From patchwork Mon Mar 2 13:49:38 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 11415629 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D076E1395 for ; Mon, 2 Mar 2020 13:53:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B06BF21739 for ; Mon, 2 Mar 2020 13:53:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="R5AnUEKz" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727363AbgCBNxG (ORCPT ); Mon, 2 Mar 2020 08:53:06 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:33976 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726740AbgCBNxF (ORCPT ); Mon, 2 Mar 2020 08:53:05 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1583157184; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=R9YlCAxZTLeLO624BWfRaiPaRVXS4Jlz4OonzSFN6/Y=; b=R5AnUEKz0v4e/TO7XHBzyO/cBVUxFpv/LrxmS/odpRCWFU+O/Tm0BqRdN/SVlZn0m9Zp0o muLc0QJm2s0GBkpYe6qZhOb4Z3rZ1gFgGh81L/S8QTyXLw3UgAfLiUZpmnffFqB0ogefJO hFdKodGy4J1afT4hxKrnHvXI8EI7nnc= 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-40-QkfpYAOAPTGAmQMiM64pbg-1; Mon, 02 Mar 2020 08:53:00 -0500 X-MC-Unique: QkfpYAOAPTGAmQMiM64pbg-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 4E674802563; Mon, 2 Mar 2020 13:52:58 +0000 (UTC) Received: from t480s.redhat.com (ovpn-116-114.ams2.redhat.com [10.36.116.114]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7D9EC397; Mon, 2 Mar 2020 13:52:46 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, virtio-dev@lists.oasis-open.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, Michal Hocko , Andrew Morton , "Michael S . Tsirkin" , David Hildenbrand , Oscar Salvador , Michal Hocko , Pavel Tatashin , Wei Yang , Dan Williams , Qian Cai Subject: [PATCH v1 08/11] mm/memory_hotplug: Introduce offline_and_remove_memory() Date: Mon, 2 Mar 2020 14:49:38 +0100 Message-Id: <20200302134941.315212-9-david@redhat.com> In-Reply-To: <20200302134941.315212-1-david@redhat.com> References: <20200302134941.315212-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org virtio-mem wants to offline and remove a memory block once it unplugged all subblocks (e.g., using alloc_contig_range()). Let's provide an interface to do that from a driver. virtio-mem already supports to offline partially unplugged memory blocks. Offlining a fully unplugged memory block will not require to migrate any pages. All unplugged subblocks are PageOffline() and have a reference count of 0 - so offlining code will simply skip them. All we need is an interface to offline and remove the memory from kernel module context, where we don't have access to the memory block devices (esp. find_memory_block() and device_offline()) and the device hotplug lock. To keep things simple, allow to only work on a single memory block. Cc: Andrew Morton Cc: David Hildenbrand Cc: Oscar Salvador Cc: Michal Hocko Cc: Pavel Tatashin Cc: Wei Yang Cc: Dan Williams Cc: Qian Cai Signed-off-by: David Hildenbrand Acked-by: Michal Hocko --- include/linux/memory_hotplug.h | 1 + mm/memory_hotplug.c | 37 ++++++++++++++++++++++++++++++++++ 2 files changed, 38 insertions(+) diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h index f4d59155f3d4..a98aa16dbfa1 100644 --- a/include/linux/memory_hotplug.h +++ b/include/linux/memory_hotplug.h @@ -311,6 +311,7 @@ extern void try_offline_node(int nid); extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages); extern int remove_memory(int nid, u64 start, u64 size); extern void __remove_memory(int nid, u64 start, u64 size); +extern int offline_and_remove_memory(int nid, u64 start, u64 size); #else static inline bool is_mem_section_removable(unsigned long pfn, diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index ab1c31e67fd1..d0d337918a15 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1818,4 +1818,41 @@ int remove_memory(int nid, u64 start, u64 size) return rc; } EXPORT_SYMBOL_GPL(remove_memory); + +/* + * Try to offline and remove a memory block. Might take a long time to + * finish in case memory is still in use. Primarily useful for memory devices + * that logically unplugged all memory (so it's no longer in use) and want to + * offline + remove the memory block. + */ +int offline_and_remove_memory(int nid, u64 start, u64 size) +{ + struct memory_block *mem; + int rc = -EINVAL; + + if (!IS_ALIGNED(start, memory_block_size_bytes()) || + size != memory_block_size_bytes()) + return rc; + + lock_device_hotplug(); + mem = find_memory_block(__pfn_to_section(PFN_DOWN(start))); + if (mem) + rc = device_offline(&mem->dev); + /* Ignore if the device is already offline. */ + if (rc > 0) + rc = 0; + + /* + * In case we succeeded to offline the memory block, remove it. + * This cannot fail as it cannot get onlined in the meantime. + */ + if (!rc) { + rc = try_remove_memory(nid, start, size); + WARN_ON_ONCE(rc); + } + unlock_device_hotplug(); + + return rc; +} +EXPORT_SYMBOL_GPL(offline_and_remove_memory); #endif /* CONFIG_MEMORY_HOTREMOVE */