Re: [PATCH 08/13] migration: Thread-ify precopy vmstate load process

[Fabiano Rosas <farosas@suse.de>]

Peter Xu <peterx@redhat.com> 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.