From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail1.bemta37.messagelabs.com (mail1.bemta37.messagelabs.com [85.158.142.112]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0BC7917C9 for ; Fri, 24 Mar 2023 01:51:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fujitsu.com; s=170520fj; t=1679622672; i=@fujitsu.com; bh=YXDfWY42T6qJONVQUy0U7qSy0bQjE512aKax5Mg1h+g=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type:Content-Transfer-Encoding; b=YMGbvUatmXw2F9DWAw+vI/DNEObTeDkrlZ/B5iF7UWOUjmKZOhDwMd9JtgXUHXSjY c9QDCJs6vai5ZYrpMDSu7+T0UitzRLgcD6O1AcpOaFB8HUA/P038KcA9wPhvxCFw0b 3yT6hsOLy66T8gVueejSfOfK8asZcbanugen5DYF6k4dgBwXwF4kBPkkTdJGg8juzk f05cbJNUKAtdOe4DeH2mJvQqEw4imivwdNqgOkeiJV6nM7hi2y6Plkg8WvWG7LtRZn RkZf2qzQmuyDrxA6oAj39YAFMDHO0+9g1m/DsGgTGyAqwVWfXaUQpGX6mgvTfwtewV BIgkRAx0m+Ebw== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprJKsWRWlGSWpSXmKPExsViZ8ORpMvJJJt i0NMuYTFn/Ro2i+lTLzBaXH7CZzF7ejOTxZ69J1ksVv74w2rx+8ccNgd2j80rtDwW73nJ5LFp VSebx4kZv1k8XmyeyehxZsERdo/Pm+QC2KNYM/OS8isSWDPm/t/OWvCZs6Ll6hy2BsZ+ji5GL g4hgY2MEtd+XGSDcJYwSTxbsYgVwtnGKPF/0wOgDCcHr4CdRPfTZywgNouAqsTK1ZNYIeKCEi dnPgGLiwokSxw73wpUz8EhLBAqcXSNI0hYREBXYtXzXcwgM5kFpjNKTGpqYYRY8J1RYsLxlWC D2AR0JC4s+Atmcwp4S1zbdooZxGYWsJBY/OYgO4QtL9G8dTZYXEJASeLi1zusEHaFROP0Q0wQ tprE1XObmCcwCs1Cct8sJKNmIRm1gJF5FaNZcWpRWWqRrqleUlFmekZJbmJmjl5ilW6iXmqpb l5+UUmGrqFeYnmxXmpxsV5xZW5yTopeXmrJJkZgjKUUJzPsYOzs+6t3iFGSg0lJlFciVDpFiC 8pP6UyI7E4I76oNCe1+BCjDAeHkgSv63+ZFCHBotT01Iq0zBxgvMOkJTh4lER45/0DSvMWFyT mFmemQ6ROMSpKifMaMMimCAmAJDJK8+DaYCnmEqOslDAvIwMDgxBPQWpRbmYJqvwrRnEORiVh 3jcg23ky80rgpr8CWswEtNi5BmxxSSJCSqqBScD2l8TrHsllQpN5sgLWbz39MG7Xyua48+oCB +f8loqsurt63beF36ZN6Ixnd0jdf+rHlqVrOMv4p57KSb59pkOOVz02bkrSwecXm0xWWd9b9J lLcs/5mw93FB+oFo/yP/XlWeGNM/373/+3ET9Y7W67rODTxV0ftY5+E02Rje1POlzJ/94sSGW z2P6rbalXm4Ubk/xzphnuO7lwvY3TvLcOUTcDJ6yza7igd2bVZJZrMtIhTN49nOcyLDn3cjRL r9ylqKOQxVagrrZs2Z8wt3k6sZkuP4/86f/t6hgnvOWtlsX2J+oL6u4/OHuscWHKwoda9i7Gy pVMSyvvppkky37e+P/y7vD3U1O8/ZS/OiuxFGckGmoxFxUnAgAF+rL5rAMAAA== X-Env-Sender: ruansy.fnst@fujitsu.com X-Msg-Ref: server-4.tower-745.messagelabs.com!1679622664!650496!1 X-Originating-IP: [62.60.8.98] X-SYMC-ESS-Client-Auth: outbound-route-from=pass X-StarScan-Received: X-StarScan-Version: 9.104.1; banners=-,-,- X-VirusChecked: Checked Received: (qmail 19407 invoked from network); 24 Mar 2023 01:51:05 -0000 Received: from unknown (HELO n03ukasimr03.n03.fujitsu.local) (62.60.8.98) by server-4.tower-745.messagelabs.com with ECDHE-RSA-AES256-GCM-SHA384 encrypted SMTP; 24 Mar 2023 01:51:05 -0000 Received: from n03ukasimr03.n03.fujitsu.local (localhost [127.0.0.1]) by n03ukasimr03.n03.fujitsu.local (Postfix) with ESMTP id BB3E21B0; Fri, 24 Mar 2023 01:51:04 +0000 (GMT) Received: from R01UKEXCASM121.r01.fujitsu.local (R01UKEXCASM121 [10.183.43.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by n03ukasimr03.n03.fujitsu.local (Postfix) with ESMTPS id AFBEF1AF; Fri, 24 Mar 2023 01:51:04 +0000 (GMT) Received: from [192.168.50.5] (10.167.234.230) by R01UKEXCASM121.r01.fujitsu.local (10.183.43.173) with Microsoft SMTP Server (TLS) id 15.0.1497.42; Fri, 24 Mar 2023 01:51:01 +0000 Message-ID: Date: Fri, 24 Mar 2023 09:50:54 +0800 Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.7.1 Subject: Re: [PATCH] fsdax: unshare: zero destination if srcmap is HOLE or UNWRITTEN To: Andrew Morton CC: , , , , , References: <1679483469-2-1-git-send-email-ruansy.fnst@fujitsu.com> <20230322160311.89efea3493db4c4ccad40a25@linux-foundation.org> <20230323151112.1cc3cf57b35f2dc704ff1af8@linux-foundation.org> From: Shiyang Ruan In-Reply-To: <20230323151112.1cc3cf57b35f2dc704ff1af8@linux-foundation.org> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.167.234.230] X-ClientProxiedBy: G08CNEXCHPEKD07.g08.fujitsu.local (10.167.33.80) To R01UKEXCASM121.r01.fujitsu.local (10.183.43.173) X-Virus-Scanned: ClamAV using ClamSMTP 在 2023/3/24 6:11, Andrew Morton 写道: > On Thu, 23 Mar 2023 14:50:38 +0800 Shiyang Ruan wrote: > >> >> >> 在 2023/3/23 7:03, Andrew Morton 写道: >>> On Wed, 22 Mar 2023 11:11:09 +0000 Shiyang Ruan wrote: >>> >>>> unshare copies data from source to destination. But if the source is >>>> HOLE or UNWRITTEN extents, we should zero the destination, otherwise the >>>> result will be unexpectable. >>> >>> Please provide much more detail on the user-visible effects of the bug. >>> For example, are we leaking kernel memory contents to userspace? >> >> This fixes fail of generic/649. > > OK, but this doesn't really help. I'm trying to determine whether this > fix should be backported into -stable kernels and whether it should be > fast-tracked into Linus's current -rc tree. > > But to determine this I (and others) need to know what effect the bug > has upon our users. I didn't get any bug report form users. I just found this by running xfstests. The phenomenon of this problem is: if we funshare a reflinked file which contains HOLE extents, the result of the HOLE extents should be zero but actually not (unexpectable data). The other patch also has no reports from users. -- Thanks, Ruan.