Hi, I'm using qemu 4.0 and hit segfault when tearing down kata sandbox, I think it's because io completion hits use-after-free when device is already gone. Is this a known bug that has been fixed? (I went through the git log but didn't find anything obvious).
gdb backtrace is: Core was generated by `/usr/local/libexec/qemu-kvm -name sandbox-5b8df8c6c6901c3c0a9b02879be10fe8d69d6'. Program terminated with signal 11, Segmentation fault. #0 object_get_class (obj=obj@entry=0x0) at /usr/src/debug/qemu-4.0/qom/object.c:903 903 return obj->class; (gdb) bt #0 object_get_class (obj=obj@entry=0x0) at /usr/src/debug/qemu-4.0/qom/object.c:903 #1 0x0000558a2c009e9b in virtio_notify_vector (vdev=0x558a2e7751d0, vector=<optimized out>) at /usr/src/debug/qemu-4.0/hw/virtio/virtio.c:1118 #2 0x0000558a2bfdcb1e in virtio_blk_discard_write_zeroes_complete ( opaque=0x558a2f2fd420, ret=0) at /usr/src/debug/qemu-4.0/hw/block/virtio-blk.c:186 #3 0x0000558a2c261c7e in blk_aio_complete (acb=0x558a2eed7420) at /usr/src/debug/qemu-4.0/block/block-backend.c:1305 #4 0x0000558a2c3031db in coroutine_trampoline (i0=<optimized out>, i1=<optimized out>) at /usr/src/debug/qemu-4.0/util/coroutine-ucontext.c:116 #5 0x00007f45b2f8b080 in ?? () from /lib64/libc.so.6 #6 0x00007fff9ed75780 in ?? () #7 0x0000000000000000 in ?? () It seems like qemu was completing a discard/write_zero request, but parent BusState was already freed & set to NULL. Do we need to drain all pending request before unrealizing virtio-blk device? Like the following patch proposed? https://lists.gnu.org/archive/html/qemu-devel/2017-06/msg02945.html If more info is needed, please let me know. Thanks, Eryu
