From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk1-f199.google.com (mail-qk1-f199.google.com [209.85.222.199]) by kanga.kvack.org (Postfix) with ESMTP id C1EA36B22E4 for ; Tue, 20 Nov 2018 20:04:54 -0500 (EST) Received: by mail-qk1-f199.google.com with SMTP id g22so5246729qke.15 for ; Tue, 20 Nov 2018 17:04:54 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id c18si1399447qvb.181.2018.11.20.17.04.53 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 20 Nov 2018 17:04:54 -0800 (PST) Date: Tue, 20 Nov 2018 20:04:51 -0500 (EST) From: Pankaj Gupta Message-ID: <1155749039.35435813.1542762291980.JavaMail.zimbra@redhat.com> In-Reply-To: <1380154502.35259416.1542706636322.JavaMail.zimbra@redhat.com> References: <20181119101616.8901-1-david@redhat.com> <20181119101616.8901-6-david@redhat.com> <1747228.35250472.1542703532881.JavaMail.zimbra@redhat.com> <6258a58b-28c7-c055-0752-e8bd085b835f@redhat.com> <1380154502.35259416.1542706636322.JavaMail.zimbra@redhat.com> Subject: Re: [PATCH v1 5/8] hv_balloon: mark inflated pages PG_offline MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: David Hildenbrand Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, devel@linuxdriverproject.org, linux-fsdevel@vger.kernel.org, linux-pm@vger.kernel.org, xen-devel@lists.xenproject.org, kexec-ml , pv-drivers@vmware.com, "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , Kairui Song , Vitaly Kuznetsov , Andrew Morton , Matthew Wilcox , Michal Hocko , "Michael S. Tsirkin" > > >> --- > > >> drivers/hv/hv_balloon.c | 14 ++++++++++++-- > > >> 1 file changed, 12 insertions(+), 2 deletions(-) > > >> > > >> diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c > > >> index 211f3fe3a038..47719862e57f 100644 > > >> --- a/drivers/hv/hv_balloon.c > > >> +++ b/drivers/hv/hv_balloon.c > > >> @@ -681,8 +681,13 @@ static struct notifier_block hv_memory_nb = { > > >> /* Check if the particular page is backed and can be onlined and online > > >> it. > > >> */ > > >> static void hv_page_online_one(struct hv_hotadd_state *has, struct page > > >> *pg) > > >> { > > >> - if (!has_pfn_is_backed(has, page_to_pfn(pg))) > > >> + if (!has_pfn_is_backed(has, page_to_pfn(pg))) { > > >> + if (!PageOffline(pg)) > > >> + __SetPageOffline(pg); > > >> return; > > >> + } > > >> + if (PageOffline(pg)) > > >> + __ClearPageOffline(pg); > > >> > > >> /* This frame is currently backed; online the page. */ > > >> __online_page_set_limits(pg); > > >> @@ -1201,6 +1206,7 @@ static void free_balloon_pages(struct > > >> hv_dynmem_device > > >> *dm, > > >> > > >> for (i = 0; i < num_pages; i++) { > > >> pg = pfn_to_page(i + start_frame); > > >> + __ClearPageOffline(pg); > > > > > > Just thinking, do we need to care for clearing PageOffline flag before > > > freeing > > > a balloon'd page? > > > > Yes we have to otherwise the code will crash when trying to set PageBuddy. > > > > (only one page type at a time may be set right now, and it makes sense. > > A page that is offline cannot e.g. be a buddy page) > > o.k > > > > So PageOffline is completely managed by the page owner. > > Makes sense. Thanks for explaining. Looks good to me. Acked-by: Pankaj gupta