Hi Markus On Mon, Dec 1, 2025 at 10:00 AM Markus Armbruster <[email protected]> wrote: > > Jie Song, Marc-André, is this bug serious enough and the fix safe enough > to still go into 10.2? >
My feeling is that it's a bit late for 10.2, as I suppose this bug has been present for a long time and the risk of regression is high. Also not enough people reviewed it. > Jie Song <[email protected]> writes: > > > From: Jie Song <[email protected]> > > > > When starting a dummy QEMU process with virsh version, monitor_init_qmp() > > enables IOThread monitoring of the QMP fd by default. However, a race > > condition exists during the initialization phase: the IOThread only removes > > the main thread's fd watch when it reaches > > qio_net_listener_set_client_func_full(), > > which may be delayed under high system load. > > > > This creates a window between monitor_qmp_setup_handlers_bh() and > > qio_net_listener_set_client_func_full() where both the main thread and > > IOThread are simultaneously monitoring the same fd and processing events. > > This race can cause either the main thread or the IOThread to hang and > > become unresponsive. > > > > Fix this by proactively cleaning up the listener's IO sources in > > monitor_init_qmp() before the IOThread initializes QMP monitoring, > > ensuring exclusive fd ownership and eliminating the race condition. > > > > Signed-off-by: Jie Song <[email protected]> > > Reviewed-by: Marc-André Lureau <[email protected]> > -- Marc-André Lureau
