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=-9.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY autolearn=ham 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 0CDA0C433DF for ; Thu, 15 Oct 2020 08:28:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 86B5522249 for ; Thu, 15 Oct 2020 08:28:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728749AbgJOI2N (ORCPT ); Thu, 15 Oct 2020 04:28:13 -0400 Received: from out30-131.freemail.mail.aliyun.com ([115.124.30.131]:51795 "EHLO out30-131.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725959AbgJOI2L (ORCPT ); Thu, 15 Oct 2020 04:28:11 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R961e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04423;MF=richard.weiyang@linux.alibaba.com;NM=1;PH=DS;RN=8;SR=0;TI=SMTPD_---0UC5QMf8_1602750488; Received: from localhost(mailfrom:richard.weiyang@linux.alibaba.com fp:SMTPD_---0UC5QMf8_1602750488) by smtp.aliyun-inc.com(127.0.0.1); Thu, 15 Oct 2020 16:28:08 +0800 Date: Thu, 15 Oct 2020 16:28:08 +0800 From: Wei Yang To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, virtualization@lists.linux-foundation.org, Andrew Morton , "Michael S . Tsirkin" , Jason Wang , Pankaj Gupta Subject: Re: [PATCH v1 05/29] virtio-mem: generalize check for added memory Message-ID: <20201015082808.GE86495@L-31X9LVDL-1304.local> Reply-To: Wei Yang References: <20201012125323.17509-1-david@redhat.com> <20201012125323.17509-6-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201012125323.17509-6-david@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 12, 2020 at 02:52:59PM +0200, David Hildenbrand wrote: >Let's check by traversing busy system RAM resources instead, to avoid >relying on memory block states. > >Don't use walk_system_ram_range(), as that works on pages and we want to >use the bare addresses we have easily at hand. > >Cc: "Michael S. Tsirkin" >Cc: Jason Wang >Cc: Pankaj Gupta >Signed-off-by: David Hildenbrand >--- > drivers/virtio/virtio_mem.c | 19 +++++++++++++++---- > 1 file changed, 15 insertions(+), 4 deletions(-) > >diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c >index b3eebac7191f..6bbd1cfd10d3 100644 >--- a/drivers/virtio/virtio_mem.c >+++ b/drivers/virtio/virtio_mem.c >@@ -1749,6 +1749,20 @@ static void virtio_mem_delete_resource(struct virtio_mem *vm) > vm->parent_resource = NULL; > } > >+static int virtio_mem_range_has_system_ram(struct resource *res, void *arg) >+{ >+ return 1; >+} >+ >+static bool virtio_mem_has_memory_added(struct virtio_mem *vm) >+{ >+ const unsigned long flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY; >+ >+ return walk_iomem_res_desc(IORES_DESC_NONE, flags, vm->addr, >+ vm->addr + vm->region_size, NULL, >+ virtio_mem_range_has_system_ram) == 1; >+} >+ > static int virtio_mem_probe(struct virtio_device *vdev) > { > struct virtio_mem *vm; >@@ -1870,10 +1884,7 @@ static void virtio_mem_remove(struct virtio_device *vdev) > * the system. And there is no way to stop the driver/device from going > * away. Warn at least. > */ >- if (vm->nb_mb_state[VIRTIO_MEM_MB_STATE_OFFLINE] || >- vm->nb_mb_state[VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL] || >- vm->nb_mb_state[VIRTIO_MEM_MB_STATE_ONLINE] || >- vm->nb_mb_state[VIRTIO_MEM_MB_STATE_ONLINE_PARTIAL]) { >+ if (virtio_mem_has_memory_added(vm)) { I am not sure this would be more efficient. > dev_warn(&vdev->dev, "device still has system memory added\n"); > } else { > virtio_mem_delete_resource(vm); BTW, I got one question during review. Per my understanding, there are 4 states of a virtio memory block * OFFLINE[_PARTIAL] * ONLINE[_PARTIAL] While, if my understanding is correct, those two offline states are transient. If the required range is onlined, the state would be change to ONLINE[_PARTIAL] respectively. If it is not, the state is reverted to UNUSED or PLUGGED. What I am lost is why you do virtio_mem_mb_remove() on OFFLINE_PARTIAL memory block? Since we wait for the workqueue finish its job. Also, during virtio_mem_remove(), we just handle OFFLINE_PARTIAL memory block. How about memory block in other states? It is not necessary to remove ONLINE[_PARTIAL] memroy blocks? Thanks in advance, since I may missed some concepts. >-- >2.26.2 -- Wei Yang Help you, Help me