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David Alan Gilbert" , Prasad Pandit , Paolo Bonzini , Yury Kotov , Juraj Marcin Subject: Re: [PATCH 08/13] migration: Thread-ify precopy vmstate load process Message-ID: References: <20251022192612.2737648-9-peterx@redhat.com> <87y0m7df46.fsf@suse.de> <871pju1wlv.fsf@suse.de> <87fr89psu5.fsf@suse.de> <87jyxhmdp6.fsf@suse.de> <87cy34ktd0.fsf@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <87cy34ktd0.fsf@suse.de> Received-SPF: pass client-ip=170.10.129.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.087, 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_H2=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-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: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Tue, Jan 20, 2026 at 03:54:19PM -0300, Fabiano Rosas wrote: > Peter Xu writes: > > > On Fri, Jan 16, 2026 at 06:48:21PM -0300, Fabiano Rosas wrote: > >> Another one for the pile: > >> > >> #5 0x00007f0beda4fb32 in __assert_fail (assertion=0x55b8c3ed8cb8 "mode >= 0 ...) at assert.c:103 > >> #6 0x000055b8c3a1d7a9 in migrate_mode () at ../migration/options.c:882 > >> #7 0x000055b8c3a1084e in fill_source_migration_info (info=0x55b8f1291650) at ../migration/migration.c:1322 > >> #8 0x000055b8c3a10cae in qmp_query_migrate (errp=0x7fff5742ae80) at ../migration/migration.c:1438 > >> #9 0x000055b8c3d4bc2a in qmp_marshal_query_migrate (args=0x55b8f11f2280, ret=0x7f0becd25da8, errp=0x7f0becd25da0) at qapi/qapi-commands-migration.c:48 > >> #10 0x000055b8c3d9a13b in do_qmp_dispatch_bh (opaque=0x7f0becd25e40) at ../qapi/qmp-dispatch.c:128 > >> #11 0x000055b8c3dc6366 in aio_bh_call (bh=0x55b8f12922d0) at ../util/async.c:173 > >> #12 0x000055b8c3dc6482 in aio_bh_poll (ctx=0x55b8f10741e0) at ../util/async.c:220 > >> #13 0x000055b8c3da9832 in aio_poll (ctx=0x55b8f10741e0, blocking=false) at ../util/aio-posix.c:719 > >> #14 0x000055b8c3cea017 in monitor_cleanup () at ../monitor/monitor.c:676 > >> #15 0x000055b8c39ef646 in qemu_cleanup (status=0) at ../system/runstate.c:999 > >> #16 0x000055b8c3cec38e in qemu_default_main (opaque=0x0) at ../system/main.c:51 > >> #17 0x000055b8c3cec430 in main (argc=33, argv=0x7fff5742b208) at > >> #../system/main.c:93 > >> > >> (gdb) p/x mode > >> $8 = 0xcccccccc > > > > What's the reproducer? Is it easy to reproduce? > > > > Just hammering some make check instances in parallel, as usual. > > > I wonder if current_migration released already, or if monitor should still > > process any QMP handler if the VM is shutting down.. > > > > monitor_cleanup says it will continue dispatching and just never send a > response to the command. It seems migration will need it's own way of > tracking this. > > Maybe as a first step we could clear current_migration at > migration_instance_finalize(). > (I see device-introspect-test doesn't like it. I'll look into it) > > > Is this only happening after this series applied? I can't yet see how the > > threadify affected it.. > > No, sorry, I posted here because I think this affects this series' > assumptions about the BQL. Aha, you reminded me on this work, remember to check it out (I forgot most of it.. as usual..): https://lore.kernel.org/qemu-devel/20241029211607.2114845-8-peterx@redhat.com I also recall besides the singleton idea, we can also take a mutex and release current_migration at finalize(), then fetch current_migration will instead need to take a refcount and also with mutex held. Anyway, thanks for looking into it. Now, it's all yours. :) -- Peter Xu