On Fr, 2016-11-11 at 17:28 +0100, Jiri Slaby wrote: > On 11/09/2016, 09:01 AM, Gerd Hoffmann wrote: > > On Di, 2016-11-08 at 22:37 +0200, Michael S. Tsirkin wrote: > >> On Mon, Nov 07, 2016 at 09:43:24AM +0100, Jiri Slaby wrote: > >>> Hi, > >>> > >>> I can relatively easily reproduce this bug: > > > > How? > > Run dmesg -w in the qemu window (virtio_gpu) to see a lot of output.
fbcon? Or xorg/wayland with terminal app? > Run pps [1] without exit(0); on e.g. serial console. > Wait a bit. The lot of output causes the BUG. > > [1] https://github.com/jirislaby/collected_sources/blob/master/pps.c > > >>> BUG: 'list_empty(&vgdev->free_vbufs)' is true! > > > >> The following might be helpful for debugging - if kernel still will > >> not stop panicing, we are looking at some kind > >> of memory corruption. > > > > Looking carefully through the code I think it isn't impossible to > > trigger this, but you need for that: > > > > (1) command queue full (quite possible), > > (2) cursor queue full too (unlikely), and > > (3) multiple threads trying to submit commands and waiting for free > > space in the command queue (possible with virgl enabled). > > I use -vga virtio with no -display option, so no virtgl, I suppose: > [drm] virgl 3d acceleration not available > > > Do things improve if you allocate some extra bufs? > > > > int virtio_gpu_alloc_vbufs(struct virtio_gpu_device *vgdev) > > { > > struct virtio_gpu_vbuffer *vbuf; > > - int i, size, count = 0; > > + int i, size, count = 16; > > This seems to help. > > thanks,
