ping ping! On 24.01.2019 10:48, Denis Plotnikov wrote: > When there is a Backup Block Job running and shutdown command is sent to > a guest, the guest crushes due to assert(!bs->walking_aio_notifiers). > > Call stack: > > 0 __GI_raise > 1 __GI_abort > 2 __assert_fail_base > 3 __GI___assert_fail > 4 bdrv_detach_aio_context (bs=0x55f54d65c000) <<< > 5 bdrv_detach_aio_context (bs=0x55f54fc8a800) > 6 bdrv_set_aio_context (bs=0x55f54fc8a800, ...) > 7 block_job_attached_aio_context > 8 bdrv_attach_aio_context (bs=0x55f54d65c000, ...) <<< > 9 bdrv_set_aio_context (bs=0x55f54d65c000) > 10 blk_set_aio_context > 11 virtio_blk_data_plane_stop > 12 virtio_bus_stop_ioeventfd > 13 virtio_vmstate_change > 14 vm_state_notify (running=0, state=RUN_STATE_SHUTDOWN) > 15 do_vm_stop (state=RUN_STATE_SHUTDOWN, send_stop=true) > 16 vm_stop (state=RUN_STATE_SHUTDOWN) > 17 main_loop_should_exit > 18 main_loop > 19 main > > This happens because of "new" context attachment to VM disk bds. > When attaching a new context the corresponding aio context handler is > called for each of aio_notifiers registered on the VM disk bds context. > Among those handlers there is the block_job_attached_aio_context handler > which sets a new aio context for the block job bds. When doing so, > the old context is detached from all the block job bds children and one of > them is the VM disk bds, serving as backing store for the blockjob bds, > although the VM disk bds is actually the initializer of that process. > Since the VM disk bds is protected with walking_aio_notifiers flag > from double processing in recursive calls, the assert fires. > > The patch fixes the problem by skipping the bds-es in recursive calls > which have started attachment/detachment already. > > Signed-off-by: Denis Plotnikov <dplotni...@virtuozzo.com> > --- > block.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/block.c b/block.c > index 9b1c5c5eaf..35a19fe1df 100644 > --- a/block.c > +++ b/block.c > @@ -5064,7 +5064,9 @@ void bdrv_detach_aio_context(BlockDriverState *bs) > bs->drv->bdrv_detach_aio_context(bs); > } > QLIST_FOREACH(child, &bs->children, next) { > - bdrv_detach_aio_context(child->bs); > + if (!child->bs->walking_aio_notifiers) { > + bdrv_detach_aio_context(child->bs); > + } > } > > bs->aio_context = NULL; > @@ -5083,7 +5085,9 @@ void bdrv_attach_aio_context(BlockDriverState *bs, > bs->aio_context = new_context; > > QLIST_FOREACH(child, &bs->children, next) { > - bdrv_attach_aio_context(child->bs, new_context); > + if (!child->bs->walking_aio_notifiers) { > + bdrv_attach_aio_context(child->bs, new_context); > + } > } > if (bs->drv->bdrv_attach_aio_context) { > bs->drv->bdrv_attach_aio_context(bs, new_context); >
-- Best, Denis