W0Q-1; Mon, 09 Mar 2020 09:18:29 -0400 X-MC-Unique: Qr1mgu6CMmm_3by9S08W0Q-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 2C4F08010D9; Mon, 9 Mar 2020 13:18:26 +0000 (UTC) Received: from localhost (ovpn-12-179.pek2.redhat.com [10.72.12.179]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B8BB48882D; Mon, 9 Mar 2020 13:18:16 +0000 (UTC) Date: Mon, 9 Mar 2020 21:18:12 +0800 From: Baoquan He To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, mhocko@suse.com, richardw.yang@linux.intel.com, dan.j.williams@intel.com, osalvador@suse.de, rppt@linux.ibm.com Subject: Re: [PATCH v3 1/7] mm/hotplug: fix hot remove failure in SPARSEMEM|!VMEMMAP case Message-ID: <20200309131812.GN4937@MiWiFi-R3L-srv> References: <20200307084229.28251-1-bhe@redhat.com> <20200307084229.28251-2-bhe@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/09/20 at 09:58am, David Hildenbrand wrote: > On 07.03.20 09:42, Baoquan He wrote: > > In section_deactivate(), pfn_to_page() doesn't work any more after > > ms->section_mem_map is resetting to NULL in SPARSEMEM|!VMEMMAP case. > > It caused hot remove failure: > > > > kernel BUG at mm/page_alloc.c:4806! > > invalid opcode: 0000 [#1] SMP PTI > > CPU: 3 PID: 8 Comm: kworker/u16:0 Tainted: G W 5.5.0-next-20200205+ #340 > > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015 > > Workqueue: kacpi_hotplug acpi_hotplug_work_fn > > RIP: 0010:free_pages+0x85/0xa0 > > Call Trace: > > __remove_pages+0x99/0xc0 > > arch_remove_memory+0x23/0x4d > > try_remove_memory+0xc8/0x130 > > ? walk_memory_blocks+0x72/0xa0 > > __remove_memory+0xa/0x11 > > acpi_memory_device_remove+0x72/0x100 > > acpi_bus_trim+0x55/0x90 > > acpi_device_hotplug+0x2eb/0x3d0 > > acpi_hotplug_work_fn+0x1a/0x30 > > process_one_work+0x1a7/0x370 > > worker_thread+0x30/0x380 > > ? flush_rcu_work+0x30/0x30 > > kthread+0x112/0x130 > > ? kthread_create_on_node+0x60/0x60 > > ret_from_fork+0x35/0x40 > > > > Let's move the ->section_mem_map resetting after depopulate_section_memmap() > > to fix it. > > > > Fixes: ba72b4c8cf60 ("mm/sparsemem: support sub-section hotplug") > > Signed-off-by: Baoquan He > > Cc: stable@vger.kernel.org > > --- > > mm/sparse.c | 8 ++++++-- > > 1 file changed, 6 insertions(+), 2 deletions(-) > > > > diff --git a/mm/sparse.c b/mm/sparse.c > > index 42c18a38ffaa..1b50c15677d7 100644 > > --- a/mm/sparse.c > > +++ b/mm/sparse.c > > @@ -734,6 +734,7 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages, > > struct mem_section *ms = __pfn_to_section(pfn); > > bool section_is_early = early_section(ms); > > struct page *memmap = NULL; > > + bool empty = false; > > Oh, one NIT: no need to initialize empty to false. Thanks for careful reviewing, David. Not very sure about this, do you have a doc or discussion thread about not initializing local variable? Maybe Andrew can help update it if this is not suggested.