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bh=CwPIdL0NWwvEkieq0eu1e0ds0YFIVTFLsbJMqK780Ng=; b=Dq++VEeIcmuFW+cKKklYQBOGhNaysWQSt8cjWX7Oogj4W4BHTP/U+GYYPyFlFuVZ/R8HcT 8iY7NxC+7YPoc0BQ== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id 80EF813479; Tue, 26 Aug 2025 21:52:38 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id N1hwEKYsrmjNTQAAD6G6ig (envelope-from ); Tue, 26 Aug 2025 21:52:38 +0000 From: Fabiano Rosas To: Michael Tokarev Cc: Marco.Cavenati@eurecom.fr, mjt@tls.msk.ru, peterx@redhat.com, qemu-devel@nongnu.org, qemu-trivial@nongnu.org, Akihiko Odaki Subject: Re: [PATCH] migration: fix SEEK_CUR offset calculation in qio_channel_block_seek In-Reply-To: References: <871pudmlmj.fsf@suse.de> Date: Tue, 26 Aug 2025 18:52:35 -0300 Message-ID: <87plchkaxo.fsf@suse.de> MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Queue-Id: 11D0721266 X-Rspamd-Action: no action X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Spamd-Result: default: False [-4.50 / 50.00]; BAYES_HAM(-2.99)[99.97%]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; RCVD_VIA_SMTP_AUTH(0.00)[]; MISSING_XM_UA(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; RCPT_COUNT_SEVEN(0.00)[7]; RCVD_TLS_ALL(0.00)[]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_TRACE(0.00)[suse.de:+] Received-SPF: pass client-ip=2a07:de40:b251:101:10:150:64:1; envelope-from=farosas@suse.de; helo=smtp-out1.suse.de X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-trivial@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-trivial-bounces+qemu-trivial=archiver.kernel.org@nongnu.org Sender: qemu-trivial-bounces+qemu-trivial=archiver.kernel.org@nongnu.org Michael Tokarev writes: +CC Akihiko > Hi! > > This is > > commit c0b32426ce56182c1ce2a12904f3a702c2ecc460 > Author: Marco Cavenati > Date: Wed Mar 26 17:22:30 2025 +0100 > > migration: fix SEEK_CUR offset calculation in qio_channel_block_seek > > which went to 10.0.0-rc2, and has been cherry-picked to > 7.2 and 9.2 stable series. > > Reportedly it breaks migration in 7.2.18 and up. Which is > kinda strange, as it shouldn't do any harm? > Yeah, this is not it. Unless you're using colo or mapped-ram. > https://bugs.debian.org/1112044 > > any guess what's going on? > The virtio changes are probably the issue. One of them touches mhdr.num_buffers, under mergeable_rx_bufs, which is migrated state. The flag in turn depends on VIRTIO_NET_F_MRG_RXBUF, which is set on the cmdline with -device virtio-net-pci,mrg_rxbuf= but also reset by virtio_set_features_nocheck, if I'm reading this right. Let's ask Akihiko. > Thanks, > > /mjt