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Tue, 28 Jul 2020 11:45:02 +0000 (UTC) Subject: Re: migration: broken snapshot saves appear on s390 when small fields in migration stream removed To: Paolo Bonzini , Vladimir Sementsov-Ogievskiy , Bruce Rogers , Claudio Fontana , Thomas Huth , Juan Quintela , "Dr. David Alan Gilbert" , Kevin Wolf References: <8bbafdec-836d-b7de-cab8-7a325b6e238d@suse.de> <55c406cd-b9ca-4e9b-0acd-d33cfe2a70e3@redhat.com> <8125b1ff-373a-aadc-eccf-27c567007a27@redhat.com> <8ff7eeab-bef1-0957-a95c-72819680c431@suse.de> <1db6d502-73d1-5e3d-10d1-796d80ab8f07@suse.de> <13728e69-75a5-2edc-9ed3-6e08d94c722d@suse.de> <636bb3c4-2242-284b-30cd-299f447117c2@suse.de> <5f455e82e0a4f3662918dcdc85d1cfc5a3187896.camel@suse.com> <72ff33d4-653f-5702-fc04-9090653ab782@redhat.com> From: Max Reitz Autocrypt: addr=mreitz@redhat.com; prefer-encrypt=mutual; keydata= mQENBFXOJlcBCADEyyhOTsoa/2ujoTRAJj4MKA21dkxxELVj3cuILpLTmtachWj7QW+TVG8U /PsMCFbpwsQR7oEy8eHHZwuGQsNpEtNC2G/L8Yka0BIBzv7dEgrPzIu+W3anZXQW4702+uES U29G8TP/NGfXRRHGlbBIH9KNUnOSUD2vRtpOLXkWsV5CN6vQFYgQfFvmp5ZpPeUe6xNplu8V mcTw8OSEDW/ZnxJc8TekCKZSpdzYoxfzjm7xGmZqB18VFwgJZlIibt1HE0EB4w5GsD7x5ekh awIe3RwoZgZDLQMdOitJ1tUc8aqaxvgA4tz6J6st8D8pS//m1gAoYJWGwwIVj1DjTYLtABEB AAG0HU1heCBSZWl0eiA8bXJlaXR6QHJlZGhhdC5jb20+iQFTBBMBCAA9AhsDBQkSzAMABQsJ CAcCBhUICQoLAgQWAgMBAh4BAheABQJVzie5FRhoa3A6Ly9rZXlzLmdudXBnLm5ldAAKCRD0 B9sAYdXPQDcIB/9uNkbYEex1rHKz3mr12uxYMwLOOFY9fstP5aoVJQ1nWQVB6m2cfKGdcRe1 2/nFaHSNAzT0NnKz2MjhZVmcrpyd2Gp2QyISCfb1FbT82GMtXFj1wiHmPb3CixYmWGQUUh+I AvUqsevLA+WihgBUyaJq/vuDVM1/K9Un+w+Tz5vpeMidlIsTYhcsMhn0L9wlCjoucljvbDy/ 8C9L2DUdgi3XTa0ORKeflUhdL4gucWoAMrKX2nmPjBMKLgU7WLBc8AtV+84b9OWFML6NEyo4 4cP7cM/07VlJK53pqNg5cHtnWwjHcbpGkQvx6RUx6F1My3y52vM24rNUA3+ligVEgPYBuQEN BFXOJlcBCADAmcVUNTWT6yLWQHvxZ0o47KCP8OcLqD+67T0RCe6d0LP8GsWtrJdeDIQk+T+F xO7DolQPS6iQ6Ak2/lJaPX8L0BkEAiMuLCKFU6Bn3lFOkrQeKp3u05wCSV1iKnhg0UPji9V2 W5eNfy8F4ZQHpeGUGy+liGXlxqkeRVhLyevUqfU0WgNqAJpfhHSGpBgihUupmyUg7lfUPeRM DzAN1pIqoFuxnN+BRHdAecpsLcbR8sQddXmDg9BpSKozO/JyBmaS1RlquI8HERQoe6EynJhd 64aICHDfj61rp+/0jTIcevxIIAzW70IadoS/y3DVIkuhncgDBvGbF3aBtjrJVP+5ABEBAAGJ ASUEGAEIAA8FAlXOJlcCGwwFCRLMAwAACgkQ9AfbAGHVz0CbFwf9F/PXxQR9i4N0iipISYjU sxVdjJOM2TMut+ZZcQ6NSMvhZ0ogQxJ+iEQ5OjnIputKvPVd5U7WRh+4lF1lB/NQGrGZQ1ic alkj6ocscQyFwfib+xIe9w8TG1CVGkII7+TbS5pXHRxZH1niaRpoi/hYtgzkuOPp35jJyqT/ /ELbqQTDAWcqtJhzxKLE/ugcOMK520dJDeb6x2xVES+S5LXby0D4juZlvUj+1fwZu+7Io5+B bkhSVPb/QdOVTpnz7zWNyNw+OONo1aBUKkhq2UIByYXgORPFnbfMY7QWHcjpBVw9MgC4tGeF R4bv+1nAMMxKmb5VvQCExr0eFhJUAHAhVg== Message-ID: <0e175bbb-6d5e-f509-7a4f-e3e4769c13a1@redhat.com> Date: Tue, 28 Jul 2020 13:45:01 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mreitz@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="fJmBSE1mD7sHU4ZueqTl5fgl8GNpCJfog" Received-SPF: pass client-ip=207.211.31.81; envelope-from=mreitz@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/28 00:06:48 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Jason J. Herne" , Fam Zheng , Liang Yan , Peter Maydell , Cornelia Huck , qemu-devel , Stefan Hajnoczi Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --fJmBSE1mD7sHU4ZueqTl5fgl8GNpCJfog Content-Type: multipart/mixed; boundary="Fap77OmQdllUuxB9YJpseqEiBe5MuvYY6" --Fap77OmQdllUuxB9YJpseqEiBe5MuvYY6 Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 28.07.20 13:35, Paolo Bonzini wrote: > On 28/07/20 13:33, Vladimir Sementsov-Ogievskiy wrote: >>> Thanks for both your investigation.=C2=A0 Does the attached patch help? >> >> For me, the reproducer is fixed with your patch. >=20 > Is it possible to make a quick testcase using qemu-io? This seems to work: $ qemu-img create -f qcow2 -o cluster_size=3D512 base.qcow2 512 $ qemu-img create -f qcow2 -o cluster_size=3D512 -F qcow2 -b base.qcow2 \ top.qcow2 1024 $ qemu-io -c 'write -P 42 0 512' top.qcow2 $ qemu-io -c 'read -v 0 1024' top.qcow2 That should print 512 times =E2=80=9C2a=E2=80=9D and then 512 times =E2=80= =9C00=E2=80=9D, but beyond 512, the buffer stays uninitialized; instead, the first 512 bytes are zeroed. (With the patch, it works as expected.) --Fap77OmQdllUuxB9YJpseqEiBe5MuvYY6-- --fJmBSE1mD7sHU4ZueqTl5fgl8GNpCJfog Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAl8gD70ACgkQ9AfbAGHV z0BsBwgAvriHLQP+N/Jr6UIBzrTVwV5+GOcvwsnuh+1C++PvtR59+fZQHbqv3EAt LWnnMQcQj/P13hCARAN2jOrNxcKvehuLamf72jsWBdQRBuIVx8GLXhDWYy5kib0k B5vTGpomijX9w257lGpbhO+6ZMoj9USCWtraWIYXnB23wuMqeneZN/S3HhjP7Xct CQT67zzEvV3ZPNTM8eHyxACXM9o7v04Xlq5f+xvr7kEBCEVTyD3eC3hsE0o3NGf1 exwD0MAc8Av+kayn7UuibUANM3cMewgnxyPpbyQHuxAnha4VgS2vD2B4JmBmXLP4 SpDekmgGuCan5jeFD10hvXXW6cTYfQ== =hhYx -----END PGP SIGNATURE----- --fJmBSE1mD7sHU4ZueqTl5fgl8GNpCJfog--