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=-9.7 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=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 1BC2AC433DF for ; Fri, 16 Oct 2020 07:15:18 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1AAA520720 for ; Fri, 16 Oct 2020 07:15:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1AAA520720 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 1B361900003; Fri, 16 Oct 2020 03:15:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1645D900002; Fri, 16 Oct 2020 03:15:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0A215900003; Fri, 16 Oct 2020 03:15:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0009.hostedemail.com [216.40.44.9]) by kanga.kvack.org (Postfix) with ESMTP id D0879900002 for ; Fri, 16 Oct 2020 03:15:15 -0400 (EDT) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 55EC9362D for ; Fri, 16 Oct 2020 07:15:15 +0000 (UTC) X-FDA: 77376927390.04.kiss79_5d0287d2721b Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin04.hostedemail.com (Postfix) with ESMTP id 35A7A800B288 for ; Fri, 16 Oct 2020 07:15:15 +0000 (UTC) X-HE-Tag: kiss79_5d0287d2721b X-Filterd-Recvd-Size: 6698 Received: from out30-132.freemail.mail.aliyun.com (out30-132.freemail.mail.aliyun.com [115.124.30.132]) by imf10.hostedemail.com (Postfix) with ESMTP for ; Fri, 16 Oct 2020 07:15:13 +0000 (UTC) X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R171e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04426;MF=richard.weiyang@linux.alibaba.com;NM=1;PH=DS;RN=8;SR=0;TI=SMTPD_---0UCAePNM_1602832502; Received: from localhost(mailfrom:richard.weiyang@linux.alibaba.com fp:SMTPD_---0UCAePNM_1602832502) by smtp.aliyun-inc.com(127.0.0.1); Fri, 16 Oct 2020 15:15:03 +0800 Date: Fri, 16 Oct 2020 15:15:02 +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 13/29] virtio-mem: factor out handling of fake-offline pages in memory notifier Message-ID: <20201016071502.GM86495@L-31X9LVDL-1304.local> Reply-To: Wei Yang References: <20201012125323.17509-1-david@redhat.com> <20201012125323.17509-14-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201012125323.17509-14-david@redhat.com> 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 Mon, Oct 12, 2020 at 02:53:07PM +0200, David Hildenbrand wrote: >Let's factor out the core pieces and place the implementation next to >virtio_mem_fake_offline(). We'll reuse this functionality soon. > >Cc: "Michael S. Tsirkin" >Cc: Jason Wang >Cc: Pankaj Gupta >Signed-off-by: David Hildenbrand >--- > drivers/virtio/virtio_mem.c | 73 +++++++++++++++++++++++++------------ > 1 file changed, 50 insertions(+), 23 deletions(-) > >diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c >index d132bc54ef57..a2124892e510 100644 >--- a/drivers/virtio/virtio_mem.c >+++ b/drivers/virtio/virtio_mem.c >@@ -168,6 +168,10 @@ static LIST_HEAD(virtio_mem_devices); > > static void virtio_mem_online_page_cb(struct page *page, unsigned int order); > static void virtio_mem_retry(struct virtio_mem *vm); >+static void virtio_mem_fake_offline_going_offline(unsigned long pfn, >+ unsigned long nr_pages); >+static void virtio_mem_fake_offline_cancel_offline(unsigned long pfn, >+ unsigned long nr_pages); > > /* > * Register a virtio-mem device so it will be considered for the online_page >@@ -604,27 +608,15 @@ static void virtio_mem_notify_going_offline(struct virtio_mem *vm, > unsigned long mb_id) > { > const unsigned long nr_pages = PFN_DOWN(vm->subblock_size); >- struct page *page; > unsigned long pfn; >- int sb_id, i; >+ int sb_id; > > for (sb_id = 0; sb_id < vm->nb_sb_per_mb; sb_id++) { > if (virtio_mem_mb_test_sb_plugged(vm, mb_id, sb_id, 1)) > continue; >- /* >- * Drop our reference to the pages so the memory can get >- * offlined and add the unplugged pages to the managed >- * page counters (so offlining code can correctly subtract >- * them again). >- */ > pfn = PFN_DOWN(virtio_mem_mb_id_to_phys(mb_id) + > sb_id * vm->subblock_size); >- adjust_managed_page_count(pfn_to_page(pfn), nr_pages); One question about the original code, why we want to adjust count here? The code flow is __offline_pages() memory_notify(MEM_GOING_OFFLINE, &arg) virtio_mem_notify_going_offline(vm, mb_id) adjust_managed_page_count(pfn_to_page(pfn), nr_pages) adjust_managed_page_count(pfn_to_page(start_pfn), -offlined_pages) Do we adjust the count twice? >- for (i = 0; i < nr_pages; i++) { >- page = pfn_to_page(pfn + i); >- if (WARN_ON(!page_ref_dec_and_test(page))) >- dump_page(page, "unplugged page referenced"); >- } >+ virtio_mem_fake_offline_going_offline(pfn, nr_pages); > } > } > >@@ -633,21 +625,14 @@ static void virtio_mem_notify_cancel_offline(struct virtio_mem *vm, > { > const unsigned long nr_pages = PFN_DOWN(vm->subblock_size); > unsigned long pfn; >- int sb_id, i; >+ int sb_id; > > for (sb_id = 0; sb_id < vm->nb_sb_per_mb; sb_id++) { > if (virtio_mem_mb_test_sb_plugged(vm, mb_id, sb_id, 1)) > continue; >- /* >- * Get the reference we dropped when going offline and >- * subtract the unplugged pages from the managed page >- * counters. >- */ > pfn = PFN_DOWN(virtio_mem_mb_id_to_phys(mb_id) + > sb_id * vm->subblock_size); >- adjust_managed_page_count(pfn_to_page(pfn), -nr_pages); >- for (i = 0; i < nr_pages; i++) >- page_ref_inc(pfn_to_page(pfn + i)); >+ virtio_mem_fake_offline_cancel_offline(pfn, nr_pages); > } > } > >@@ -853,6 +838,48 @@ static int virtio_mem_fake_offline(unsigned long pfn, unsigned long nr_pages) > return 0; > } > >+/* >+ * Handle fake-offline pages when memory is going offline - such that the >+ * pages can be skipped by mm-core when offlining. >+ */ >+static void virtio_mem_fake_offline_going_offline(unsigned long pfn, >+ unsigned long nr_pages) >+{ >+ struct page *page; >+ unsigned long i; >+ >+ /* >+ * Drop our reference to the pages so the memory can get offlined >+ * and add the unplugged pages to the managed page counters (so >+ * offlining code can correctly subtract them again). >+ */ >+ adjust_managed_page_count(pfn_to_page(pfn), nr_pages); >+ /* Drop our reference to the pages so the memory can get offlined. */ >+ for (i = 0; i < nr_pages; i++) { >+ page = pfn_to_page(pfn + i); >+ if (WARN_ON(!page_ref_dec_and_test(page))) >+ dump_page(page, "fake-offline page referenced"); >+ } >+} >+ >+/* >+ * Handle fake-offline pages when memory offlining is canceled - to undo >+ * what we did in virtio_mem_fake_offline_going_offline(). >+ */ >+static void virtio_mem_fake_offline_cancel_offline(unsigned long pfn, >+ unsigned long nr_pages) >+{ >+ unsigned long i; >+ >+ /* >+ * Get the reference we dropped when going offline and subtract the >+ * unplugged pages from the managed page counters. >+ */ >+ adjust_managed_page_count(pfn_to_page(pfn), -nr_pages); >+ for (i = 0; i < nr_pages; i++) >+ page_ref_inc(pfn_to_page(pfn + i)); >+} >+ > static void virtio_mem_online_page_cb(struct page *page, unsigned int order) > { > const unsigned long addr = page_to_phys(page); >-- >2.26.2 -- Wei Yang Help you, Help me